Question

Observe the chart depicting the structure of a nephron.
(i) Mention the structures A to F
(ii) Explain the main function of a nephron.

Answer 1

A. Glomeru­lus - Blood enters from afferent arteriole and leave through efferent arteriole.

B. Bowman’s capsule

C. Proximal Convoluted Tubule

D. Loop of Henle

E. Distal Convoluted Tubule

F. The Juxtaglomerular Apparatus (JGA)

The basic function of the nephron is to filter blood and remove waste substances while retaining essential substances for various biochemical processes. In the process, the nephron can also influence the pH (acid-base balance) of the blood, regulate blood pressure, maintain the blood volume and control the level of electrolytes in the body fluids.

The functions of the nephron can be discussed with regard to each part :

• Bowman’s capsule

Collects the incoming fluid from the glomerular capillaries.

• Proximal tubule

Sodium, chloride, water, glucose and amino acids are reabsorbed (removed from the tubules).

Organic acids and bases like bile salts, oxalate and urate are secreted into the proximal tubule.

• Loop of Henle

Water is reabsorbed mainly in the descending limb and thin segment of the ascending limb.

Sodium, calcium, chloride, magnesium and potassium are actively reabsorbed in the thick segment of the ascending limb.

• Distal tubule

Controls the blood flow through the glomerular capillaries and glomerular filtration of the nephron to which it belongs.

Sodium, potassium and chloride reabsorption.

• Collecting tubule

Sodium, potassium and chloride reabsorption.

Hydrogen ion secretion.