A small rise in the body terperature of humans is correctly by : (i) Sweating (ii) Dilating the skin arteries (iii) Constricted the skin arteries (iv) Inreased tension of muscles in the skin

Options

A. I only
B. ii only
C. I and ii
D. iii and iv

Answer

To solve the question regarding how a small rise in body temperature in humans is corrected, we can analyze each option provided:

1. **Understanding Thermoregulation**: The human body maintains a stable internal temperature through a process called thermoregulation, which is primarily controlled by the hypothalamus in the brain. When the body temperature rises, the hypothalamus activates mechanisms to cool the body down.

2. **Analyzing the Options**:
- **(i) Sweating**: When the body temperature increases, the sweat glands produce more sweat. As the sweat evaporates from the skin surface, it cools the body down. This is a correct response to a rise in body temperature.

- **(ii) Dilating the skin arteries**: The blood vessels in the skin dilate (widen) when the body temperature rises. This process, known as vasodilation, allows more blood to flow to the skin, facilitating heat loss to the environment. This is also a correct response.

- **(iii) Constricted the skin arteries**: When the body temperature decreases, the blood vessels constrict (narrow) to conserve heat. This process, known as vasoconstriction, is not a response to a rise in body temperature, making this option incorrect.

- **(iv) Increased tension of muscles in the skin**: Increased tension in the skin muscles (like the erector pili muscles) occurs primarily when the body is cold, as they help to trap heat. This is also an incorrect response to a rise in body temperature.

3. **Conclusion**: Based on the analysis, the correct responses to a small rise in body temperature are:
- (i) Sweating
- (ii) Dilating the skin arteries

Thus, the correct answer is **(i) and (ii)**.