Question

Give a biological reason for the following statement:

There is frequent urination in winter than in summer.

Answer 1

Urination is more frequent in winter than in summer:

1. Humans are homoeothermic animals (Warm-blooded).
2. In human beings, uniform body temperature is maintained by its physiological system.
3. During winter body tries to keep itself warm. For that reason, blood vessels become constricted.
4. Because of the constricted blood vessels, the blood pressure is increased.
5. The increased blood pressure gives negative feedback to the posterior pituitary to reduce ADH (antidiuretic hormone) secretion.
6. Hyposecretion of ADH decreases the reabsorption of water in the distal convoluted tubule (DCT) and collecting duct of nephrons. For that reason, a large volume of hypotonic urine is produced.

Hence, urination is more frequent in winter than the summer.