Question

Discuss the role of the renal tubules in the urinary system.

Answer 1

1. Renal tubules are the tubular parts of nephrons, the structural and functional units of the kidneys.
2. Each renal tubule consists of the proximal convoluted tubule (PCT), loop of Henle and distal convoluted tubule (DCT). The DCTs of several nephrons open into collecting ducts.
3. The glomerular filtrate formed in the Bowman's capsule enters the renal tubule.
4. The renal tubules selectively reabsorb useful substances such as glucose, amino acids, salts and water into the blood. Nearly 99% of the glomerular filtrate is reabsorbed.
5. The loop of Henle and collecting ducts help in the reabsorption of water and thereby concentrate the urine.
6. The tubules also secrete unwanted substances such as hydrogen ions, potassium ions, ammonia, drugs, toxins and excess urea into the filtrate.
7. Through reabsorption and tubular secretion, the renal tubules maintain the proper water, salt and osmotic balance of the blood.
8. The remaining filtrate becomes urine and passes through the collecting ducts into the renal pelvis and then into the ureter.