Chapter 1
Shorts
Question Answers – Homeostasis
Q.1. Why more water is required for the
excretion of ammonia.
Ans. It is highly soluble in water
and rapidly diffuse across the plasma membrane. Ammonia is toxic for the
organism. Its toxicity is reduced when diluted with large quantities of water
due to this reason more water is required for excretion.
Q.2. Where urea is produces and why ATP is
required for the process?
Ans. Urea is produced in the liver.
NH3 combines with CO2 during this process ATP is required. Mammals, amphibians,
shark and some bony fishes also excreted urea.
Q.3. Why water is not required for the
excretion of uric acid?
Ans. It has extremely low solubility
in water due to this water is not required for the excretion of uric acid.
Formation of uric acid requires ATP.
Q.4. In which form the uric acid is
excretion out of the body?
Ans. The suspension of uric acid is
discharged in the form of thick paste or solid pellets. Uric acid is excreted by
insects reptiles and bird.
Q.5. How much urea is less soluble than
ammonia in water?
Ans. Urea is relatively less soluble
in water 100,000 times less toxic than NH3.
Q.6. Give the route of excretion from the
soft bodied animals and fishes?
Ans. In soft bodied animal ammonia is
excreted from the body surface. In fish, most of the ammonia is excreted
through gills as ammonium ions.
Q.7. What are the excretory organs of
earthworm?
Ans. The excretory organs of
earthworm are metanephridia which are arranged segmentally.
Q.8. What is metanephridium?
Ans. Each metanphridiumus coiled tube
which is surrounded by capillaries. One end of metanephridium open in coemolic
fluid where as other end opens on body surface through nephridiopore. Waste
materials along with water are absorbed from the coemolic fluid passes through
coiled part reabsorption of water takes place and remaining part is excreted
through nephridiopore to outside the body.
Q.9. What is liver?
Ans. Liver is large reddish brown
exocrine gland located in abdomen just below the diaphragm. Liver has bladder
like gall bladder which stores bile and pour this bile into duodenum by the
help of bile duct.
Q.10. What is the role of the liver for the
metabolism of carbohydrates?
Ans. Liver maintain the level of
glucose in blood. If blood contains excess glucose then glucose is stored in
liver in the form of glycogen. If blood contains less glucose then stored
glycogen is converted in glucose and release in blood. If glycogen is
unavailable then liver converts amino acid or lipids into glucose and release
in ton blood. Liver also converts lipids into fats and stores it.
Q.11. What is deamination and in which cycle
the ammonia is converted into urea?
Ans. In liver break down of amino
acids takes place. First amino group (NH4) is separated from amino acids and
this process is called diamination then CO2 reacts with ammonia in ornithine
cycle and converted into urea. This urea is released in blood circulation and
excreted through kidneys.
Q.12. Describe the detoxification role of
liver?
Ans. Liver also neutralizes many
toxic substance such as hydrogen peroxide which is produced during metabolism
is broken down into H2O and O2 by the help of enzyme catalase.
Q.13. How gall stones are formed?
Ans. Liver synthesizes cholesterol in
excess amount forms gall stones in gall bladder.
Q.14. How liver help in the maintenance of
body temperature for homeostatis?
Ans. Due to high metabolic are in
liver heat is produced which helps in maintaining body temperature.
Q.15. For which vitamins the liver act as a
reservoir?
Ans. Liver also stores many vitamins
such as A, B and D.
Q.16. What is ultrafiltration and where it
occurs?
Ans. During this process when blood
passes through glomerulous, its plasma filters and diffuses into Bowman’s
capsule. Filtration occurs due to high hydrostatic pressure in glomerulous is
called ultrafiltration. This filtrate contains all molecules except plasma,
proteins and blood cells.
Q.17. From where the reabsorption of
glucose, amino acid, water and salt occur in the nephron?
Ans. When filtrate passes through
proximal convoluted tubule, glucose, amino acids, water and salts are
reabsorbed in per tubular network.
Q.18. Compare the role of ascending and
descending limb of henel?
Ans.
Ascending Limb Of Loop Of Henle
In ascending limb of loop of Henle
active absorption of sodium and chloride ions takes place. Sodium and chloride
ions move out from filtrate into interstitial fluid and then taking up by the
blood.
Descending Limb Of Loop Of Henle
When filtrate passes through
descending limbs of loop of Henle reabsorption of water and sodium takes place.
Q.19. What is the function of distil
convoluted tubule of nephron?
Ans. In distal convoluted tubule
concentration of various salts in adjusted under influence of hormones. The
filtrate now almost urine and collected in collecting dust.
Q.20. How many types of counter current
mechanism are there?
Ans. There are two counter current
system are operating.
1. One of the counter current is
termed as counter current multiplier loops of Henle.
2. The other counter current system
is consists of those blood vessels which run parallel to loop of Henle and are
called Vasa Recta.
Q.21. How counter current multiplier perform
its responsibilities?
Ans. In counter current multiplier
loops of Henle the filtrate passes through descending limbs of loop of Henle,
reabsorption of water takes place from filtrate and it becomes hypertonic then
the interstitial fluid. In ascending limb of loop of henle, sodium and chloride
ions are actively reabsorbed from the filtrate and it becomes hypotonic. Sodium
and chloride ions removed from ascending limbs slowly diffuse bact to descending
limbs.
Q.22. What is the role of vasa recta?
Ans. The outer counter current system
is consists of those blood vessels which run parallel to loop of Henle and are
called Vasa Recta. The blood supply to vasa recta provides oxygen and
nourishments to the tissues of medulla it also takes away water absorbed from
the filtrate.
Q.23. What are the adaptations of kidneys
for the conservation of water?
Ans. Kidneys are adapted for the
conservation of water. For this purpose two types of nephrons are found in
kidneys. Such as cortical nephrons which have sorter lop of henle where the
reabsorption of water is lower and Juxtamedullary nephrons which have longer
loop of henle which extend up to medulla. In these nephrons reabsorption of
water is higher. If kidney has larger number of Juxtamendullary nephrons there
is greater conservation of water.
Q.24. How many types of nephrons are there?
Ans. There are two types of nephrons.
1. Cortical Nephrons: Which have
shorter loop of Henle where the reabsorption of water is lower.
2. Juxtamedullary Nephrons: Which
have longer loop of Henle which extend up to medulla. In these nephrons
reabsorption of water is higher.
Q.25. How ADH increase the reabsorption of
water?
Ans. A hormone ADH (Antidiuretic
hormone) or vasopressin which increases the permeability of collecting duct in
this way reabsorption of water increases.
Q.26. Which hormones are responsible for the
reabsorption of sodium ions and calcium ions?
Ans. Another hormone Aldosterone
which is secreted from adrenal gland increases the reabsorption of sodium ions
Parathormone secreted from parathyroid glands maintains the level of calcium
after increasing reabsorption of calcium ions.
Q.27. What is the percentage of infective
renal stones and what is their biochemical compositions?
Ans. About 20% of calcium are termed
as infective stones. Such calculi consists of combination of calcium, magnesium
and ammonium phosphate. Some stones about 5% are formed by uric acid.
Q.28. What is lithotripsy?
Ans. It is the advance method of
removing stones from kidneys and urinary bladders. In this method shock waves
and ultra sonic waves are used for breaking stones in the body. After being
broken small broken fragments of are passed in urine.
Q.29. What is renal failure and what are
their major signs and symptoms?
Ans. It is the condition in which
kidney are unable to filter blood to remove waste materials. In this way waste
materials accumulate in blood, which leads to symptoms such as nausea, vomiting
loss of appetite, weakness, breathlessness etc. In severe cases coma and death.
Q.30. What is haemodialysis?
Ans. Haemodialysis means “cleaning
the blood”. In this procedure blood is circulated through a machine which
contains a fluid dialyzer whose composition is mentioned.
Q.31. How many types of dialysis are there?
Ans. There are two types of dialysis
1. Haemodialysis
2. Peritoneal dialysis
Q.32. How haemodialysis is carried out?
Ans. Dialyzer has two spaces
separated by their semipermeable membrane. Blood passes from one side of the
membrane and dialyzer on the other side. The wastes and excess water pass from
the blood through the membrane into the dialyzer. There after the blood is
returned to circulation.
Q.33. What peritoneal dialysis?
Ans. During this method, there is
inserted in the peritoneal cavity of abdomen after making an incision. Through
this cathoter dialyze is filled in to the peritoneal cavity for several hours.
As a consequen waste from the blood vessels lining the peritoneal cavity seep
through peritoneal membrane into the cavity and mixes with dialyzer. The fluid
is then drain out through the catheter.
Q.34. What is thermoregulation?
Ans. The regulation of body
temperature within the stable normal constant limits of the body against the
harsh fluctuating circumstances for the maintenance of homeostasis is called
Thermoregulation.
Q.35. How many types of thermoregulation?
Ans. Thermoregulation among animals
of two types.
1. Behavioral Thermoregulation
2. Physiological Thermoregulaton
Q.36. What is behavioural thermoregulation?
Ans. This regulation involves
behavior of the animals in hot and cold weathers for e.g. animal increases or
decreases heat loss by changing their locations. They will bask in the sun or
in warm rock during winter and find wet cool area in summer.
Q.37. What is physiological
thermoregulation?
Ans. Its involves the regulation of
body temperature by some biological means. It is exhibited by the change in
blood circulation, body metabolism, heat loss by evaporation of sweat.
Q.38. What are Poikilotherms?
Ans. Those animals which change their
body temperature with respect to the change of temperature of surroundings.
e.g. all invertebrates, fishes, amphibians and reptiles fall into this
category.
Q.39. What are Homotherms?
Ans. Those animals which have
constant body temperature which is independent to the changes in the
temperature of surroundings.
Q.40. What are Ecotherms?
Ans. Those animals which maintain
their body temperature by absorbing heat from the environment. E.g. Lizard
basking in the sun.
Q.41. What are Endotherms?
Ans. Those animals which maintain
their body temperature by generating heat in their bodies are called
endotherms.
Q.42. What are Heterotherms?
Ans. Those animals which generate
heat in their bodies to keep their body temperature to wider range. E.g. Bats,
Humming Birds.
Q.43. How mammals control their body
temperature physiological means during cold environment?
Ans. Thermoregulation in cold temperature.
Physiological Mechanism
(a) Non-Shivering Thermogenesis
i. Erection of Hairs:
During cold weather hair of bodies becomes erect due the contraction in erector
pilli muscles in skin. Vertical hair trap air near to skin which reduces heat
loses from skin.
ii. Subcutaneous Fact Acelmulation: Mammals live in colder regions of world have thick layer
of adipose tissues under their skin. These adipose tissues work as insulator
and reduce head loss.
iii. Reduction in Blood Flow Through Skin: In cold temperature, arteries and veins in skin become
narrow due to which blood circulation in skin decreases and heat loss is
reduced due to radiation.
(b) Shivering Thermogenesis
In colder weather brain starts
involuntary muscle movement called shivering which helps in generating heat to
increase the body temperature.
Q.44. How mammals regulate their body
temperature by behavioural means during cold environment?
Ans. Thermoregulation in Cold
Temperature
Behavioural Mechanism.
In colder weather animals move
towards warm places to maintain their body temperature.
Q.45. How mammals control their body
temperature by physiological means during hot environment?
Ans. Thermoregulation in Hot Temp
Physiological Mechanism
i. Lowering of Hair:
In hot weather animals lower their hair to reduce insulating effect.
ii. Increase in Blood Flow Towards Skin: Arteries and veins of skin become dilate due to which
blood circulation increases in skin and heat loss occurs due to radiation.
iii. Sweating:
In summer sweet glands secrete sweat, which when evaporates body looses heat.
Q.46. How mammals regulate their body
temperature by behavioural means during hot environment?
Ans. Behavioral Mechanims:
Animal during summer move towards
colder region to maintain their body temperature.
Q.48. How hypothalamus act as a Thermostate
for the body.
Ans. Role of Brain in Temperature
Regulation
Hypothalamus is the part of brain
which regulates the body temperature. In this way this is called the most at of
body. Hypothalamus receives messages from thermo receptor present in the skin.
When any change in the temperature is detected by the hypothalamus,
instructions are sent to the particular organ to bring the body temperature
back to normal. For example in summer body promotes heat loss by evaporation of
sweat from skin. But during winter body generates heat by different mechanism.
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