May 17, 2014
Posted by Karachi Board Notes
Homeostatis
2nd Year Biology Notes
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Homeostatis
Definition
Home means same and statis means state. So the regulatory mechanism
which maintained the internal environment of a organism is called
homeostatis.
Important Aspects of Homeostatis
There are three important aspects of homeostatis.
- Osmoregulation
- Thermoregulation
- Excretion
Feed Back System
The check and balance system in a body is called feed back system. In a feed back system three organs are involved.
1. Receptor
The organ which receive any change in the internal environment of the body are called Receptor.
2. Effector
The central nervous system which send the message to a particular organ are called effector. Take part in particular action.
3. Central Nervous System
The receptor transfer message to a central nervous system such as brain.
Types of Feed Back System
There are two type of feed back system.
- Positive Feed Back System
- Negative Feed Back System
1. Positive Feed Back System
When there is a change in the internal environment and it is further
increase by the process are called positive feed back system.
2. Negative Feed Back System
When there is a change in the internal environment and it is further
decreased by the process called negative feed back system.
Osmoregulation
Definition
The regulatory mechanism which maintain the balance between water and solute context of a cell is called osmoregulation.
Osmoregulation in Plant
Due to the availability of water there are four groups of plant.
- Hydrophyte
- Halophyte
- Xerophyte
- Mesophyte
Hydrophyte
The group of plant which is grow in fresh water are called hydrophyte.
Characteristic of Hydrophyte
- The plant do not have layer of cuticle.
- The leave have stomata in the upper surface with take part in transpiration.
- The root are either absent or poorly developed.
Example
Hydrilla, Lotus, Lily plant
Halophytes
The group of plant which is grow in marshy soil or salty soil are called halophyte.
Characteristic of Halophyte
- These plant absorb water from such a soil, which is higher salt concentration and low water potential.
- Halophyte actively absorption salt into their roots.
- In the leaves of plants salt glands are present which helps in the removal of salt and water from the body.
- Some halophytes absorb humidity by leave.
Example
Glass wort, Cord grass
Mesophyte
The group of plant which is grow in well watered soil are called mesophyte.
Characteristics of Mesophyte
- Their roots are well developed.
- Their body is covered by a layer called cuticle.
- They contain stomata for evaporation of extra water.
- Some mesophyte excrete out water in the form of drop this process is called guttation.
Xerophyte
The group of plant which is grow in dry places such as desert are called Xerophyte.
Characteristic of Xerophyte
- Some plants do not face dry consition and produce seed are called ephemeral plant. During raining season seeds germinate.
- Their root are well develop which go deep into the soil to absorb water.
- Some plant have horizontal root on the surface to absorb rain water rapidly.
- Some plant leaves are modified into spine to prevent transpiration.
- Stem and leave covered by cuticle.
- Some plant store water in cell (succulent)
Example
Cacuts, Euphorbia.
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Excretion
Definition
The removal of harmful substance produce in the metabolic process from the body is called Excretion.
Excretion in Plant
In plant rate of catabolic process is very slow and waste product are
produce in less amount. They are used again in their anabolic process.
Waste Substance of Plant
The substance which are produce in excess amount are
- Water
- CO2 and O2
- Ions
Removal of Water
Extra water is removed from the body of plant by two methods.
Transpiration
The extra amount of water removed in the form of vapor through stomata is called transpiration.
Guttation
When water is removed from plant in the form of drop this process is
called Guttation. Guttation occur special opening called hydathods.
Guttation take place in those plant which grow in tropical rain forest.
Release of Oxygen and Carbondioxide
- In day time plant used CO2 for photosynthesis process and released O2.
- In night time plant released CO2 and inhale O2 gas.
Ions
Excess amount of ion are deposit into dead cell of plant body such as bark.
Thermoregulation
The maintained the temperature of the body with in a range is called thermoregulation.
Thermoregulation in Plant
The normal range of temperature in plant is 10oC to 35oC. The adaption of plant to low and high temperature are as follows.
Low Temperature
- At low temperature the nature of plasma membrane is changed
and produce crystalline structure due to which transport of solute is
slow.
- To control this condition plant cell produce unsaturated.
- At freezing point ice crystal are formed in the cell. But
the plant of cold region change the composition of solute of cell so
ice crystal are not formed in cytoplasm they form in cell wall. This
condition is known as freezing tolerance.
High Temperature
High temperature has more harmful than low temperature for plant.
- Due to high temperature all enzyme are denature and metabolic
process stop. So plant increase rate of transpiration and cool the
body.
- At above 40oC plant produce heat shock protein. They protect the enzyme from destroying.
- In some plant shiny cuticle is present which protest them from high temperature.
- In some plant leaves are reduce in size.
Osmoregulation In Animal
Osmoregulation in Terrestial Animal
In land animals excretion of water take place through body surface so
they have develop number of strategies to maintain Osmoregulation.
Water Proof External Covering Epidemics present in reptile, mammal cuticle present in insect which prevent the water loss from their body.
Storage and Excretion of Solid Wastes In birds, reptile
and insect store nitrogenous waste uric acid. Uric acid insoluble in
water and help to reabsorption of water in cloeca. Uric acid excreted
the body in the form of paste and crystal.
Use of Metabolic Water
Some mammal fat is converted into simple compound and during this
process water is produce which is reused in the body. Camel, Kangroo
used metabolic water.
Storage of Harmful Waste In mammal urea in kidney which is helps in reabsorption of water.
Osmoregulation in Aquatic Animal
Osmoregulation in fresh water animal is maintained by two methods.
1. By Contractile Vacuole
2. By producing dilute urine
1. By Contractile Vacuole
Fresh water unicellular organism have contractile vacuoles. Water with
dissolved CO2 and uric acid is collected from the endoplasm into the
contractile vacuole, which increase in size up to a maximum and burst
released the extra substance in environment. In Amoeba and Paramicium
the amount of water and other substance remain in balanced by
contractile vacuole.
2. By Producing Dilute Urine
Fresh water fishes have hypertonic body fluid as compare to surrounding
water. Fisher released extra amount of water in the form of dilute
urine and absorb some essential ion from outside to maintain the salt
and water content in the body.
Osmoregulation in Marine Animal
Marine water fishes have hypotonic body fluid than surrounding because
sea water have high concentration of salt so these fishes drink water
continuously and the salt excreted out along with concentrated urine.
They also excrete salt through gills.
Excretion in Animal
In animal removal of nitrogenous waste from the body is very
essential. Animal have particular organ to excrete out nitrogenous
waste.
Waste Substance of Animal
Animal produce different type of waste substance such as
1. Ammonia
2. Urea
3. Uric Acid
4. Creatinine
5. Hypozenthine
1. Ammonia
- It is a small molecule of gas. Its formula is NH3.
- It is highly soluble in water.
- It is very toxic compound
- It is dissolved in water and removes by simple diffusion method through skin or by urine.
- It is excretory substance of aquatic animal e.g. fishes.
2. Urea
- Urea is less soluble in water.
- Its formula is CO(NH2).
- Urea is very less toxic substance because its 1,00,000 time less toxic then NH3.
- Urea is produce as a result of metabolism in the liver from ammonia.
NH3 + CO2 ------> Citruline ------> Aginine ------> Urea
- This process required energy.
- Urea is the excretory product of mostly land animal like mammals.
3. Uric Acid
- Its formula is C5O3N4H4.
- It is not soluble in water.
- Uric Acid is less toxic than urea.
- Uric Acid released from the body in paste like substance or urete crystal.
- Urid Acid is the excretory product of insect, birds and reptile.
Excretion in Hydra
(Exetory Substance (NH3))
Hydra is a water living animal. In this body the excretory products are
produced in the form of NH3. It is excreted out the gastrovascular
cavity and then removed from the body along with water.
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Excretion in Planaria
(Exetory Organs)
In planaria nitrogenous waste excrete out through skin and special excretory organ called flame call or protonephridia.
Structure of Excretory System and Functions
In the body of planaria there is a system of branch tube like bodies.
There are two longitudinal excretory trunks one on either side of the
body.
Nephredipores
They open to the out side by small pore called nephredipores.
Flame Cell
Internally these excretory trunk divide and redivide into number of
small branches at the end of the branch special cell are present are
called flame cell. The flame cells are club-shaped hollow cells. In
their internal cavity many cilia are attached which perform movement
just like flame of candle.
Functions
All the waste product of main branches absorb by flame cell because
the movement of cilia of flame cell. When the excretory product come
into the longitudinal excretory system they are removed out of the body
through the nephrediopore.
Excretory Organs
The excretory system of earthworm consist of small, coiled tubes called Metanephredia. It is present in each segment.
Structure of Nephredium
Each Nephredium consist of three part.
1. Nephrostome
It is a rounded, ciliated funnel with the opening.
2. Bladder
Main body of nephridum consist of coiled tubular part and wide part called bladder.
3. Nephridiopore
The bladder opens outside by a small pore on the skin are called nephridiopore.
Excretion
As fluid moves along the tubule, epithelium reabsorbs the salt from
lumen and send to blood vessels surrounding the nephridium. The left
over appears as urine containing nitrogenous waste.
Excretion in Cockroach
Excretory Organs
Cockroach have special tube like excretory structure are called
"Malphighian Tubules". It is present between the mid gut and hind gut.
It is embedded in the blood.
Excretion
Malphighian tubules absorb all nitrogenous waste from blood and pour
them into illium. The latter part of tubules reabsorbs important
substance. The uric acid when come into rectum, it also reabsorbs water
and salt, so uric became almost dry then it is excreted out of the
body.
Liver
Liver is the large raddish brown glandular organ which is central
station of metabolism and consequently the body is central metabolism
clearing house.
Location
Liver located in the abdomen just below the diaphragm.
Functions of Liver
Liver is the main homeostatis organ which perform several function.
1. Metabolism of CHO and LIPIDS
- Liver is the center of metabolism. Is take part in metabolism
of carbohydrate and lipid. It regulates the amount of glucose into the
blood. Excess glucose is converted into glycogen, which is reserve
food. It amount of glucose is decrease in the blood glycogen is broken
into glucose. Glycogen is reduce than liver convert amino acid into
glucose.
- Liver also help in oxidation of lipid. It is converted blood lipid into simple fat which is stored in the body.
2. Deamination and Urea Formation
Excess of protein can not be store in body. Protein are change into
amino acid. Amine group is removed from the amino acid this process is
called deamination of form NH3. Amonia combine with CO2 and convert
into urea by a cycle called ornithine cycle.
3. Production of Bile
Liver produce a secretion called Bile. It is yellowish green alkaline
substance. Bile contain bile pigment biliverdin, bilirubin, salt such
as sodium-glycocholate, Na-taurocholate, Cholesterol, Phospholipid and
mucous.
Functions of Bile
- Bile neutralizes the acidic food
- It kills the germs
- It takes part in the emulsification of fat.
4. Detoxification
Liver convert toxic substance into non toxic substance this process are called detoxification.
For example a compound hydrogen peroxide H2O2 is a
harmful compound. The liver secrete on enzyme catalase which convert
H2O2 into H2 and O2 and became non poisonous substance.
5. Formation of Cholesterol
Liver also forms cholesterol which is necessary for the body. Its extra amount is always excreted along with water.
5. Formation of Cholesterol
Liver also forms cholesterol which is necessary for the body. Its extra amount is always excreted along with water.
6. Thermoregulation
Liver helps in regulation of body temperature by continue supply of blood and metabolic process.
7. Storage of Vitamins
Liver stores vitamins such as A1B and D.
and produce crystalline structure due to which transport of solute is
slow.
the plant of cold region change the composition of solute of cell so
ice crystal are not formed in cytoplasm they form in cell wall. This
condition is known as freezing tolerance.
process stop. So plant increase rate of transpiration and cool the
body.
of carbohydrate and lipid. It regulates the amount of glucose into the
blood. Excess glucose is converted into glycogen, which is reserve
food. It amount of glucose is decrease in the blood glycogen is broken
into glucose. Glycogen is reduce than liver convert amino acid into
glucose.
_________________________________________________________________________________
Urinary System in Human Being
Urinary system of man consist of
Kidney
Kidneys are pair of dark red bean shaped structures which are attached to the dorsal wall of the abdominal cavity.
- Kidney are covered by a membrane are called peritoneum.
Ureter
Urine leaves the kidney through a pair of duct called Ureter.
Bladder
The ureters of both kidney drain into pear shaped thin walled structure are called bladder.
Urethra
Urine leaves the body during urination from the bladder through a tube called Urethra.
Sphincter
Sphincter muscles near the junction of the urethra and bladder control the urine in bladder.
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Kidney
Kidney are a pair of dark red bean shaped structures which are attached to the dorsal wall of the abdominal cavity.
Structure of Kidney
Internally kidney consist of two part
1. Cortex is the outer and darker region.
2. Medulla is the inner and lighter region in the kidney. It contain many cone like structure are called pyramids.
Nephron
The basic structural and functional unit of kidney are called Nephron.
OR
Kidney consist of million of microtubules are called Nephron.
Structure of Nephron
Each nephron is sub-divided into
1. Renal Corpuscle
2. Renal Tubule
1. Renal Corpuscle
Each renal corpuscle is divides into two
i. Bowman's Capsule
ii. Glomerulus
i. Bowman's Capsule
In each nephron inner end forms a cup-shaped swelling called Bowman's capsule.
ii. Glomerulus
Each bowman's capsule have a ball of capillaries called glomerulus.
Glumerulus circulates blood through capsule as it arrives through
Aferent Arteriole. Blood carried away from the capsule by a small
vessel called Efferent Arteriole. The blood vessel sub divide again
into another network of capillaries called Peritubular Capillaries.
2. Renal Tubule
Bowman capsule continuous as extensively tubular system.
i. Proximal Convoluted tubule
ii. Loop of Henle
iii. Distal convoluted tubule
iv. Common collecting duct
i. Proximal Convoluted Tubule
Bowman capsule gives out a coiled tubule called Proximal Convoluted Tubule.
ii. Loop of Henle
The proximal convoluted opens into a U-Shaped structure called loop of
Henle. Loop of Henle consist of descending and ascending limbs.
iii. Distal Convoluted Tubule
The ascending limb of loop of Henle opens into another convoluted tubule called Distal Convoluted Tubule.
iv. Collecting Tubules
Distal tubule empties into collecting tubules which open into pelvis.
Functions of Kidney
Urine formation take place in these following steps:
1. Ultra Filtration
2. Selective Reabsorption
3. Tubular Secretion
4. Counter Current Exchange
2. Selective Reabsorption
All the important constituent of the glomerular filtrate are reabsorbed when filtrate pass in tubular system.
- Prominal convoluted tubule reabsorb salt amino acid, glucose and water.
- Descending limb of loop of Henle reabsorb Na and Cl inter
in the interstial fluid. Na and Cl reabsorbed by active transport.
Water is not reabsorb.
- Distal convoluted tubule have hypotonic solution due to
high concentration of water. In this part by the action of hormones
concentration of various salt is adjust.
3. Tubular Secretion
Tubular section is also very important process of excretion. The
tubular epithelium also secrete substances into teh lumen this secretion
is very selective and mainly of hydrogen into balance pH value of the
filtrate passing through the tubule.
4. Counter Current Exchange
The exchange of solute and water in the medulla of kidney is called counter current exchange. There are two counter exchanges:
i. Counter Current Multiplier
ii. Counter Current of Vasa Recta
i. Counter Current Multiplier
When the filtrate passes through the descending limb of loop of Henle
water is reabsorbe due to this process the filtrate became hypertonic.
ii. Counter Current of Vasa Recta
The blood vessels which run parallel to the loop of Henle are called
Vasa recta. Through these blood vessels only about 10% of blood of
kidney passes very slowly. This blood supplies oxygen and nourishment
to the cell of medulla and carries away the reabsorb water from the
filtrate. The system is regulate and maintained properly.
Reabsorption in the Nephron
Types of Nephron
There are two type of nephron
1. Cortical Nephron
2. Juxtamedullary Nephron
1. Cortical Nephron
The nephron which have small length of loop of Henle and only present in cortex region of kidney are called Cortical Nephron.
2. Juxtamedullary Nephron
These nephron have long loop medullar of kidney reabsorb more water are called juxtamedullary nephron.
Effect of Hormones on the Working of kidney
Certain hormones control the working of kidney.
1. Andiurelic Hormones (ADH)
2. Aldosteron Hormones (AH)
3. Parathormon Hormone (PTH)
1. Antidiurelic Hormones
Pituitary gland secrete ADH. It is also called vasopressin.
Functions
Hormones helps in reabsorption of water. Hormone is produce at the time
of dehydration. It causes shortage of water in the body due to rapid
loss of water. The osmotic pressure of blob increases. This hormone
helps to balance the amount of water.
2. Aldosteron Hormones
Outer part of adrenal cortex secreted aldosteron harmine.
Functions
It control the concentration of Na+ in the bosy fluid. It increase the reabsorption of sodium ion in nephrone.
3. Parathormon Hormones
Parathyroid gland secrete parathormone.
Kidney Problem
Kidney is not perform properly due to different reason are called Kidney problem or Kidney disease.
There are many problems of kidney
1. Kidney Stone
2. Renal Failure
1. Kidney Stone
Stone solid materials are found in the kidney called Kidney Stone.
Causes
Kidney stones are caused by metabolic disease.
70% of kidney stone are formed due to calcium oxalate and phosphate
oxalate. Oxalate are produced in the metabolic process and added in the
urine and deposit in kidney change into stones. Oxalates are present
in green vegetables and tomatoes therefore may be the source of oxalate
stone.
Infective Stone
20% stone are called as infective stone. Infective stone consist of combination of calcium, magnesium and ammonium phosphate.
Uric Acid Stone
5% stone are formed in uric acid.
Cure
Lithotripsy
The lithotripsy is used for non surgical removal of kidney stone. It is
a technique used to break up stones that form in the kidney, ureter or
gall bladder.
Method
There are several way to do it although the most common is shock wave
lithotripsy or ultrasonic lithotripsy. High concentration X-Ray or
ultrasound are directed from a machine outside the body to the stone
inside. The shock waves break the stone in tiny pieces or into sand
which are passed out of the body in urine.
Renal Failure
Sometimes the working of kidney is badly damaged due to certain
reason or infection. They are not able to filter the harmful
nitrogenous substance it is called renal failure. In such condition the
harmful substance remain in blood.
Symptoms
- Nausea
- Vomiting
- Loss of appetite
- Weakness
- Difficulty in breathing
In severe condition patient may suffer by pneumonia high blood pressure coma and ultimately death.
Treatment of Kidney Failure
Dialysis
A technique to remove nitrogenous wastes particularly the urea from the blood of the patient is called Dialysis.
Type of Dialysis
There are two types of dialysis
1. Haemodialysis
2. Peritoneal Dialysis
1. Haemodialysis
Haemodialysis means "Cleaning the blood". In this procedure blood is
circulated through a machine which contains a dialyzer also called on
artificial kidney.
Dialyzer has two spaces separated by thin membrance and dialysis fluid
on the other. The waste and excess water pass from the blood through
the membrane into the dialysis fluid. Dialysis take place 6 to 10 hours
and 3 time in a week.
2. Peritoneal Dialysis
Abdomen has a peritoneal, lined by a thin epithelium called peritoneum.
Peritoneal cavity is filled with dialysis fluid that enters the body
through a catheter. Excess water and wastes pass through the peritoneum
into the dialysis fluid. This process is repeated several times in a
day.
Kidney Transplant
Dialysis may be used as temporary measure. In high degree renal failure
also called as Uremia or end stage renal disease, the dialysis is done
endlessly thus the surgical transplantation of matching donor kidney
is only the option left as the permanent treatment.
Thermoregulation in Animal
Temperature Classification of Animal
According to the body temperature animals are divides into two group.
1. Poikilotherms (Cold Blooded)
2. Homeotherms (Warm Blooded)
1. Poikilotherms
Animal cannot maintain their body temperature and it can be changed accordingto the climate are called Poikilotherms.
Example
Amphibians, Reptile, Fishes.
2. Homeotherms
Animal can maintain their body temperature. It does not changed according to their environment are called Homeotherm.
Example
Birds, Mammals
Many poikilotherm can maintain their body temperature and homeotherm do
not maintain their body temperature always. So there terms are
changed.
Modern Classification of Animal
The modern classification of animal according to the body temperature.
1. Ectothermic
2. Endothermic
3. Heterothermic
1. Ectothermic
Ecto mean outside thermic mean heat so those animal obtained heat energy from their environment are called Ecotothermic.
Example
Invertibrate, Fish, Amphibian and Reptile.
2. Endothermic
Endo mean inside thermic mean heat so those animals use internal energy which is produced during their metabolism.
Example
Mammalia, Birds and Some Fishes.
3. Heterothermic
Those animals are able to maintain their body temperature with
certain variation, so their body temperature can be changed upto
certain limits are called Heterothermic.
Example
Bat, Humming birds.
Method of Thermoregulation in Animals
In animal thermoregulation occurs by two ways.
1. Behavioral Regulation
2. Physiological Regulation
1. Behavioral Regulation
When temperature is maintained by the activity of animal body, it is
called behavior regulation, such as animals change their position to
increase or decrease the temperature.
2. Physiological Regulation
When temperature of the body is maintained by inter-physiological
process it is called physiological regulation, such as change in blood
circulation etc.
Thermoregulation in Cold Temperature
In cold temperature animal regulate their body temperature by two methods.
1. Physiological Process
2. Behavioral Process
1. Physiological Regulation
This is the internal process of the body to maintain body temperature. It take place by two way
i. Non-shivering thermogenesis
ii. Shivering thermogenesis
i. Non-Shivering Thermogenesis
Hormones trigger the heat production as do thyroid hormones are called Non-shivering thermogenesis.
Mechanism
In this mechanism heat is produce by three methods.
- Erection of hairs
- Reduction of blood flow toward skin
- Sub cutaneous fat accumulation
Erection of Hairs
In cold season the hair become in erect position. In furry animals air
is trapped between the space of hairs and loss of body heat is stopped.
Reduction in Blood Flow toward Skin
In cold season the blood vessels of skin are reduced. It is called
Vasoconstriction. Due to this process blood flow towards skin become
slow and loss of heat through skin is reduced.
Sub Cutaneous Fat Accumulation
In mammals below skin fat is deposited in adipose cell. It prevent the
loss of body heat. It is common in aquatic animals such as Seal, Whale.
ii. Shivering Thermogenesis
The rate of heat production is increased y increased muscle
contraction by movement or shivering so called as shivering
thermogenesis.
Mechanism
In very cold weather shivering occur in the muscles of the body. It
produce heat Rate of Metabolism become faster. In this mechanism
hormones are involved one hormone adrenaline is produce by adrenal
gland. It increases the supply of glucose in blood so respiration become
fast and energy is produce.
Thyroid gland also secreted thyroxin hormone in blood. This hormone also increased respiration to produce heat.
2. Behavioral Process
In this mechanism the animals produce heat by their body activities.
Movement toward Hot Place
Animals move toward hot places during cold season.
Gathering of Animals
The animals come close to each other, so energy is produced.
Use of Warm Cloths
Man used warm clothes for protection and to get heat.
Thermoregulation in Hot Temperature
In hot season the animal produce less heat and also released heat from their body. It take place by two method.
1. Physiological Mechanism
2. Behavioral Mechanism
1. Physiological Mechanism
This process take place by following method.
Less Fats Deposition
In hot season fat is not deposit in below the skin. It loss the body heat.
Increase in Blood Flow toward Skin
In hot season the blood vessels of skin are dilated and vasodialation occur to released body heat.
Softness of Hair
Hair of skin not erect in hot season not prevent the loss of heat energy.
Sweet Gland
Sweet glands become active and water is excreted out through skin. The
blood becomes cold and internal temperature is maintained. It is called
physiological temperature regulation.
2. Behavioral Mechanism
In this mechanism the animal released heat by their body activities.
Movement toward Cold Places
Animal move from hot to cold places. They remain in shade or moist place to reduce their body heat.
Use of Thin Clothes
Man use thin clothes during summer season.
Role of Brain in Thermoregulation
The body temperature regulation in human is based on complex homeostatic system facilitated by feedback mechanism.
The Control Center
The homeostatic thermostate is present in the hypothalamus, a brain
part. It respond to the changes in the temperature above and below
37oC.
Warm Temperature
Incase of increase in temperature above 37oC certain warm temperature
sensitive thermoreceptors in skin, hypothalamus and other parts of
nervous system send the signals to the system that increase the blood
flow to the skin and also cause sweat gland activation and sweat is
evaporated for the cooling.
Cold Temperature
In cold temperature, the cold receptor send the impulse to hypothalamus
to inhibit heat loss mechanism and activate the heat conservation
mechanism.
Fever
When the temperature of the body is increased beyond a set point it is called Fever or Pyrexia.
Cause of Fever
The main cause of fever is the viral or bacterial infection. These
germs in blood vessels produce a chemical substance called pyrogen. It
increases the body temperature than normal.
Importance
- Fever helps to kill the germs
- It indicates any abnormal condition in the body or infection.
Homeostatis 2nd Year Biology Notes http://karachiboardnotes.blogspot.com/ Homeostatis Definition Home means same and statis means state....
May 17, 2014
Posted by Karachi Board Notes
Botany MCQs
2nd Year Biology Notes
Botany MCQs Karachi Board BISE Karachi Notes
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1. When the plasmolysed cells are again placed in water, there is a
recovery to the original condition due to endosmosis of water. This is
called __________.
(Plasmolysis, Incipient Plasmolysis, Complete Plasmolysis, Deplasmolysis)
2. Rizobium is found in __________.
(Roots of wheat, Roots of rice, Root-nodules of pea, Deplasmolysis)
3. The oxygen released in photosynthesis comes from __________.
(Carbon dioxide, Carbohydrates, Water, None of above)
4. Cell organella related with respiration is __________.
(Mitochondria, Centriole, Coldgi Body, Nucleus)
5. The end products of glycolysis is __________.
(Citric Acid, Pyruvic Acid, Ethyl alcohol, Glyceraldehyde)
6. Positive geotropism is observed in __________.
(Primary roots, Sucking roots, Aerial roots, None of these)
7. Absorption of water by roots is increased when __________.
(Transpiration rate is less, Salt absorption is increased, Transpiratin rate is incrreased. Photosynthesis rate is increased)
8. In plant cell vacuole contains __________.
(Gases, Vacuum, Dissolved Mineral salts, Water)
9. The union of male and female gametes results in the formation of __________.
(Aplanospore, Meiospore, Zygote, None of these)
10. Enzymes are basically __________.
(Proteins, Vitamins, Fats, Carbohydrates)
11. Semi-permeability is the property of __________.
(Plasma Membrane, Cell wall, Colgi body, Endoplasmic Reticulum)
12. The initial stage of water absorption by root cell is by __________.
(Osmosis, Imbibition, Absorption, Diffusion)
13. Duplication of DNA is called __________.
(Transduction, Transcription, Translation, Replication)
14. Watson and Crick are credited for finding __________.
(DNA is the carrier of genetic information, DNA is a double-stranded
helix, RNA is a double-stranded helix, DNA is composed of sugar,
phosphoric acid and nitrogenous bases)
15. __________ is the unit of inheritance.
(Phenotype, Genotype, Gene, None of these)
16. __________ organalle is related with genetic engineering.
(Plastids, Plasmids, Mutations, Hybrid Vigour)
17. The pollen tube which moves through the style towards ovary is an example of __________.
(Phototropism, Thigmotropism, Hydrotropism, None of these)
18. Cytokinins promote __________.
(Cell division, Apical growth, Tallness, Dwarfness)
19. The number of chromosomes in humans is __________.
(56, 46, 36)
20. The tendency of genes to remain together is called __________.
(Linkage, Crossing over, Gena mutation)
21. Cross fertilization of phenotypically dominant individual with a homozygous recessive individual is __________.
(Dihybrid cross, Munohybrid Cross, Test Cross)
22. Cytokinesis is the division of __________.
(Nucleus, Cytoplasm, Vacuole)
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23. Inheritance of acquired characters was suggested by __________.
(Wallace, Aristotle, Lamarck)
24. Translocation of organic food substances takes place through __________.
(Xylem, Phloem, Endodermis)
25. Absorption of water and mineral salts from the soil takes place through __________.
(Older roots, Younger roots, Both of them)
26. Respiration in plants takes place during __________.
(Day time only, Night time only, Day and night both)
27. Process of transpiration is effected by __________.
(Light only, temperature only, both of these)
28. Mitosis takes place in __________.
(Somatic Cell, Sickle cell, Zylem Cell)
29. Transpiration is necessary for __________.
(Movement of Curvature, Synthesis of food material, Conduction of Water)
30. Munch Hypothesis was proposed to explain __________.
(Translocation, Ascent of Sap, Transpiration)
31. Human male set of chromosomes is __________.
(44 + xy, 44 + xx, 44 + 00)
32. The first stable compound formed during photosynthesis is __________.
(ATP, 3PGA, Pyruvic Acid)
33. During Meiosis crossing over takes place at __________.
(Leptotene, Diplotene, Diakenesis)
34. Paleontology evidences are considered as evidence of __________.
(Vestiges, Fossils, Embryo)
35. The genotype of Hybrid is __________.
(T, Tt, tt)
36. The blood group of a man with neither antigens is __________.
(‘O’ Group, ‘A’ Group, ‘AB’ Group)
37. The changes in chromosomes are called __________.
(Linkage, Crossing over, Chromosomal aberration)
38. The growth in plants can be measured by __________.
(Photometer, Respirometer, Auxanometer)
39. Oxygen is evolved during photosynthesis from __________.
(Water, Carbon dioxide, Carbohydrate)
40. The two chromatics of each chromosome are held together at __________.
(Centromere, Centrosome, Chiasma)
41. The sex-linked character in man is __________.
(Hieght, Colour-blindness, Colour of skin)
42. A bacterial cell divides by __________.
(Mitosis, Amitosis, Meiosis)
43. Gene pool is the sum total of __________.
(Genes, Gene frequency, Gene in population)
44. Karyokinesis is the division of __________.
(Nucleus, Cytoplasm, Vacuole)
45. The cell wall is __________.
(Permeable, Impermeable, Semipermeable)
46. The opening and closing of stomata are controlled by __________.
(Stomatal cells, Guard cells, Zylem Cells)
47. The physical process in which water is sucked up by a certain dry or semi-dry material is __________.
(Diffusion, Imbibition, Osmosis, Plasmolysis)
48. Inheritance and variation in living things is explained by __________.
(Ecology, Genetics, Taxonomy, Anatomy)
49. The relative time of day and night to which plant is exposed is __________.
(Photophosphorylation, Phototaxis, Photoperiodism, Phototropism)
50. In meiosis, the snapsis of homologous chromosomes takes place at this sub stage __________.
(Pachytene, Zygotene, Leptotene, Diplotene)
51. The human blood genetic disease in which the red blood cells become of abnormal shape is called __________.
(Anemia, Pneumonia, Insomnia, Sickle-cell anemia)
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Botany True and False 2010
2nd Year Biology Notes
Botany True and False 2010
http://karachiboardnotes.blogspot.com/
1. There are three phases of growth namely Cell division, Cell enlargement and Cell differentiation.
2. The influence of the duration of daily periods of light and darkness on the flowering is known as phototropism.
3. Mimosa pudica shows tropic movements.
4. The water rises up in the plants through xylem vessel.
5. Monosomic is a condition when there is one chromosome less than the original number (2n-1).
6. Sex-linked character in man is Night blindness.
7. A bacterial cell divides by mitosis.
8. Anthocyanin pigment is present in chloroplast.
9. Nature has provided the cell with a means of temporary energy storage in the from of ATP.
10. Protein synthesis takes place in Ribosomes.
11. Anaerobic respiration takes place in the presence of oxygen.
12. Haemophilia is a genetic disease.
13. Gametes are always haploid.
14. Zygotes are always diploid.
15. A man having blood group “0” has two antigens.
16. Haemophilia is sex-linked disease.
17. Shrinkage of protoplasm due to loss of water from the vacuole is called Plasmolysis.
18. The raw materials used during photosynthesis are water and carbon dioxide.
19. Respiration is an anabolic process.
20. In higher plants growth takes place throughout the body.
21. Colour blindness is found more in women than in men.
22. Polyploidy is blood disease.
23. Turner’s syndrome is found in females only.
24. Meiosis takes place at the root and stem apexes of the plant.
25. Transpiration takes place from woody stem also.
26. Opening and closing of the stomata depends upon the turgidity of the guard cells.
27. Molecules of solute can pass though a permeable membrane.
28. The shrinkage of protoplasm takes place during the process of osmosis.
29. D.N.A is a genetic material.
30. Hemophilia is comparatively rare in women.
31. The cross between two individuals differencing in two traits is called Dihybrid cross.
32. Down Syndrome is a disease called Mongolism.
33. The nature of Dark Reaction was studied by Black man.
34. The contrasting characters or alternating forms of the same gene is called Allele.
35. Absorption of water from the soil takes place through xylem vessels.
36. During Meiosis the number of chromosomes remains constant.
37. Photolysis of water takes place during a light reaction.
38. Cuticle also takes part in transpiration.
39. Uracil base is present in D.N.A.
40. Respiration is a katabolic process.
41. Man is heterogametic
42. The drier the air, the more will be the rate of transpiration.
43. The gametes are always diploid.
44. Anthocyanin pigment is present in chloroplast.
45. Water moves in a plant even if there is no root pressure.
46. Transpiration mostly takes place through the roots.
47. Oxygen is evolved in photosynthesis by the splitting of molecules.
48. Nullisomic is a condition when there is one chromosome less than the original number.
49. Proteins are synthesized on the ribosomes.
50. The reversal in the sequence of genes within the chromosomes is called Inversion.
51. In moths, birds and some fishes the females are homogamatic and the males are heterogametic.
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Zoology Fill in the Blanks
2nd Year Biology Notes
http://karachiboardnotes.blogspot.com/
Zoology Fill in the Blanks
1. Salivary amylase digests carbohydrates in __________ medium.
2. The life-cycle of Plasmodium in mosquito discovered by __________.
3. The larva of Balanoglossus (acron worm( is called __________.
4. Legless amphibians are included in class __________.
5. Flame cells are found in __________.
6. Nephridia are the excretory organs of __________.
7. Butterfly exhibits __________ metamorphosis.
8. Euplectella belongs to __________.
9. Termites live in __________ colony.
10. Reptiles, birds and mammals are collectively called __________.
11. In sponges the spongocoel is lined with __________.
12. Cyclops is an example of the phylum __________.
13. In 1880 A.D Lavern discovered a protozoan parasite in the __________ of a malaria patient.
14. A protozoan parasite __________ causes human dysentery.
15. The organs of excretion in insects are __________.
16. There are five pairs of gills in __________ class of fish.
17. Saccutina a parasite of __________.
18. Thyroxine contains __________.
19. The larva of polychaete is called __________.
20. Elephantiasis is caused by __________.
21. The cnidoblasts are present in the phylum __________.
22. Rock mountain spotted fever is transmitted by cetain __________.
23. The end product of carbohydrate digestion is __________.
24. The contractile vacuole performs the function of __________.
25. Scyphistoma is the larval form of __________.
26. The study of the functions of the organs is known as __________.
27. Nearly 200 years ago the mammals evolved from __________
28. __________ is the largest gland.
29. Mantle is the characteristic of the phylum __________.
30. Class __________ has the largest number of species of the whole animal kingdom.
31. Kangaroo belongs to the sub class __________.
32. The locomotory organs of polychaets are __________.
33. Non-nucleated R.B.C are found in blood of __________.
34. The fore-brain consists of Telencephalon and __________.
35. Bat is a flying __________.
36. Phylum __________ and __________ include marine animals.
37. __________ is the unit of excretory organs.
38. Respiration is the process of __________.
39. __________ is an example of Polymorphism.
40. Book lungs are the respiratory organs of __________.
41. In insects the excretion is performed by __________.
42. Class Agnatha is also called __________.
43. Cortisone hormone is seceted by __________ gland.
44. Swim bladder is found in the class __________.
45. The larva of Neries is called __________.
46. Spider belongs to the class __________.
47. The heart of a bird is divided into __________ chambers.
48. Cercaria is the larva of __________.
49. The dendrons carry inpulse towards __________.
50. The outer layer of the wall of the eyeball is known as __________.
51. Flame cells are the organs of __________.
52. Balano glosus is included in the Phylum __________.
53. The meaning of malaria is __________.
54. The study of the internal structure of an organism is called __________.
55. Flame cells are excretory organs of phylum __________.
56. Trypanosome is a blood parasite.
57. The dissimilar teeth in mammals are called __________.
58. The respiratory organs of insects are __________.
59. The skeletal parts of sponges are called __________.
60. Nematocysts are found in the phylum __________.
61. Enzyme pepsin is secreted by the __________ glands.
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True and False - Zoology
2nd Year Biology Notes
True and False -
Zoology
Friendsmania.net
1. Bat is a flying bird.
2. Hydra is diploblastic animal.
3. Archaepteryx is a fossil bird.
4. Prototheria are egg-laying mammals.
5. Human heart is four-chambered.
6. Fishes respire through skin.
7. Intracellular digestion occurs between the cells.
8. Frog is a carnivorous animal.
9. Typhlosol is a dorsal absorptive ridge.
10. Water vascular system is present only in Echinodermata.
11. Melatonin is secreted by cretins.
12. The heart of the crocodile consists of three chambers.
13. The accumulation of nerves and sensory organs in the head is known as Caphalization.
14. The Prototherians are pouched mammals.
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15. Ammocoete is the larva of lamprey.
16. The spicules form the skeleton in sponges.
17. Plasmodium is an Endo-parasite.
18. Jelly-fish belongs to the class pieces.
19. Trypsin digests fats.
20. Pathology is the study of diseases.
21. Whale is a fish.
22. Planaria belongs to the phylum Oplatyhelminthes.
23. Neuron is the unit of the nervous system.
24. Throid gland secretes thyrotopins bormone.
25. Ascaris is found as a parasite in the intestine of man.
26. Amnion is the protective membrane of the embryo of frog.
27. Trypanosome is an external parasite.
28. Arteries carry the blood away from the heart.
29. Nephridia are respiratory organs.
30. Flagella are the organs of locomotion.
31. The inner ear is responsible for maintaing the balance of the body.
32. The cross section of the spinal cord shows the gray matter lying on the outside.
33. Pathology is the study of disease.
34. Gastrozooids are reproductive Zooids of the colony.
35. Amphioxus belongs to sub-phylum vertebrate.
36. Retina contains rods and cones.
37. Larynx is a part of the Digestive system.
38. Molluscus secrete shells of various types.
39. Mammals are Warm-blooded animals.
40. Intracellular digestion takes place between the cells.
41. Kiwi is a flying bird.
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Chapter 4 - Reproduction
2nd Year Biology Notes
Chapter 4 - Reproduction
Reproduction
The process through which organisms produce young ones of their own kind to maintain their species are called as Reproduction.
Types of Reproduction
There are two types of reproduction.
1. Asexual Reproduction
2. Sexual Reproduction
1. Asexual Reproduction
The type of reproduction in which fusion of gamets does not take place
and requires only a single parental organism and the offspring
produced are exact copies of their parents. This type of reproduction is
called Asexual Reproduction.
Asexual Reproduction of Plants
There are two methods of asexual reproduction in plants.
1. Natural Method of Asexual Reproduction
2. Artificial Method of Asexual Reproduction
1. Natural Method of Asexual Reproduction
In nature, plants reproduce asexually by following methods.
i. By Spores or Sporulation
ii. Vegetative Propagation
iii. Apomixis
i. By Spores or Sporulation
During alternation of generation plant produce haploid cell by meiosis
called Spores. Each spore can develop into new organism without
fertilization. The process of formation of unicellular spores is called
Sporulation.
Example
Sporulation occurs in bacteria, protozoans, algae, fungi, mosses and fern as well as plants.
ii. Vegetative Propagation
The process which involves the separation of the part of the parent
plant which then develop into new plant is called as Vegetative
Propagation.
OR
When a new plant develops from tissue, organs of a plant or outgrowth
of a plant. This type of reproduction is called Vegetative Propagation.
Process
In this process a plants part is separated which develops into new
plant such as stem, leaves roots or buds may take part in the formation
of new plant.
Methods of Vegetative Propagation
There are various method of propagation of plant by vegetative
reproduction for improving crops, orchads and ornamental plants are as
follows
i. By Cutting
ii. By Grafting
i. By Cutting
In this method stem or branch is cut from the plant. At the cut end of
the shoot a mass of dividing undifferentiated cells called a callus
forms and then adventitous roots develop form the callus. If the shoot
fragment includes a node, then adventitous root forms without callus
stage.
Example
Sugar cane, sweet potato and rose can be propagated by cutting. In
raspberry and black berries root cutting are also used for artificial
vegetative propagation.
ii. By Grafting
This is a technique whereby a branch from a desired variety of plant is
joined to another plant with well established root system. The plant
from which the branch is taken is called Scion and the plant to which
it is joined is called Stock. The two plants involved are normally the
different varieties of same species.
Example
Orange, lime and mango can be propagated by grafting.
iii. Apomixis
The modified form of asexual reproduction in which seeds are formed without fertilization is called Apomixis.
Mechanism
In apomixis, a diploid cell in the ovule gives rise to the embryo
without any fertilization and the ovules mature into the seeds.
Example
In Dandelions and other plants seed formation take place without fertilization.
2. Artificial Method of Asexual Reproduction
In plant vegetative reproduction is performed by artificial method, which are as follows
i. Tissue Culture or Test Tube Cloning
ii. Protoplast Fusion Technique
i. Tissue Culture or Test Tube Cloning
Tissue culture or cloning is a special technique which is used to
produce varieties of plants. By this technique, a group of genetically
identical offspring produced by asexual method called Clones.
Procedure
- In this method, pieces of tissues are cut from the parent
plant or from a single parenchymatous cell in a medium containing all
the nutrients and hormones.
- The culture cells divide and form an undifferentiated Callus.
- The callus then produces root and shoot with fully differentiated cells.
- The test tube plant can be transferred to soil where they continue their growth.
Application
In plants tissue culture is also used in genetic engineering. To
introduce new genes in plant body pieces of tissue or cells are used. By
this technique, we produced a new variety of plant by introducing new
DNA molecule.
Example
By cloning many thousand plants are produced from one plant. This method is used in Orchards and pinus trees to obtain wood.
Advantages of Tissue Culture
The main advantages of tissue culture are as follows
i. Development of Strong Plant: By this technique plants
of Agriculture and horticulture are produced. These plants are strong
than other plants produced by seeds.
ii. Development of Similar Plant: By this technique plants of similar character are developed.
iii. Development of Defence System in Plant: These plants have developed defence mechanism against any disease.
iv. Production of Useful Chemicals: By this technique,
many useful chemicals are obtained such as shikonin (a dye used in silk
and in the treatment of injuries caused by burning.
Disadvantages of Tissue Culture
There are also some disadvantages of tissue culture where are as follows
i. Production of Sterile Plant: The plant produced by this technique may be genetically sterile, do not reproduce by sexual method.
ii. Variation in Chromosome: This technique may cause change in the structure and number of chromosome.
ii. Protoplast Fusion Technique
Another technique known as protoplast fusion technique is developed to produce new varieties of plants.
Procedure
In this technique, outer cell wall is removed around the protoplast.
After protoplast of one or more cells are fused together, then their
protoplast are for culture. These protoplast produce a wall around
them, then they are change into new plant. Protoplast of either same or
different species may used for this technique.
Example
In potato and wild night shade plant this technique is used.
2. Sexual Reproduction
The type of reproduction in which fusion of gametes (sperm and ova)
take place and two parents (male and female) are involved is termed as
Sexual Reproduction.
Sexual Reproduction in Plant
In plants sexual reproduction takes place by three methods.
i. Isogamy
ii. Oogamy
iii. Heterogamy
i. Isogamy
The simplest type of sexual reproduction in which two morphologically
similar gametes take part in fertilization to produced zygospore which
then develop into new plant is called Isogamy.
It is also known as conjugation which means marriages of equals.
Example
This process occurs in algae and lower plants.
ii. Oogamy
The type of sexual reproduction in which a flagellated motile sperm
fertilizes with non motile egg to produced a diploid zygote which then
develop into new individual is called Oogamy.
Example
Some species of algae undergoes Oogamy.
iii. Heterogamy
The type of sexual reproduction in which two different structure gamets
fused i.e. non flagellated large size female gamete fuses with small
size flagellated male gamete to produced zygote which then develop into
new plant is called Heterogamy.
It is also known as anisogamy.
Example
In higher plants such as bryophyte, heterogamy is present.
Germination
The process in which dormant or sleeping embryo awakes up renews its life and develops into a seeding is called as Germination.
OR
The breaking of dormancy of seed to produce seedling is called Germination.
Kinds of Germination
Seed can germinate into three ways i.e.
1. Epigeal Germination
2. Hypogeal Germination
3. Viviparous Germination
1. Epigeal Germination
Epi => above, geo => earth
The kind of germination in which cotyledons came above the soil due to rapid growth of hypocotyl is called Epigeal Germination.
Example
Caster oil seed, tomato, cotton etc.
2. Hypogeal Germination
Hypo => below, geo => earth
The kind of germination in which cotyledons remain under the soil
due to rapid growth of epicotyl is called Hypogeal Germination.
Example
Maize-grain, Pea-gram etc.
3. Viviparous Germination
The special of germination in which seed germinates within fruit is called Viviparous Germination.
Process
The fruit is still attached to parent plant. Redicle comes out of the
fruit which becomes swollen and heavy due to increasing weight the
seedling gets detached and falls vertically into the soft mud gets
embeded and starts growing.
Example
Rhizophora, coconut, date palm etc.
Seed
Seed may be defined as
A ripened ovule or a part of a plant body in which embryo lives in dormant condition is called Seed.
Structure of Seed
Structure of seed can be divided into two parts
1. External Structure
2. Internal Structure
1. External Structure
Externally seed consists of following parts
Seed Coat
The seed is covered from outside by a coat called Seed Coat.
The seed coat is formed by integuments. It is made up of two layers.
Testa
The outer thicker layer is called Testa.
Tegmen
The inner thin layer is called Tegmen.
Chromosomes as Carrier of Genes
Genes are small bodies found in the chromosome.
Chromosome are considered as the carrier of genes.
- The chromosomes can be separately identified visually but the
genes are very small units. And so far have not been seen even with the
best microscope.
- The chromosome and gene behave as hereditary units but the genes can not be considered outside the chromosome.
- At the time of meiosis, the separation of homologous chromosomes takes place which result in the segregation of gene pairs.
- In the genotype of every individual one member of each
pair of genes is contributed by one parent and the other by the other
parent.
Chromosomal Theory of Heredity
Introduction
The chromosomal theory of inheritance was first formulated by the American Biologist "Walter Sutton" in 1902.
Postulates
The main postulates of this theory are as under
1. Hereditary Materials
Reproduction involves the initial union of only two cells, egg and
sperm. If Mendel's model is correct then these two gametes must make
equal hereditary contributions. Sperm, however contain little
cytoplasm, therefore the hereditary material must reside within the
nuclei of the gametes.
2. Segregation of Chromosomes
Chromosomes segregated during meiosis in a manner similar to that exhibited by the elements of Mendel's model.
3. Number of Chromosome
Gametes have one copy of each pair of homologous chromosomes, diploid individuals have two copies.
4. Independent Assortment
During meiosis each pair of homologous chromosomes orients on the metaphase plate independent of any other pair.
Objection
The objection on chromosomal theory of hereditary is that when there is
independent assortment of chromosomes in meiosis, the number of
factors (genes) is more than the number of chromosomes. This is
considered as a fatal objection about Sutton's theory.
Evidence
The material which transmits the parental characters into the coming generation is called Hereditary Material.
Fredrick Griffith's Experiment
Introduction
Fred Griffith in 1928 provided the evidence of hereditary material in bacteria.
Experimental Material
He was working on strains of steptococcus pneumoniae, which occurs in two distinct different forms.
R-Type
Rough surfaced, non-capsulated bacteria, without the capability of producing pneumonia.
i.e. non-virulent
S-Type
Smooth surfaced, capsulated bacteria, with the capability of producing pneumonia i.e. virulent.
Steps of Experiment
- He observed that when the injected R-type bacteria in the mice, there was no ill effect.
- When he injected the S-type, they proved to be fatal.
- He also observed, when he injected both the bacteria
separately after killing them by heating under high temperature, the
mice did not develop the disease.
- He also observed that, when the injected the living R-type with heat-killed S-type, there was a high morality among the mice.
Conclusion
Fred Griffith concluded that the R-type bacteria gained genetic
property of S-type inactive bacteria when they kept together, so R-type
bacteria converted into virulent S-type by the activity of DNA. Hence
by this experiment, it can be proved that DNA is a genetic material.
A Very, Macleod and McCarty's Experiment
Introduction
In 1944, after a decade of research, Oswald Avery, Maclyn McCarty and
Colin Macleod discovered that the transforming agent had to be DNA.
Experiment
They performed various experiments and found out that the only
substance, which carried the transforming capability, was DNA because if
the enzyme deoxyriba-nuclease was added to the bacteria, the
transforming capability was lot.
Hershey and Chase's Experiment
Introduction
In 1952, Hershey and chase performed experiment to proof that DNA is a hereditary material.
Experience at Material
Hershey and chase labeled protein coat and DNA of Bacteriophage
separately. Protein coat labeled with radioactive sulphur and DNA with
radioactive phosphorus. These two viruses use to attack bacterial cells.
Steps Experiment
- Hershey and chase observed that if cultures of bacteriophage
are labeled with radioactive phosphorus [P32 labeling DNA] or with
sulphur [S35 for labeling protein coat].
- bacteriophage is ruptured, the DNA is released and
treated with deoxyribsonucleas, the DNA breaks up into fragments in the
solution.
- The empty protein coats of the ruptured membrane appear
as coats all the P32 or S35 were made to inject bacteria and multiply
by the help of special technique, all the S35 labeled protein were
removed.
- The new phage formed contained only P32 indicating the presence of DNA molecule.
Conclusion
The conclusion appears similar to the transforming principle in
bacteria, showing that DNA is the genetic material in phage, transmitted
from one generation to the next.
Watson and Crick's Model of DNA
Introduction
James Watson and Francis crick, in 1953 proposed structure of the DNA molecule.
Structure of DNA
Watson and Crick suggested a ladder like organization of DNA.
1. Double Helix
Each molecule of DNA is made up of two polynucleotide chains which twisted around each other and form a double helix.
2. Backbone of DNA
The uprights of the ladder are made up of sugar and phosphate parts of
nucleotide and the rungs are made up of a paired nitrogenous bases.
3. Pairing of Bases
The pairs are always as follows
- Adenine always pairs with thymine and cytosine with Guanine.
- The two polynucleotide chains are complimentary to each other and held together by hydrogen bonds.
Hydrogen Bonding
There are two hydrogen bonds between Adenine and Thymine (A=T) and three between Cytosine and Guanine (C≡G).
Distance
- Both polynucleotide strands remain separated by 20 Aº distance.
- The coiling of double helix is right handed and complete
turn occurs after 34 Aº. In each turn 10 nucleotide pairs are present,
therefore the distance between two pairs is about 3.4 Aº.
Genes - The Unit of Hereditary Information
Introduction
Archibald Garrod discovered in 1902, that certain diseases were more
prevalent among some families and were inherited as a recessive
Mendelian trait.
Alkaptonuria
Alkaptonuria is a disease in which the urine contained a substance
called "Alkapton" now known as "Homogentisic acid" which was
immediately oxidizes to black when exposed to the air.
Causes
- He suggested that this disease occurred due to absence of an
enzyme, which could break the "Alkapton" down to other products so it
would not build up in the urine.
- He proposed that the condition was "An inborn error of
metabolism" which is occurring due to changes in the hereditary
information, which must have occurred in one of the ancestors of the
affected families.
Conclusion
He concluded that the inherited disorders might reflect enzyme deficiencies.
Genome
Definition
The total genomic constitution of an individual is known as Genome.
Example
In a bacterial cell, a single circular chromosome along with plasmid is
genome of bacteria, while in a human being all twenty two pairs of
autosome along with a pair of sex-chromosomes constitute genome.
Replication of DNA
Definition
The mechanism in which DNA prepares its copies is called DNA replication.
OR
When the formation of new DNA molecule takes place in the cells without any change, it is known as Replication of DNA.
Semi Conservative Replication
Definition
The type of replication in which new daughter double helical duplex
contain one stand old and another newly synthesized is called Semi
Conservative Replication.
The Meselson Stahl Experiment
Introduction
Mathew meselson and Frank Stahl performed experiments to test the semi-conservative method of DNA replication.
Experiment
- They grew bacteria in a medium containing Nitrogen-15 (N15), a heavy isotope of the nitrogen.
- The DNA after several generations became denser than normal because the entire bacterial DNA now contained Nitrogen-15 (N15).
- They then transferred the bacteria into a new medium
containing lighter isotope Nitrogen 14 (N14) and analyzed the cultures
for changes in the DNA.
- At first DNA, which the bacteria synthesized, was all heavy.
- After one round the density of the DNA fell exactly to
the value one half between the all heavy isotope DNA and all light
isotope DNA.
Result
This showed that after one round of replication, each of the daughter
DNA duplex contained one strand of heavy isotope, after two rounds half
contained none of the heavy isotope strand to form light duplex and
half contained one of the heavy strand isotope.
It was now confirmed that the semi conservative method of the replication of DNA replication was true.
One Gene One Enzyme Hypothesis
Introduction
George Beadle and Coworker Edward L. Tatum proved that the information
coded within the DNA of a chromosome, is used to specify particular
enzymes.
Method of Study
- Beadle and Tatum created Mandelian mutation in the chromosomes of the fungus called Neurospora by the use of the x-rays.
- They studied the effect of the mutations caused by them and suggested "One Gene One Enzyme Hypothesis".
Choice of Material
- They choose the bread mold, neurospora crassa as an
experimental organism. It had a short life cycle and was easily grown on
a defined medium, containing known substances, such as glucose and
NaCl.
- The nutrition of Neurospora could be studied by its
ability to metabolize sugars and other chemicals the scientist could
add or delete from the mixture of the medium.
Production of Mutations
- They induced mutations in Neurospora spores by using x-rays.
- The mutated spores were placed on complete growth media
enriched with all necessary metabolites, so keeping the strains alive
because the strains were deficient in producing certain compounds
necessary for fungus growth due to damaged DNA by earlier irradiation,
hence called Mutants.
Identification of Mutant Strains
- To test the mutations, they grew the mutated strains on the
animal media containing sugar, ammonia, salt, a few vitamins and water.
- A strain that had lost the ability to make a necessary metabolite, failed to grow on such media.
- Using this approach, they succeeded in identifying and isolating the different mutants.
Identification of Specific Mutations
- To determine the specific nature of each mutation, they added various chemicals to minimize media, to make the strains grow.
- Using this technique, they were able to pinpoint the biochemical problem and thus the genetic deficiency of the mutants.
- Many of the mutants were unable to synthesize a single amino acid or a specific vitamin.
- If a spore lacked the ability to synthesize a particular
amino acid, such as Arginine, it only grew if the Arginine was added in
the growth medium. Such mutants were called as arg mutants.
- Chromosome mapping studies on the organism facilitated
their work and they mapped three areas clusters of mutant Arginine
genes.
- For each enzyme in the arginine biosynthetic pathway,
they were able to isolate a mutant strain with a defective form of that
enzyme and mutation always proved to be located at one of a few
specific chromosomal sites, different for each enzyme.
Conclusion
They concluded that genes produced effects by specifying the structure
of enzymes and that each gene encodes the structure of a single
enzyme. This was called "One Gene One Enzyme Hypothesis".
RNA
Definition
The single stranded helical polynucleotide contain ribose sugar and uracil instead of thymine is called RNA.
Location
RNA is formed in the nucleus (in nucleolus 10%) as well as in the cytoplasm (90%).
Types of RNA
There are three types of RNA.
1. Ribosomal RNA (rRNA)
The class of RNA found in ribosome is called ribosomal RNA.
Function
During polypeptide synthesis it provides the site on the ribosome where the polypeptide is assembled.
2. Transfer RNA (tRNA)
A second class of RNA is called transfer RNA is much smaller. Human
cell contains more than 40 different kinds of tRNA molecules.
Functions
During polypeptide synthesis tRNA molecules transport the amino acid into the ribosome for the synthesis of polypeptide chain.
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Chapter 3 - Co-Ordination
2nd Year Biology Notes
XII Biology Notes BISE Karachi Chapter 3 - Co-Ordination
Plant Hormones: (Phytohormone)
Definition
Certain chemical produced by plants have profound effect on their
subsequent growth and development. Such chemicals are called Plant
Hormones or Phytohormone.
Phytohormone are synthesized by plants in minute concentration and
exert their effect by activating gene expression or inhibiting enzyme
or changing properties of membrane.
Types of Phytohormone
There are five kind of plant hormones
1. Auxins
2. Gibberellins
3. Cytokinins
4. Abscisic Acid
5. Ethene
1. Auxins
Discovery
the first auxin was discovered by Fret Went in 1926.
Chemical Nature
Indol Acetic Acid (I.A.A)
Indol Acetic Acid (I.B.A)
Nephthalene Acetic Acid (N.A.A)
Site of Synthesis
It is synthesize at the apices of stem and foot, young leaves and young embryo.
Role of Auxin
i. Cell division and cell enlargement
It stimulate teh cell division and cell enlargement and plant in increase the length of plant.
ii. Initiation of Root
Auxins also initiates development of adventitious roots when applied at the cut base of stem.
iii. Abscission
In mature leaves and fruits when auxin production diminishes, a layer
of thin walled cells is formed at the base of petiole and stake of
fruit. This layer is called Abscission layer and causes fall of leaves
and fruit with slight jerk.
iv. Growth of Fruit
Auxins produced in young embryo promotes the growth of fruit.
v. Parthenocarpy
Use of auxin helps in producing parthenocarpic or seedless fruits.
vi. Apical Dominance
Besides growth promoting function on Auxin, also has inhibitory effect
on growth. Growth of apical bud inhibits growth of lateral buds beneath
the stem. This phenomenon is termed as apical dominance removal of
apical buds initiates growth of lateral buds with more leaves and
axillary bud.
vii. Weedicide
Auxins are selective weed killer 2-4 dichlorophenoxy acetic acid (-2-4-D) is used to kill weeds in lawn's and cereal crops.
2. Gibberellins
Discovery
Gibberellins was discovered by T.Yabuta and I.Hayashu in a fungus
called Gibberellins funjikuroi. This fungus causes foolish seedling
(Bakanae) disease in rice. In this disease the infected rice seedling
elongated and ultimately fallover without producing grains.
Chemical Nature
The chemical nature of Gibberellins is Gibberellins acid 70 types of gibberellins have been discovered.
Role of Gibberellins
i. Cell division and cell enlargement
Like auxins Gibberellin also promotes cell division and elongation.
ii. Control of Dwarfism
Gibberellins can control genetic and physiological dwartism plants.
iii. Seed Germination
They promote the synthesis of a-amylase enzyme is dorman seeds due to
the production of this enzyme, the seed starts germination.
iv. Parthenocarpy
These hormones help in the formation of seedless fruit which are called Parthenocarpic fruits.
v. Increase of Crop Yield
The crop yield of sugar can can be increased by the application of gibberellin about 50 tons/ acre.
vi. Formation of Flower and Growth of Pollen Tube
They stimulate flowering and the growth of pollen tubes during fertilization
3. Cytokinins
Discovery
Cytokinins are discovered by Miller in coconut milk.
Chemical Nature
Chemically there are two types of cytokinins.
Kinetin It is found in coconut milk etc.
Zeatin It is found in maize.
Role of Cytokinins
i. Cell Division
They initiate rapid cell division only in the presence of auxin.
ii. Delay in Senescence
They also caused delayed senescence (old age).
iii. Breaking of Seed Dormancy
They break seed dormancy and promote fruit development some species.
4. Abscisic Acid (A.B.A)
In contrast to growth promoting hormones, abscisic acid is growth
inhibitor, produced by plants during adverse environment conditions
such as drought conditions.
Role of Abscisic Acid
- It increases dormancy in buds and seeds.
- It causes stomata to close.
- It turn leaf primordia into scale.
5. Ethene
It is a gas which also acts as a growth inhibitor.
Role of Ethene
- It triggers ripening of fruits.
- It contributes in leaf abscission and also breaks the dormancy of seeds and buds.
- It also initiates flowering in plants e.g. pineapple.
Responses to Environmental Stress
Changes in environmental conditions are the big threats for living
organisms especially for plants. These factors which change the normal
condition of light, CO2, nutrients, temperature etc. causes severe
stresses on plants. The common environmental stresses for plants are
1. Water Shortage (Drought condition)
2. Less Oxygen Supply
3. High Concentration of Salt in the Soil
4. High Temperature
5. Low / Cold Temperature
6. Herbivory / Over Grazzing
1. Water Shortage
- In dry condition, the guard cells of leaf become flaccid to close the stomata.
- In this way the transpiration is stopped.
- The dry condition also stimulates increased synthesis and release of abscisic acid.
- This hormone help in keeping stomata close.
- These plants produce deeper root system.
2. Oxygen Deficiency
- Those plants which grow in wet habitat or marshes, they develop aerial roots to absorb oxygen.
- Some plants developed air tubes that provide oxygen to submerged roots.
3. Salt Stress
- The plants especially halophytes, have salt glands in their leaves where desalination occurs.
4. Heat Stress
In plants there are two methods to tolerate the heat stress.
- Transpiration has a cooling effect on the plant body. By this method the effects of heat are reduced.
- Above 40oC plants cell start synthesizing relatively large quantities of special protein called heat shock proteins.
5. Cold Stress
- Plants respond to cold stress by altering the lipid
composition, changes in solute composition is altered also by producing
different polymers of pentose (Fructose) which allow the crystals to
super cool without compound formation.
6. Herbivory / Over Grazzing
- Plants overcome excessive herbivory by developing horns and production of distasteful or toxic compounds.
Defence Against Pathogens
Diseases of plants may arise from infections by viruses, bacteria or
fungi and other pathogens in most cases. Against these diseases the
plants produce immune system in their body.
First Line Efence
The outer layer epidermis is a protective covering around the body of plant. This is the First Line Defence.
Second Line Defence
When pathogens enter the body through stomata or any other way, then
plants produce certain chemicals to kill them. This is called Second
Line Defence.
Phytoalexins
In infected plants an antibiotic phytoalexins is produced which is effective to all micro-organisms.
Biological Clocks
Definition
A control system is found in all living organisms which controls
physiological and metabolic and metabolic functions according to time
is called Biological Clock.
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Biological Rhythms OR Biorhythms
Definition
In living things the behavior activities occur at regular intervals which are called biological rhythms OR biorhythms.
Circadian Rhythms
Definition
[Circa => about; dies => day]
Biorhythms may occur, showing periodicity of about 24-Hours. These
are called Circadian Rhythm, which means about one day, so they are
also called diurnal rhythms.
Causes of Biorhythm
Biorhythms occurs due to the following reasons.
1. Exogenous Stimuli
2. Endogenous Stimuli
1. Exogenous Stimuli
There may be direct response to various changes in the external (exogenous) stimuli.
2. Endogenous Stimuli
These rhythms can be controlled internally by an efficient time
measuring system and are independent of light and temperature effects.
These types of rhythms are called endogenous.
Co - Ordination
Definition
The working together of all parts of the body or system is called Co-ordination.
Types of Co-Ordination
There are two types of Co-ordination.
1. Nervous Co-Ordination
2. Chemical Co-Ordination
1. Nervous Co-Ordination
Definition
Co-Ordination brought about by the nervous system. It is quickest
way of communication take place by electro-chemical messages called
Nerve Impulse within the body of all animals is called Nervous
Co-Ordination.
Elements of Nervous System
The elements o nervous system which help in co-ordination are
i. Receptor
ii. Central Nervous System (CNS)
iii. Effector
i. Receptor
The sensory tissues or organs which receive any change in their
external as well as internal environment (stimuli) are called
Receptors.
ii. Central Nervous System
The receptors convey the stimuli to the control centre, the nervous system (Central Nervous System) through sensory nerves.
iii. Effector
The central nervous system (CNS) analyses stimuli and sends an
appropriate command, through it motor nerves to either endocrine organ
to release hormones into the blood or to muscles called Effectors.
Pathway in Nervous System
There are two types of pathway in the nervous system.
i. Afferent Nerve Pathway
ii. Efferent Nerve Pathway
i. Afferent Nerve Pathway
From receptor the messages are carried to the Central Nervous System
i.e. brain and spinal cord, this pathway is called Afferent Nerve
Pathway.
ii. Efferent Nerve Pathway
From central nervous system the messages are transferred to the effector. This pathway is called Efferent Nerve Pathway.
Nervous Tissues
There are two types of nervous tissues
1. Neurons
2. Neuroglia OR Glial Cells
1. Neurons
Definition
The nervous system consist of special cells which can generate and conduct electric current are called Neurons.
OR
The chief structural and functional unit of nervous system is called Neurons.
Structure of Neurons
Neurons are different from each other according to size and shape but the structure of neuron consists of three parts.
i. Some or Cell Body
ii. Dendrites
iii. Axon
i. Soma OR Cell Body
Each neuron has a cell body or soma containing nucleus and various
organelle embedded in the cytoplasm. Nissl's granules which are group
of ribosomes, associated with rough E.R. and Golgi apparatus are
present in the cell body.
Functions
- The cell body or soma is the main nutritional part of the cell necessary for growth of neuron.
- Soma receive message to dendrites and convey it to axon.
ii. Dendrites
From the soma, a large number of small threads like terminal branches are arises are called Dendrites.
Functions
- Dendrites receive stimuli and convey it to the soma.
iii. Axon
The unbranched, single elongated cytoplasm process which usually arises opposite to dendrites called Axon.
Axon Hillock
Axon originates from a pyramid like area of soma called Axon-Hillock.
Axon Terminal
At the terminal end of axon many fine branches are present called Axon Terminals.
Myelin Sheath
The axon of some neurons is enclosed by a layer of fatty substance known as Myelin Sheath.
This serve as insulating layer.
Functions
Axon is specialized for conducting impulses to other neurons.
Types of Neurons
According to the function, neurons are of the three types.
i. Sensory Neuron
ii. Motor Neuron
iii. Inter Neuron
i. Sensory Neuron
The neurons which transmit impulses from receptor to the central nervous system is called Sensory Neuron or Receptor Neurons.
ii. Motor Neuron
The neurons which transmit instructions of the central Nervous System
to the effector are called Motor Neurons or Effector Neurons.
iii. Inter Neurons
The neurons present between sensory and motor neurons are called Inter Neurons. They are found in Central Nervous System.
Functions of Neurons
- Neurons is the functional unit of nervous system which receives stimuli, transfers them to the Central Nervous System (CNS).
- It transfers the messages from CNS to the body parts effector.
Reflex Action
Definition
The automatic involuntary responses which occur either due to internal or external stimuli are called Reflex Action.
OR
An immediate response to a specific stimulus without conscious control is called a Reflex Action.
Parts of Reflex Action
Reflex action consists of
i. Receptor: (Skin) receive stimuli.
ii. Sensory Neuron: It carries message from receptor to the Central Nervous System (CNS).
iii. Motor Neuron: It carries message from Central Nervous System (CNS) to the effector.
iv. Effector: (Muscle of gland) which perform action.
Reflex Arc
Definition
The pathway of passage in impulse during a reflex action is called Reflex Arc.
Reflexes may be monosynaptic or polysynaptic.
Monosynaptic
The reflex action in which only one synapse is involved is called Monosynaptic.
Example: Knee Jerk
Polysynaptic
The reflex action in which many synapses are involve due to presence of
inter neurons between sensory and motor neurons is called
Polysynaptic.
Example: Hand withdrawal on the painful stimuli.
Examples of Reflex Actions
- If our hand touch any hot object, it is quickly withdrawn.
- Secretion of juices from the gland.
- Blinking of eyes.
- Contraction and expansion of lungs.
- If a strong light is flashed across the eye, the eyelids are at once closed or start blinking.
Nerve Impulse
Definition
The electrochemical signals developed by a neuron for communication is called Nerve Impulse.
Method of Development of Nerve Impulse
The neurons develop impulse in the following way.
1. Resting Membrane Potential (RMP)
2. Action Potential
3. Propagation of Impulse
4. Synapse
Resting Membrane Potential
Definition
A typical neuron at rest is more positive electrically outside than
inside the cell membrane. This net difference in charge between the
inner and outer surface of a non conducting neuron is -65mv is called
the Resting Membrane Potential.
Factors Involved in Resting Membrane Potential
This popularity is due to the unequal distribution of ions across the
neurolemma. The major factors which are involved in resting membrane
potential are
Sodium and Potassium Ions
- There is a greater concentration of sodium ions outside than inside the membrane.
- Similarly potassium ions are concentrated muscle inside than outside the membrane.
- This is attributed to the activity of ATP driven sodium potassium pump in the neurolemma.
Action Potential
Definition
When neuron is stimulated reversal of the polarity of the neurolemma
occurs, first changes to +40mv and then restores to -65mv again is
called Action Potential.
This action potential is extremely rapid as it occurs in a few milliseconds.
Factors Involved in Action Potential
Sodium and Potassium Ions
- The change in potential across the membrane is due to the presence to sodium and potassium channels in the neurolemma.
Changes Associated with Action Potential
Sequence of membrane potential changes associated with an Action Potential.
- Resting Potential
- Sodium gates open and Na+ diffuses into the cell causing a
depolarization of the membrane from negative to zero and then proceeds
upto +40mv.
- Sodium gates close and potassium gates open.
- K+ diffuses out, causing a repolarization of the membrane.
- Sodium potassium pump restores original ion gradients and resting potential.
Propagation of the Impulse
Definition
When the action potential develops and spreads along the entire length of neurolemma, it is called propagation of nerve.
Synapse
Definition
The region where the impulse moves from one neuron to another is called a Synapse.
Components of Synapse
It consists of three components
1. Pre Synapting Membrane
2. Synaptic Cleft
3. Post Synaptic Membrane
1. Pre Synaptic Membrane
The membrane of axon terminal is called Pre Synaptic Membrane.
2. Synaptic Cleft
The narrow space between neurons is called Synaptic Cleft.
3. Post Synaptic Membrane
The membrane of dendrites of another neuron is called Post Synaptic Membrane.
Motor End Plate
When it is the membrane of muscle cell it is called motor end plate.
Neurotransmitter
The chemicals present in the vesicles which are released at the axon
ending of the neurons, at synapse are called Neurotransmitter.
Mechanism of Impulse Through Synapse
- When an impulse is reached at axon terminals, the calcium channels are opened.
- From synaptic cleft calcium ions are diffused into the calcium channels.
- Due to this synaptic vesicles fuse with the pre-synaptic
membrane, causing the release of neurotransmitter molecules into the
synaptic cleft.
- The neurotransmitter bind to the receptors on the
post-synaptic membrane, which generate action potential in the
post-synaptic cell.
- The neurotransmitters are then reabsorbed by the pre-synaptic cells for reuse.
Examples of Neurotransmitter
Many different types of neurotransmitter are known. These are
acetylcholine, norepinephrine, glycine, gab a, serotonin, dopamine etc.
Evolution of Nervous System
In different group of animals two types of nervous systems can be recognized, which are
1. Diffused Nervous System
2. Centralized Nervous System
1. Diffused Nervous System
Diffused Nervous System is found in cnidarians and Echinoderms.
Nervous System of Hydra
- In these animals, no anterior and posterior ends is present and their body is radially symmetrical.
- The nerves cells are found in the form of network throughout the body.
- The flow of information is not highly directional and it diffuses in all directions.
- The transmission of impulses is slow because of synapses involved.
- There is no brain but the nerve cells constitute the nervous system.
2. Centralized Nervous System
Centralized Nervous System found to varying degrees in more complex
organisms from platyhelminthes to chordates including humans.
Nervous System of Planaria
- In these animals, definite anterior and posterior ends is present and their body is bilaterally symmetrical animals.
- It consists of an anterior brains (a concentration of neurons) which is connected with the Sensory Organs.
- From the brain arise two cord like nerves running longitudinally through the body.
- The two nerve cords are connected with each other at several points through the transverse nerves.
- They co-ordinated the movement of the two lateral sides of the body.
Nervous System of Man
The nervous system of man is the most advanced, highly developed. It
controls all functions of the body. It consists of two parts
1. Central Nervous System (CNS)
2. Peripheral Nervous System (PNS)
1. Central Nervous System (CNS)
Definition
The nervous system consists of brain and spinal cord (hollow nerve
cord) and also consists of upto 100 billion inter neurons is called
Central Nervous System (CNS).
Components of Central Nervous System
The central nervous system consists of
- Brain
- Spinal Cord
Protection of Central Nervous System
Brain and spinal cord both are protected in three ways
i. Cranium
ii. The Vertebral Column
iii. Meninges
iv. Cerebrospinal Fluid (CSF)
i. Cranium
Cranium, which is part of skill, protects the brain.
ii. Vertebral Column
Neural arches of vertebrate of vertebral column protect the spinal cord.
iii. Meninges
Beneath the cranium, the brain and spinal cord are protected by triple layers of tough connective tissues called meninges.
iv. Cerebrospinal Fluid (CSF)
Between the layers of meninges, there is a plasma like fluid which
bathes the neurons of brain and spinal cord is called Cerebrospinal
Fluid (CSF).
It cushions against the bumps and jolts.
2. Peripheral Nervous System (PNS)
Definition
The nerves arises from brain and spinal cord that are spread in
various part of body which transmits the signals between CNS and body
parts make a nervous system called Peripheral Nervous System.
The peripheral nervous system consists of two types of nerves.
i. Cranial Nerves
ii. Spinal Nerves
i. Cranial Nerves
In humans, there are 12 pairs of nerves which arise from the brain or
lead to the brain these nerves are called cerebral or cranial nerves.
ii. Spinal Nerves
In humans, there are 31 pairs of nerves which arise from the spinal cord or lead to the spinal cord are called spinal nerves.
Types of Peripheral Nervous System
The peripheral nervous system is divided into two types according to their functions.
1. Somatic Nervous System
2. Autonomic Nervous System
1. Somatic Nervous System
The peripheral nervous system which controls all the voluntary
activities of the body such as contraction of skeletal muscles and
movement of joint is called Somatic Nervous System.
2. Autonomic Nervous System
The autonomic nervous system which controls involuntary activities of
the body such as smooth muscles, glands, muscles of heart and other
internal organs is called Autonomic Nervous System.
Types of Autonomic Nervous System
Autonomic nervous system divided into two types
i. Para Sympathetic Nervous System
ii. Sympathetic Nervous System
i. Para Sympathetic Nervous System
The autonomic nervous system formed by some cranial nerves, vagus
nerves and the spinal nerves that are arising from the sacral
vertabrate are called Para Sympathetic Nervous System.
ii. Sympathetic Nervous System
The autonomic nervous system whose nerves arise from the thoracic and
lumber regions of spinal nerves is called Sympathetic Nervous System.
Functions
This system is important during emergency situation and is associated
with "flight or fight". It increases the heart beat, breathing rate,
slows digestion, dilates pupil etc.
Brain
Definition
The most important part of Central Nervous System develops from
dorsal, hollow nerve cord well protected in the cranium of skull and
composed of inter neurons and is the seat of our intelligence, learning
and memory is called Brain.
Part of Brain
The brain consists of three parts
1. Fore Brain
2. Mid Brain
3. Hind Brain
1. Fore Brain
Fore brain can be divided into two regions
i. Telencephalon
ii. Diencephalon
i. Telencephalon
The largest part of fore-brain which is differentiated into two cerebral hemisphere or cerebrum is called Telencephalon.
Cerebrum
Cerebrum is the largest part of the brain and is divided into two halves called Cerebral Hemisphes.
Cerebral Hemisphere
Each hemisphere consist of an outer grey matter or cerebral cortex and an inner white matter.
Cerebral Cortex
- Cerebral cortex is the largest and the most complex part of human brain.
- It is highly convulated to occupy the greater number of inter neurons.
Corpus Callosum
The two cerebral hemisphere communicate with each other by means of large band of axons called Corpus Callosum.
Part of Cerebrum
Functionally, the cerebrum is differentiated into four lobes.
- Anterior Frontal Lobe
- Lower Central Temporal Lobe Parietal Lobe
- Dorsal Occipital Lobe
Function of Cerebrum
- Cerebrum is concerned with intelligence memory, learning, resoning and overall control of all voluntary actions.
- It involved in all conscious activities.
- It co-ordinated different senses together.
2. Diencephalon
The diencephalons consists of two parts
i. Thalamus
ii. Limbic System
i. Thalamus
The clearing house for sensory impulses is called Thalamus.
Functions
- It receives them from different parts of brain and relays them to the appropriate part of the motor cortex.
- It also involves in the perception of pleasure and pain.
ii. Limbic System
The limbic system is located in an are between the thalamus and cerebrum.
Parts of Limbic System
The limbic system consists of
i. Hypothalamus
ii. Amygdala
iii. Hippocampus
i. Hypothalamus
Hypothalamus is the part of limbic system which is called Thermostal of the body.
Functions
- The hypothalamus is important in regulation of homeostasis.
- It regulates pituitary gland.
- It also regulate body temperature, blood pressure, hunger, thirst, aggression, pleasure and pain.
ii. Amygdala
The amygdala produces sensation of pleasure, punishment or sexual arousal stimulation.
It also involve in the feelings of fear.
iii. Hippoc Ampus
Hippocampus is involved in long term memory.
Mid Brain
In mammals mid brain is relatively very small. It consists of the optic lobes which are represented by four small bodies.
Functions
It receives sensory information like vision, odour etc. It receives
sensory information from spinal cord and sends them to the fore brain.
Hind Brain
Hind brain consists of
1. Medulla Oblongata
2. Cerebellum
3. Pons
4. Reticular Formation
1. Medulla Oblongata
Medulla oblongata lies on the top of spinal cord.
Function
- It controls involuntary actions like blood pressure, heart
beat, sneezing, coughing, breathing rate, hicupping, swallowing etc.
2. Cerebellum
The cerebellum lies dorsally behind the optic lobes. It is highly convoluted. It is large in mammals than other animal.
Functions
- The cerebellum plays an important part in controlling muscular co-ordination.
- It specially maintains balance and also position of the body in space.
3. Pons
Pons regulates activities like muscular co-ordination, facial expressions, breathing and sleeping.
4. Reticular Formation
Reticular formation lies in pons, medulla and mid brain.
Functions
- It monitors the messages to the brain which should be ignored or should be realized.
Brain Stem
The oldest tissues formed by the combination of medulla oblongata, pons and mid brain is called as Brain Stem.
Functions
- It involved in the control of sleep and wakening.
Spiral Cord
Definition
A thick whitish nerve cord that lies below the medulla oblongata and
extends down through the neural canal of vertebrate upto the hips is
called Spinal Cord.
Cross Section of Spinal Cord
In cross section, the spinal cord is differentiated into two areas.
- White Matter
- Gray Matter
Unlike brain, spinal cord has grey matter inside surrounded by
white matter on the outside. They grey matter has the shape of an "H".
The first synapse of each sensory neuron is located in the grey matter.
Central Canal
The narrow central containing cerebrospinal fluid runs through the
middle of the spinal cord. This fluid brings nutrients to the spinal
cord.
Spinal Nerves
The nerve arises from spinal cord is called Spinal Nerves.
- Each spinal nerve divides into two roots just before it joins spinal cord.
1. Dorsal Root
2. Ventral Root
1. Dorsal Root
The dorsal root joints the dorsal part of the spinal cord and it contains axons of sensory neurons.
Dorsal Root Ganglion
The cell bodies of these neurons aggregate in a small swelling known as the dorsal root ganglion.
2. Ventral Root
The ventral root which is attached to the ventral part of the spinal
cord carrying axons of motors neurons, arised from the spinal cord.
Functions of Spinal Cord
- Spinal cord serves as an express way for signals between autonomic nervous system.
- It is also the control centre for many reflexes.
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Receptors
Definition
The single or group of either modified neurons or epithelial cells
which receive stimuli either from external environments and relaying
them in the form of impulses to the CNS are called Receptors.
Receptionists
The receptors are acts as receptionist of nervous system because they
receive any kind of change, which is then transferred to the brain and
spinal cord.
Sensation
Receptor converts stimuli into nerve impulses, this stage awareness of stimulus is called Sensation.
Perception
In the control centre of the nervous system, the impulses are converted into perception.
Types of Receptors
Receptors are classified according to type of stimulus which they can
detect and give response. Following are some types of receptor.
1. Thermoreceptor
The receptors which detect and respond to temperature fluctuations (heat and cold) are called Thermoreceptor.
2. Chemoreceptor
The receptors which can detect and respond to presence of certain chemicals in their surrounding are called Chemoreceptor.
3. Mechanoreceptor
The receptors which can detect the stimuli of sound, motion, touch, pressure gravity and movement are called Mechanoreceptor.
4. Photoreceptor
The receptors which respond to the stimulus of light and ultraviolet rays are called Photoreceptor.
5. Pain Receptor
The receptors which produced sensation of pain or damage tissues are called the Pain Receptor.
Working of Sensory Receptors in Skin
In human, the receptors in skin are concerned with at least five different senses i.e., touch, pressure, cold, warm and pain.
Types of Sensory Receptor in Skin
There are two types of sensory receptors in the skin.
i. Free Nerve Ending Receptors
ii. Encapsulated Receptors
i. Free Nerve Ending Receptors
The simplest types of receptor which contain free end without any
protective capsule and are located just beneath the epidermis are
called Free Nerve Ending Receptors.
Functions
Free nerve ending receptors adapt very slowly to stimulation.
Types
They are of different types
a. Mechanoreceptors Receive touch and pressure.
b. Nociceptors Feel pain
c. Thermoreceptors Feel change in temperature
ii. Encapsulated Receptors
The type of receptor contain a protective capsule of connective tissues
at their ends and lie in skin are called Encapsulated Receptors.
Types
Encapsulated receptor are of following two types
i. Meissner's Corpuscles
ii. Pacinian Corpuscles
i. Meissner's Corpuscles
The encapsulated receptors that are found in those parts which do not
have hairs such as finger tips, eyelids, lips palms, soles, nipples etc
are called Meissner's Corpuscles.
Structure of Capsule
Their capsules consists of thick collagen fibers with spiral and highly coiled nerve endings.
Function
There are touch receptors means very sensitive to touch.
ii. Pacinian Corpuscles
The encapsulated receptors which are found in dermis layer and also in
some internal organs and moveable joints are called Pacinian
Corpuscles.
Structure
Their nerve endings are surrounded by an onion like capsule made of
concentric layers of membrane. Between the membranes fluid filled
spaces are present.
Functions
They are pressure receptor and detect rapid and deep pressure changes produced by vibration and touch.
Sensory Receptors with Reference to Arteries
The aortic arch and the carotid artery contain many receptor which are
Mechanoreceptor
They detect the pressure changes in arteries.
Baroreceptor
They detect the pulse pressure
Function
These receptors transfer these changes to the medulla oblongata which controls blood pressure.
Aortic Body and Carotid Body
The aortic arch and the carotid sinus also contain chemoreceptor called Aortic body and carotid body.
Function
They are sensitive to CO2 concentration and hydrogen ion concentration of the blood.
composition, changes in solute composition is altered also by producing
different polymers of pentose (Fructose) which allow the crystals to
super cool without compound formation.
depolarization of the membrane from negative to zero and then proceeds
upto +40mv.
membrane, causing the release of neurotransmitter molecules into the
synaptic cleft.
post-synaptic membrane, which generate action potential in the
post-synaptic cell.
beat, sneezing, coughing, breathing rate, hicupping, swallowing etc.
__________________________________________________________________________________
Effects of Drugs on Co-Ordination
Drugs
A chemical substance that causes the specific physiological response in the body are called drugs.
Importance
- Many drugs are useful medically to treat emotional stress or certain illness.
- Drugs which people take to alter the mood or emotional
state affect body functional interfering with the working of
neurotransmitters.
- Therefore their abuse often causes harmful effects.
Nicotine
- It is a drug found in tobacco.
- It acts as a stimulant and is widely used as a neurological agent.
- Nicotine affects post synaptic membrane in CNS and PNS.
- It minimize the action of acetylcholine on nicotine receptors. So it is stimulant to nerve impulse.
- It increase the heart beat, rate, blood pressure and digestive tract mobility.
- Nicotine may induce vomiting and diarrhea.
- It may cause water retention relation by kidneys.
- It stimulate the nervous system thereby reducing fatigue, increasing, alertness and improving the concentration.
Nervous Disorders
The abnormalities appear in brain, spinal cord, central nervous system
and peripheral nervous system causes diseases called Nervous
Disorders.
Some common disorders of nervous system are as follows
1. Parkinson's Disease
2. Alzheimer's Disease
3. Epilepsy
1. Parkinson's Disease
It is a brain disorder.
Causes
It either caused by degeneration or damage of nerve tissues within the basal ganglia of the brain.
Symptoms
It is characterized by involuntary tremors, diminishing motor power and
rigidity. It causes stiffness, weakness and trembling of the muscles.
The mental faculties are not affected.
Treatment
Leopoda is the effective medicine which is helpful in minimizing the
symptoms by can not halt the degeneration of neurons of brain.
2. Alzheimer's Disease
It is the progressive degeneration of neurons of brain, especially cortex and hippocampus.
Causes
There is a genetic pre-disposition to the disease in some people, so it tends to run in families.
Stages of Diseases
The disease progresses in three broad stages.
First Stage
At first, the patient notices his forgetfulness.
Second Stage
In second phase, there is a severe loss of memory particularly for
recent events. Anxiety increases with sudden changes in mood.
Third Stage
In the third and last stage the disease become severe. He losses
memory, hears voices or see faces in the absence of any person. This
disease is called Hallucination. He does not share his ideas and does
not accept ideas of other persons, such disease is called paranoid
delusions.
Symptoms
The main symptom of the disease is the loss of memory called dementia.
Treatment
- Effective medicines should be used.
- Psychological treatment is better to control the disease.
- Personal care of patient is necessary otherwise he may get any harm.
Chemical Co-Ordination
Definition
The co-ordination brought about by the endocrine gland system. It is
not very rapid, but shows slow and prolonged effect takes place by
chemical substances called hormones and neurotransmitter within the
body of all animals is called Chemical Co-ordination.
Endocrine glands secreat their secretions (hormones) directly into the
blood stream. They are transported by the blood to the target cells.
Types of Hormones
Chemically the hormones are organic compounds which are classified into three types.
1. Peptide Hormones
2. Modified Amino Acids Hormones
3. Steroid Hormones
1. Peptide Hormones
The hormones which are composed of protein are called Peptide Hormone. There are two types of peptide hormones.
i. Small Chain Amino Acids
ii. Large Chain Amino Acids
i. Small Chain Amino Acids
The peptide hormones consists of small chain of amino acids are called Small Chain Amino Acids.
Examples
- Glucagon
- Antidiuretic Hormone (ADH)
- Oxytocin
ii. Large Chain Amino Acids
The peptide hormones consists of long chain of amino acids are called Large Chain Amino Acids.
Example
- Insulin
- Preleclin
2. Modified Amino Acid Hormones
The hormones consists of modified amino acids are called Modified Amino Acid Hormones.
Example
- Thyroxine
- Epinephrine
- Nor-epinephrine
3. Steroid Hormones
The hormones which are composed of lipid are called Steroid Hormones.
Example
- Estrogen
- Progesterone
- Testosterone
- Aldisterone
Hormone Action
To explain the action of hormones two models have been proposed.
1. First Model
2. Second Model
Similarity Between Both Models
Both model agree that the plasm membrane of cells contain certain receptors to accept the hormones.
Dissimilarity Between Both Models
After receiving the hormones continue their way of action called signal transduction pathway. It is different in both models.
1. First Model
According to the first model peptide hormones are involved. The
receptor molecule is attached to an enzyme adenylate cyclase in the
inner part of plasma membrane. The hormone is attached to the receptor.
By the activity of enzyme ATP molecule is changed into cyclic adenosine
monophosphate (AMP) in the cytoplasm. The cyclic (AMP) acts as a
second messenger and activates the particular enzyme which actually
helps in the function. Some other messenger molecules also take part in
the process.
2. Second Model
According to the second model, steroid hormones are involved. These
hormones are fat soluble, so they enter the cell directly through the
plasma membrane, so they do not need second messenger. In the cytoplasm
they are attached to the particular receptors which transfer into the
nucleus. In the nucleus. In the nucleus hormone receptor complex
activities the genes due to which actual function is started.
Functions of Hormones
- They do not initiate new biochemical reactions but produce
their effects by regulating the enzymatic and other chemical reactions,
already present.
- They may either stimulate or inhibit a function.
- Hormones may also control some long term changes, such as rate of growth, rate of activity and sexual maturity.
Endocrine System
Definition
Endo => Inside => Krinein => separate i.e. to secrete.
In the body of vertebrates there are certain dustless gland which
poured their secretions (hormones) directly into the blood or in body
fluids are called endocrine glands or ductless glands constitute a
system called Endocrine System.
Endocrine Glands of Man
In the body of man and other mammals, following important endocrine glands are mostly found.
1. Hypothalamus
2. Pituitary Gland
3. Thyroid Gland
4. Parathyroid Gland
5. Pancreas
6. Adrenal Gland
7. Thymus Gland
8. Pineal Gland
9. Gonads
1. Hypothalamus
The part of forebrain which forms a connection between Nervous System and endocrine system is called Hypothalamus.
Hormones
The hypothalamus contains specialized nerve cells called neurosecretory cells which produced two types of hormones.
i. Releasing Hormone
ii. Inhibitory Hormone
i. Releasing Hormones
The hormones which are produced to increase the secretion of another glands are called Releasing Hormones.
Function
Releasing hormone control the secretion of hormones from pituitary gland.
ii. Inhibitory Hormones
The hormones which are produced to prevent the extra secretion of hormones are called Inhibitory Hormones.
Function
Hypothalamus produced two hormones which are
- Oxytocin
- Antidiuretic Hormones (ADH)
These two hormones are stored in the posterior lobe of pituitary gland.
2. Pituitary Gland (Hypophysis)
Pituitary gland is called "master gland" because it controls the secretion of other endocrine glands.
Location
The pituitary gland is located in the brain. It is attached to the base of hypothalamus by short.
Size
The pituitary gland is small pea size gland.
Lobes of Pituitary Gland
Pituitary gland has three lobes
i. Anterior Lobe
ii. Median Lobe
iii. Posterior Lobe
i. Anterior Lobe
Anterior lobe produces three types of hormones which are
a. Tropic Hormone
b. Growth Hormone or STH
c. Prolactin
a. Tropic Hormone
The hormones which control the activity of other hormones are called Tropic Hormones.
Kinds of Tropic Hormone
The tropic hormone secreted by the pituitary gland are as follows
Thyroid Stimulating Hormone (TSH)
It control the working of thyroid gland including secretion of thyroxin.
Adreno-Cortico Tropic Hormone (ACTH)
In controls the activity of outer part of cortex of adrenal gland.
Follicle Stimulating Hormone (FSH)
FSH in females stimulate follicle developing and secretion of oestrogens from the ovaries.
In males it stimulates development of the germinal epithelium of the testis and sperm production.
Leutinizing Hormone (LH)
This hormone helps in the formation of sperms and testosterone hormone
in male. In female it takes part in ovulation i.e. release of ovum from
the ovary.
b. Growth Hormone OR Somatotropin Hormone (STH)
It regulates the normal growth by controlling many metabolic processes,
such as protein synthesis, involved in growth of bones and soft
tissue.
c. Prolactin Hormone
This hormone stimulate mammary glands and production of milk.
ii. Median Lobe
Median lobe produced one hormone called Melanocyte Stimulating Hormone (MSH).
Functions
This hormone controls darkening of skin in many vertebrates. In human,
very small amount of MSH is produced by the anterior pituitary rather
than median.
iii. Posterior Lobe
From posterior lobe of pituitary gland following hormones are secreted.
a. Antidiuretic Hormone (ADH)
b. Oxytocin
a. Antidiuretic Hormone (ADH)
It stimulates the re-absorption of water by tubules of kidney and thus decreases the amount of urine passed.
b. Oxytocin It stimulates contraction of muscles of uterus during child birth and release of milk during breast feeding.
Abnormal Conditions Due to Pituitary Gland
Due to abnormal production of somato tropic hormone (STH) or growth hormone, following abnormalities occur.
i. Gigantism
ii. Dwarfism
iii. Acromegaly
i. Gigantism
It is disease of childhood.
Causes
It occurs due to over secretion of somatotropic hormones (STH) or growth hormone.
Symptoms
The affected individuals becomes abnormally tall.
ii. Dwarfism
It is a disease of childhood.
Causes
It caused due to less secretion of somato tropic hormone or growth hormone.
Symptoms
The affected individuals becomes abnormally short.
iii. Acromegaly
It is a disease of adulthood.
Causes
It occurs due to overproduction to somatotropic homrone (STH).
Symptoms
In this condition, hands, feet and jaw bones and cartilages and soft muscles become larger in size and swollen.
3. Thyroid Gland
Location
Thyroid gland is located in the neck region in front of trachea. It consists of two lobes, one on either side of trachea.
Shape
It is butterfly in shape.
Secretions
It secreats three main main hormones.
i. Thyroxine or T4 (Tetra lodo Thyroxine)
ii. T3 (Tri lodo Thyroxine)
iii. Calcitonin
i. Thyroxine OR T4
- Thyroxin increases the metabolic rate and promotes both physical growth and mental development.
- It increases the oxygen consumption and production of heat.
ii. T3 Hormone
- Tri lodo thyroxine performs the same function as that of thyroxine or Tetra lodo Thyroxine.
iii. Calcitonin
- Calcitonin plays and important role in calcium homeostasis.
- Calcitonin is produced when calcium Ca++ level is increased in blood.
- It respond to decreased the blood calcium level by stimulating the deposition of excess calcium in bones.
Abnormalities of Thyroid Gland
There are two conditions of abnormalities of Thyroid Gland.
i. Hyperthyroidism
ii. Hypothyroidism
i. Hyperthyroidism
The state of over secretion of hormones by thyroid gland is called Hyperthyroidism.
Due to hyperthyroidism following symptoms usually appear.
- High blood pressure
- Increase body temperature
- Intolerance to heat
- Profuse sweating
- Loss in weight etc
ii. Hypothyroidism
The state of deficiency of T4 and T3 hormones is called Hypothyroidism.
It causes following diseases
i. Myxedema
ii. Goiter
iii. Cretinism
i. Myxedema
It occurs in adult stage.
Causes
It occurs due to the deficiency of T3 and T4 Hormones
Symptoms
Myxedema produces following symptoms
- Overweight (Obesity)
- Loss of hairs
- Dry Skin
- Mental activity or body movement become slower
- Intolerance to cold
ii. Goiter
Causes
It occurs due to deficiency of iodine in diet which results in decreased level of thyroxin hormones (T3 and T4).
Symptoms
- Thyroid gland works more than normal to produce more thyroxine. As a result of which they become swollen and enlarged.
iii. Cretinism
It is disease of childhood.
Causes
It occurs due to deficiency of thyroxin hormone in early age, such
persons are called cretinism and the mechanism is known as cretinism.
Symptoms
This disease shows following symptoms
- Mental retardation
- Stunted growth
- Physical weakness
- Abnormal facial features
4. Parathyroid Gland (PTG)
Location
Parathyroid glands are present in the neck regiort with two parts of thyroid gland.
Size
Their size is like pea seeds.
Secretion
Parathyroid gland secrete only one hormone called Parathyroid Hormone (PTM).
Function
- Parathyroid hormone plays an important role in calcium's homeostasis.
- Parathyroid hormone is produced when calcium Ca++ level is decreased in blood.
- It response to increased the calcium ion in blood in two ways.
- It increase the absorption of calcium ions in kidney.
- It induces the bone cells (Osteoblasts) to released
calcium from bones into the blood. This process is called
Demineralization.
Abnormalities of Parathyroid Gland
Abnormalities in parathyroid gland usually produces two diseases.
i. Tetany
ii. Rickets
i. Tetany
Deficiency causes a drop in blood Ca++ which in turn leads to muscular tetancy.
ii. Rickets
Over production would lead to a progressive demineralization of the
bones similar to tickets, as well as to the formation of massive kidney
stones.
5. Pancreas
Pancreas is a gland which acts as both exocrine and endocrine gland.
Location
Pancreas is located in abdominal cavity below the liver.
Islets of Langerhans
The cells of pancreas are called Islets of langerhans.
- They perform the function of endocrine gland.
- This is under control of the pituitary trophic hormones
STH and ACTH and responds directly to the level of blood glucose which
is normally 90ms/100mg.
- The islets of langerhans are of two distinct types.
i. Alpha Cells
ii. Beta Cells
i. Alpha Cells (α-cells)
Alpha cells secreat hormone called Glucagon.
ii. Beta Cells (β-cells)
Beta cells secreat hormone called Insulin.
Glucagon
- It is secreted in response to decrease sugar level in blood.
- It increase the blood glucose level mainly by promoting breakdown of glycogen to glucose in the liver and muscles.
- It also increase the rate of breakdown of fats.
Insulin
- It is secreted in response to increase sugar level in blood.
- It decrease the blood glucose level mainly by following mechanism:
i. It increases glycogen synthesis in liver and also increasing cell utilization of glucose.
ii. It also stimulates both lipid and protein synthesis which reduces glucose level.
iii. Insulin inhibits the hydrolysis of glycogen in the liver and muscles.
Disorders of Insulin Deficiency
Due to deficiency of insulin, a diseased appeared called Diabetes mellitus.
Diabetes Mellitus
When there is deficiency of insulin, the amount of sugar is increased in blood, it is called Diabetes Mellitus.
Symptoms
- High level of blood sugar
- Sugar in the urine
- Disturbance of the body's osmotic equilibrium
- Dehydration
- Derangement of the nervous system
Types of Diabetes Mellitus
There are two types of Diabetes Mellitus.
i. Insulin Dependent Diabetes
ii. Insulin Independent Diabetes
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6. Adrenal Gland
Location
A pair of adrenal gland is present, one on the top of each kidney.
Structure
Each adrenal gland has two distinct parts
1. Adrenal Cortex
2. Adrenal Medulla
1. Adrenal Cortex
The outer layer of adrenal gland is called Adrenal Cortex. It is
controlled by the adrenocorticotropic hormone (ACTH) secreted from
Pituitary Gland.
Secretions
Adrenal cortex produces many hormones which are collectively called as Corticosteriods.
Functions
- These hormones are very important for regulating carbohydrates metabolism.
- They are also essential for maintaining mineral balance in the body.
- The important corticosteroid hormones are as follows.
1. Cortisol
2. Aldosterone
3. Androgen
1. Cortisol
- This hormone is produced at the time of fever and diseases.
- It converts protein of muscles into amino acids, which are changed into glucose by the activity of liver.
- In this way there is continue supply of energy in the body.
- It reduces pain and inflammation in the body.
Over Secretion of Cortisol
Over secretion of cortisol causes a disease called Cushing's Syndrome.
Cushing's Syndrome
Symptoms
- Obesity
- Breakdown of Muscles
- Diabetes
Deficiency of Cortisol
Deficiency of cortisol causes a diseases called Addison's Disease.
Addison's Disease
Causes
It is due to defect in auto immune system.
Symptoms
- Loss in weight
- Weakness
- Low level o sugar
- Low blood pressure
Aldosterone
- This hormone helps in the reabsorption of Na++ and Cl- ions by the help of kidney.
- It raises the blood pressure and blood volume.
Androgen
- It causes development of the secondary male characteristics,
such as hairs on face, depending of voice and increase in muscle size.
It is like a testosterone.
- When their amount in female in increased, hairs are produced on the face of female.
2. Adrenal Cortex
The inner layer of adrenal gland is called Adrenal Medulla.
- Adrenal medulla works under the influence of sympathetic nervous system.
Secretions
Adrenal Medulla produces many hormones which are collectively called as
Emergency Hormones. Both are secreted in stress situation.
The important emergency hormones are
i. Adrenaline OR Epinephrine
ii. Nor-Adrenaline OR Nor-Epinephrine
i. Adrenaline OR Epinephrin
- It increase heart rate, amount of glucose in blood, rapid respiration and metabolism during emotions and emergency.
- It also takes part in the contraction of blood vessels in intestine and dilation of blood vessels in muscles.
ii. Non-Adrenaline Or Nor-Epinephrine
- It also functions like epinephrine, but its main function is control of blood pressure during fight and flight.
- The over secretion of both these hormones causes high blood pressure.
7. Thymus Gland
Location
It is present in the upper region of thorax, behind the breast bone. It
consists of two parts which are attached together in the front region
of trachea.
Structure
It secret hormone called Thymosine.
Function
Thymosine controls the production of Thymphocytes and also their
differentiation. These are the cells of immune system and control the
infection of virus bacteria.
8. Pineal Gland
Location
Pineal gland is a tiny gland present at the upper side of diencephalons in the brain.
Secretion
Pineal gland secretes a hormone called Melatonin.
Functions
- Metatonin regulates the seasonal reproductive cycles.
- It also regulates the growth and development of gonad in many mammals.
- It controls the sensation of light and darkness of eyes.
- It produced a/c to the time of day, night or weather.
8. Gonads
The testes and ovaries also functions as endocrine glands and produce
sex hormone chemically sex hormones are steroids. Secretion of gonadial
hormones is controlled by gonadotropic hormones pituitary gland.
i. Testes
Testes are the male reproductive organs.
Secretion
Testes produced male sex hormone called Testosterone.
Functions
- Tests is responsible of sexual maturity and development of
secondary sexual characts such as appearance of beard and moustache in
males.
- It also stimulates the growth of bones and muscles.
ii. Ovaries
Ovaries are female reproductive organs but they acts as endocrine glands.
Secretion
Ovaries secrete two hormones called as
i. Oestrogen
ii. Progesterone
i. Oestrogen
Oestrogen causes development of female secondary sexual characters.
It also helps in thickening of the wall of uterus and prepare it for implantation of fertilized ovum.
ii. Progesterone
It is concerned with maintenance of pregnancy by preventing the contraction of walls of uterus
Chapter 3 - Co-Ordination 2nd Year Biology Notes XII Biology Notes BISE Karachi Chapter 3 - Co-Ordination Plant Hormones: (Phytohormone)...