OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

What does vasoconstriction primarily affect in the body?

1. Blood flow near the surface of the skin

2. Heart rate and rhythm

3. Muscle contraction and relaxation

4. Temperature regulation of the body

The correct answer is: Blood flow near the surface of the skin

Vasoconstriction primarily affects blood flow near the surface of the skin by narrowing the blood vessels, which decreases the diameter of the blood vessels in response to various signals, such as cold temperatures or stress. This process reduces the amount of blood that flows close to the skin, which can help conserve body heat in cold conditions by minimizing heat loss to the environment. By constricting blood vessels, the body can redirect blood flow to vital organs, thereby maintaining core temperature and protecting against hypothermia. While heart rate and rhythm, muscle contraction and relaxation, and temperature regulation are all important physiological processes, they are not the direct results of vasoconstriction. Instead, vasoconstriction serves more specifically to regulate blood flow and contribute to temperature control indirectly by managing where blood is distributed within the body.