Question

Give reason for the following
Certain useful products like glucose, salt, etc, are filtered but not excreted by ultrafiltration.

Answer 1

Ultrafiltration:

1. Ultrafiltration is the first step in the urine production process.
2. It incorporates blood filtration in the glomerulus.
3. The blood travels through the glomerulus at high pressure during ultrafiltration because the efferent (outgoing) arteriole is smaller than the afferent (incoming) arteriole, this occurs.
4. The liquid fraction of the blood is filtered out of the glomerulus and passes into the Bowman's capsule before entering the renal tubule due to the high pressure.

Filtration:

1. The glomerular filtrate, also known as primary urine, is the fluid that enters the renal tubule. It has a hypotonic effect on the urine, which is expelled.
2. Glomerular Filtration Rate or GFR is the amount of filtrate produced by the kidneys per minute.
3. Glucose, salt, and other substances are reabsorbed in the proximal tubules of the kidneys and hence are not filtered.