Question

Describe how molecules are reabsorbed during reabsorption.

Answer 1

Selective reabsorption:

1. The second stage in the formation of urine is called selective or tubular reabsorption.
2. The renal tubules including the proximal convoluted tubule (PCT), Henle's loop, and distal convoluted tubule (DCT) are responsible for selective reabsorption.
3. Maximum reabsorption of water takes place in the PCT.

Mechanism:

1. The dilute solution that is resulted from the glomerular filtration enters the renal tubules.
2. Here, most of the materials present in the filtrate are reabsorbed by the renal tubules.
3. About 99% of the substances are reabsorbed in this step.
4. As the filtrate goes down the tubule, other substances such as salts, glucose, amino acids, etc. along with a little amount of water are reabsorbed by the tubules.
5. The particles are reabsorbed either by passive transport or active transport depending upon their nature.

The molecules are reabsorbed during reabsorption by the renal tubules present in the nephron either by passive or active transport.