When outside temperature is high, the blood vessel gets dilated. This phenomenon is known as :

Options

A. Vasodilation
B. Vasoconstriction
C. Peristalsis
D. Expiration

Answer

**Step-by-Step Text Solution:**

1. **Understanding Blood Vessel Behavior**: When the outside temperature is high, the body needs to regulate its internal temperature to maintain homeostasis. One of the ways the body does this is by adjusting the diameter of blood vessels.

2. **Vasodilation**: The process where blood vessels widen or dilate is known as vasodilation. This occurs to increase blood flow to the skin, allowing heat to dissipate more effectively.

3. **Physiological Response**: As blood vessels dilate, more blood reaches the surface of the skin, which helps to cool the body down through the process of heat loss.

4. **Terminology**: The phenomenon of blood vessels dilating in response to high external temperatures is specifically referred to as "vasodilation."

5. **Conclusion**: Therefore, when the outside temperature is high, the dilation of blood vessels is known as vasodilation.

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