What are venules?

Venules are small veins that function as the connection between capillaries and larger veins within the circulatory system. They collect deoxygenated blood from capillary beds, where gas and nutrient exchange occurs, and channel it towards the larger veins, which then return the blood to the heart. This structural role is essential for maintaining proper blood flow and pressure within the circulatory system.

Understanding venules is important because they are crucial in regulating blood flow and contributing to the overall function of the cardiovascular system. They also play a role in inflammation and play a part in the immune response, as they can become more permeable to allow immune cells to exit the bloodstream and reach sites of injury or infection.

The other options do not accurately describe venules. Small arteries refer to a different type of blood vessel that carries oxygenated blood away from the heart. Major blood vessels are larger vessels, such as arteries and veins, that serve different roles than venules. Capillaries without exchange abilities would misrepresent the function of capillaries, which are specifically designed for the exchange of gases, nutrients, and waste products.