A Level Biology Practice Exam

What is vasodilation?

1. An increase in heart rate during exercise

2. A decrease in blood flow to major organs

3. An increase in the diameter of the lumen of arterioles allowing increased blood flow to specific regions of the body

4. A process involving the narrowing of blood vessels

The correct answer is: An increase in the diameter of the lumen of arterioles allowing increased blood flow to specific regions of the body

Vasodilation refers to the physiological process in which blood vessels, specifically arterioles, widen or increase in diameter. This widening of the lumen allows for increased blood flow to various regions of the body. The relaxation of the smooth muscle fibers in the vessel walls causes this effect, which, in turn, enhances oxygen and nutrient delivery to tissues that require it most, especially during situations such as physical exercise or when the body needs to dissipate heat. This process is vital for regulating blood pressure and ensuring adequate blood supply based on the varying demands of different bodily functions. For example, during exercise, vasodilation helps to direct more blood towards the active muscles while regulating overall body temperature. Therefore, the correct understanding of vasodilation focuses on its role in increasing blood flow, which is why the answer that describes an increase in the diameter of arterioles allowing for this enhanced blood flow is accurate.