Countercurrent Multiplication

Q. In the kidneys, the __(i)__ and the __(ii)__ mechanisms occur. The first takes place in a region of the nephron called __(iii)__; the second occurs in a region of the peritubular capillary bed called the ___(iv)___

1. i-Counter-current multiplier, ii-Counter-current exchanger, iii-Henle's loop, iv-Vasa recta.

2. i-Counter-current exchanger, ii-Counter-current multiplier, iii-Henle's loop, iv-Vasa recta.

3. i-Counter-current multiplier, ii-Counter-current exchanger, iii-Vasa recta, iv-Henle's loop.

4. i-Counter-current exchanger, ii-Counter-current multiplier, iii-Vasa recta, iv-Henle's loop.

Q. The ascending limb of Henle and the early distal tubule are __(i)__ to water. These regions actively transport __(ii)__ out of the filtrate and into the surroundings.

1. Impermeable to water and Sodium chloride (NaCl)
2. Impermeable to water and Potassium
3. Permeable to water and Chloride
4. Permeable to water and Potassium

Q. In the loop of Henle, urine is most concentrated in ______.

1. Area between ascending limb and distal convoluted tubule
2. Descending limb
3. Thick ascending limb
4. Hairpin bend between descending and ascending limbs

Q. The ascending limb of the loop of Henle, transports solutes out and the descending loop transports water out to maintain a gradient, this is called .

1. flow of fluid
2. single effect
3. countercurrent
4. flow of filtrate

Q. Assertion :The renal fluid becomes increasing concentrated when it flows down in the descending limb of loop of Henle towards inner medulla, but its concentration decreases in the ascending limb when it flows towards the cortex. Reason: The descending limb of the loop of Henle water is reabsorbed, the ascending limb is impermeable to water but salt are absorbed.

1. Both (A) and (R) are true (R) is the correct explanation to (A)
2. Both (A) and (R) are true (R) is not the correct explanation to (A)
3. (A) is true, but (R) is false
4. (A) is false, but (R) is true

Q. The secretion of K+ by the distal tubule will be decreased by

1. Metabolic alkalosis
2. A high K${}^{+}$ diet
3. Hyperaldosteronism
4. Spironolactone administration

Q.

The principal buffer in interstitial fluid is

1. Carbonic acid
2. Hb
3. Compounds containing histidine
4. Phosphate

Q.

An increase in the concentration of plasma potassium causes an increase in

1. Release of renin
2. Secretion of aldosterone
3. Secretion of ADH
4. Release of natriuretic hormone

Q.

ADH (vasopressin) secretion is increased by

1. Alcohol
2. Carbamazepine
3. Extracellular fluid volume
4. Angiotensin I

Q. What is the correct option for the maintenance of concentration of urine?

1. Counter-current produced in two limbs of Henle's loop
2. Counter-current produced in two limbs of vasa recta
3. Ascending limb of Henle's loop
4. Counter-current produced by Henle's loop and vasa recta