61. 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:
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

Introduction:

Thermoregulation is the process by which the body maintains its core temperature within a narrow, optimal range. The hypothalamus, a small but vital part of the brain, plays a central role in regulating body temperature. In response to rising temperatures, the hypothalamus triggers specific physiological responses, including sweating and blood vessel dilation, to dissipate excess heat. Let’s take a closer look at these mechanisms and evaluate the claims about the role of the hypothalamus in temperature regulation.

The Role of the Preoptic Anterior Hypothalamic Area:

The preoptic anterior hypothalamic area is a critical region of the brain that regulates thermoregulation. When the body becomes too warm, this area of the hypothalamus detects the temperature change and initiates responses aimed at cooling the body.

Two key responses include:

• Sweating: Sweat glands are activated to release moisture onto the skin. As sweat evaporates, it cools the body.

• Blood Vessel Dilation: The blood vessels near the skin surface dilate, allowing more blood to flow through and increasing heat loss through the skin.

Assertion A: Heating the Preoptic Anterior Hypothalamic Area

Assertion A states: “Heating of preoptic anterior hypothalamic area of the brain caused profuse sweating and dilation of blood vessels of the skin.”
This statement is correct. When the hypothalamus detects that the body is too warm, it triggers mechanisms like sweating and blood vessel dilation to facilitate heat loss and prevent overheating. These processes are key to regulating body temperature and ensuring the body maintains its optimal thermal environment.

Reason R: The Purpose of Sweating and Blood Vessel Dilation

Reason R states: “The above (in A) is to absorb more heat into the body and throw out waste from the body.”
This statement is incorrect. While sweating and blood vessel dilation are mechanisms for cooling the body, they do not serve the purpose of absorbing heat into the body. Rather, they help remove excess heat and cool the body. Additionally, sweating does not primarily function to expel waste products; while sweat contains small amounts of waste like salts, its primary role is temperature regulation.

Analysis of the Statements:

• Assertion A: Correct. The hypothalamus regulates body temperature by initiating sweating and blood vessel dilation when the body is overheated.

• Reason R: Incorrect. Sweating and blood vessel dilation are not meant to absorb heat but to dissipate it, and sweating is not a significant means of waste removal.

Conclusion:

The correct answer is C. A is correct but R is incorrect. Assertion A accurately describes the physiological response to heat, while Reason R misrepresents the purpose of these mechanisms.

Answer:

C. A is correct but R is incorrect