# DBT JRF 2022 — Question 68

Exam: DBT JRF 2022 · Section: B · Topic: Physiology › Hypothalamus & Thermoregulation · Difficulty: Medium

## Question

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R Assertion A: Heating of preoptic anterior hypothalamic area of the brain caused profuse sweating and dilation of blood vessels of the skin. Reason R: The above (in A) is to absorb more heat into the body and throw out waste from the body. In the light of the above statements, choose the correct answer from the options given below:

## Options

- **A.** Both A and R are correct and R is the correct explanation of A
- **B.** Both A and R are correct but R is not the correct explanation of A
- **C.** A is correct but R is incorrect
- **D.** A is incorrect but R is correct

## Answer

Option C

## Explanation

Preoptic anterior hypothalamus and temperature regulation: The preoptic area of the anterior hypothalamus (POAH) is the body's thermostat: • When body temperature rises (or POAH is artificially heated): ✔ Triggers HEAT DISSIPATION responses: - Vasodilation of skin blood vessels (heat loss to environment) - Sweating (evaporative cooling) - Reduced metabolic heat production • When body temperature falls: ✔ Triggers HEAT CONSERVATION/GENERATION: - Vasoconstriction - Shivering thermogenesis - Non-shivering thermogenesis (brown adipose tissue) The INCORRECT explanation: Heating POAH causes sweating/vasodilation 'to absorb more heat from the environment' — this is wrong. Vasodilation LOSES heat to the environment, it does NOT absorb heat. Answer: Heating preoptic hypothalamus triggers heat dissipation (vasodilation, sweating) to LOSE heat, not absorb it.

Source: https://mypyqbuddy.com/questions/given-below-are-two-statements-one-is-labelled-6a104cd5920734408bc0c753