Question

The constituents of glomerular filtrate are
(a) Water, proteins, urea, uric acid, and glucose
(b) Water, fatty acids, amino acids, vitamins, and urea
(c) Water and organic substances like urea, glucose, amino acid, and ammonia
(d) Water, fat, protein, and urea

Answer 1

Hint: The glomerular filtrate and the blood plasma are similar in their constituents except that glomerular filtrate does not contain plasma proteins and fats. The glomerular filtrate is not a concentrated solution of the waste products, rather is just a filtrate lacking red blood cells and plasma proteins.

Complete answer:
The glomerular filtrate contains a large amount of water and other dissolved substances such as urea, ammonia, amino acids, glucose, and various ions such as sodium, potassium.

The following are the steps for the production of glomerular filtrate:
1. The initial step in the formation of urine is the filtration of blood, which is carried out by the glomerulus known as glomerular filtration.
2. Then, the glomerular capillary blood pressure causes filtration of blood through 3 layers, i.e., via the endothelium of glomerular capillary blood vessels, the second layer of a basement membrane, and the third layer of the epithelium of Bowman's capsule.
3. The epithelial cells of Bowman's capsule are known as podocytes that are arranged in such a manner that they leave some minute spaces called filtration slits.
4. The blood is filtered so finely through these membranes, that almost all the constituents of the plasma except the proteins and blood cells pass into the lumen of the Bowman's capsule. Therefore, this process is considered as ultrafiltration.
So, the correct answer is ‘water and organic substances like urea, glucose, amino acid, and ammonia’.

Note:
- In addition to Bowman’s unit, kidneys also consist of special capillary tubes called the peritubular capillaries that are tiny blood vessels that run parallel to and surround the proximal and distal tubules of the nephron. The loop of Henle is an important unit for countercurrent exchange that concentrates the urine.
- The basement membrane is also made up of three layers and is fused to the endothelial layer. It prevents the plasma proteins from being filtered out of the bloodstream.