Tag: excretion and osmoregulation

Questions Related to excretion and osmoregulation

Juxtaglomerular cells secrete A when there is a fall in B concentration. Choose the correct pair labelled as A and B.

zoology excretion and osmoregulation regulation of urine formation properties of urine and regulation of urine formation coordination in human beings- chemical control

  1. A : Renin, B : Chloride

  2. A : Carbonic anhydrase, B : Sodium

  3. A : ATPase, B : Potassium

  4. A : Renin, B : Sodium chloride

Show answer
Correct Option: D
Explanation:

Juxtaglomerular cells are the specialized smooth muscle cells present in the walls of the afferent arterioles that go to the glomerulus. Their function is to produce an enzyme called renin when the osmolarity of blood changes. Renin converts angiotensin secreted by the liver into angiotensin$I$. This is later converted into angiotensin$II$ by an enzyme released by lungs. Angiotensin$II$ acts on adrenal glands to stimulate the release of aldosterone. Aldosterone helps in reabsorption of na+ and water from distal convoluted tubule and the concentration of Na$^+$ ions decreases in the filtrate. 

So juxtaglomerular cells secrete renin when then is fall in sodium chloride  concentration
So, the correct option is D.

A fall in glomerular filtration rate (GFR) activates 

zoology excretion and osmoregulation regulation of urine formation properties of urine and regulation of urine formation coordination in human beings- chemical control

  1. Juxtaglomerular cells to release renin

  2. Adrenal cortex to release aldosterone

  3. Adrenal medulla to release adrenaline

  4. Posterior pituitary to release vasopressin

Show answer
Correct Option: A
Explanation:

A fall in GFR can stimulate the JG cells to release renin which can stimulate the glomerular blood flow and thereby the GFR comes back to normal.

If the concentration of urine  decreases .......... hormone will be released.

zoology excretion and osmoregulation regulation of urine formation properties of urine and regulation of urine formation coordination in human beings- chemical control

  1. LH

  2. FSH

  3. ADH

  4. Oxytocin

Show answer
Correct Option: C
Explanation:

A) LH is Luteinising Hormone which is not involved in the concentration of urine.

B) FSH is Follicle Stimulating Hormone which is not involved in the concentration of urine.
C) ADH (Anti Diuretic Hormone) is responsible for retaining water from the urine and preventing diuresis (dilute urine).
D) Oxytocin is the maternal hormone produced during child birth which is not involved in the concentration of urine.
So the correct answer is 'ADH'.

The stimulants present in tea, cocoa and cola drink

zoology excretion and osmoregulation regulation of urine formation properties of urine and regulation of urine formation coordination in human beings- chemical control

  1. Cocaine

  2. Tannin

  3. Opium

  4. Caffeine

Show answer
Correct Option: D
Explanation:

Caffeine is a central nervous system stimulant of the methylxanthine class of psychoactive drugs. It is the most mildest stimulant and is most widely consumed psychoactive drug. It is present in coffee, tea and cola drinks.
Therefore, the correct answer is option D.

Absorption of ${ H } _{ 2 }O$ in DCT is controlled by

zoology excretion and osmoregulation regulation of urine formation properties of urine and regulation of urine formation coordination in human beings- chemical control

  1. ADH

  2. ACTH

  3. LH

  4. Oxytocin

Show answer
Correct Option: A
Explanation:

The water reabsorption in the distal part of the nephron is in accordance with the body's state of hydration, under the influence of ADH and is termed as 'facultative reabsorption of water'.  ADH is secreted in the hypothalamus of brain and released into blood stream from the pituitary gland. The collecting ducts become more permeable to water due to the effect of ADH, so more water is reabsorbed by osmosis and no expenditure of ATP energy is required. The release of ADH is triggered when osmoreceptors in the hypothalamus detect an increase in osmolarity of the blood above a set point of ${300 mosm L^{-1}}$. In this situation the osmoreceptors cells also promotes thirst. Drinking reduces the osmolarity of the blood, which inhibits the secretion of ADH.

Renin is secreted by

zoology excretion and osmoregulation regulation of urine formation properties of urine and regulation of urine formation coordination in human beings- chemical control

  1. Cortex

  2. Medulla

  3. Juxta glomerular cells

  4. Podocytes

Show answer
Correct Option: C
Explanation:

Juxtaglomerular cells are specialized smooth muscle cells of glomerular arterioles. They synthesize, store and secrete the enzyme renin. It plays a critical role in the renin angiotensin system and thus in renal autoregulation of the kidney.