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NEPHRON

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NEPHRON

6
Q. 1 In humans, the percentage of nephrons that having long loops is:
 A 5%
 B

15%
 C

35%
 D

65%
Q. 2

Each kidney contains about — nephrons ‑

 A

One million
 B

Two million
 C

Four million
 D

5 million
Q. 3

Juxtamedullary nephrons in kidney are what percentage of total nephrons

 A

15
 B

50
 C

70
 D

90
Q. 4

Which of the following does NOT form a filtration barrier in nephrons:

 A

Podocytes
 B

Mesangium
 C

Endothelial cell
 D

Basement membrane
Q. 5

In the presence of vasopressin the greatest fraction of filtered water is re-absorbed which part of the nephron:

 A

Proximal tubule
 B

Distal tubule
 C

Loop of Henle
 D

Loop of Henle
Q. 6

Several hormones regulate the tubular reabsorption of water and electrolytes at different sites in the nephron. Which of the following combination is correct?

 A

Angiotensin in distal tubule
 B

Aldosterone in collecting ducts
 C

ADH in proximal tubule
 D

ANP in loop of Henle
Q. 1

In humans, the percentage of nephrons that having long loops is:

 A

5%
 B

15%
 C

35%
 D

65%
Ans. B
Explanation:
The convoluted proximal tubule straightens and the next portion of each nephron is the loop of Henle. The nephrons with glomeruli in the outer portions of the renal cortex have short loops of Henle (cortical nephrons), whereas those with glomeruli in the juxtamedullary region of the cortex (juxtamedullary nephrons) have long loops extending down into the medullary pyramids. In humans, only 15% of the nephrons have long loops.
 
Ref: Barrett K.E., Barman S.M., Boitano S., Brooks H.L. (2012). Chapter 37. Renal Function & Micturition. In K.E. Barrett, S.M. Barman, S. Boitano, H.L. Brooks (Eds), Ganong’s Review of Medical Physiology, 24e.

 

Q. 2

Each kidney contains about — nephrons ‑

 A

One million
 B

Two million
 C

Four million
 D

5 million
Ans.
A
Explanation:

A i.e., One million

Q. 3

Juxtamedullary nephrons in kidney are what percentage of total nephrons

 A

15
 B

50
 C

70
 D

90
Ans.
A
Explanation:

A i.e. 15%

Q. 4

Which of the following does NOT form a filtration barrier in nephrons:

 A

Podocytes
 B

Mesangium
 C

Endothelial cell
 D

Basement membrane
Ans.
B
Explanation:

B i.e. Mesangium

Q. 5

In the presence of vasopressin the greatest fraction of filtered water is re-absorbed which part of the nephron:

 A

Proximal tubule
 B

Distal tubule
 C

Loop of Henle
 D

Loop of Henle
Ans.
A
Explanation:

A i.e. Proximal tubule

Vasopressing acts on the collecting ducts and enhances their permeability to water.

When vasopressing is absent

–      The collecting duct epithelium is relatively impermeable to water and only 2% of water is reabsorbed.

–      However by the time water reaches collecting duct, a maximum of 60-70% has already been re- absorbed in the proximal tubules.

 

% of water reabsorbed in

absence of vasopressin

% of water reabsorbed in

presence of vasopressin

Proximal tubule

60-70%Q

60-70%0

Loop of Henle

15%

15%

Distal tubule

5%

5%

Collecting duct

2%

10%Q

Thus the greatest fraction of filtered water (60-70%) is reabsorbed in proximal tubule irrespective of presence or absence of vasopressinQ.

Q. 6 Several hormones regulate the tubular reabsorption of water and electrolytes at different sites in the nephron. Which of the following combination is correct?
 A Angiotensin in distal tubule
 B

Aldosterone in collecting ducts
 C

ADH in proximal tubule
 D

ANP in loop of Henle
Ans.
B
Explanation:

B i.e. Aldosterone in collecting duct

Hormones

Site of action in kidney

Angiotensin 11

Constricts afferent arterioles, helps to reduce GFR.

Aldosterone

Cortical collecting duct & Distal tubulesQ.

ADH

Medullary collecting ductQ.

ANP

Collecting duct.