Question

Explain in your own words with suitable examples. 

How does excretion occur in human beings?

Answer 1

The human excretory system includes the kidneys, along with the ureters, bladder, and urethra. Urine is produced by the kidneys by separating waste materials from the blood and discarding excess and unnecessary substances.

Process of urine preparation:

1. In the kidneys, urine is produced after the filtration process of blood through the nephrons.
2. In Bowman's capsule of the nephron, the glomerulus is a plexus of blood cells. Urea produced by the liver comes into the blood. When this urea-rich blood reaches the glomerulus, it is filtered by the blood cells of the glomerulus.
3. The selective membrane of Bowman's capsule allows water molecules and small molecules of other substances to pass through the pore.
4. The fluid present in Bowman's capsule later reaches the nephron tubule. Water and appropriate molecules are mixed back into the blood in different parts of the nephron tubule.
5. Urine is prepared from all the constituent substances unnecessary to the body.
6. The produced urine is stored in the bladder through the ureters.
7. There is voluntary control over passing urine, hence when desired, it is expelled through the urinary tract. ​