Which of the following statements about the vessels in the body are correct?

Question

Venules are connected directly to arteries.

Endothelium, tunica media and tunica externa are found in both veins and arteries.

All arteries contain valves to prevent the back-flow of blood.

They make up an open circulatory system.

Answer 1

Let's evaluate each statement regarding the vessels in the body:

1. Venules are connected directly to arteries.

   • Incorrect. Venules are small blood vessels that drain blood from capillaries and lead to veins. They do not connect directly to arteries; instead, they connect to capillaries.

2. Endothelium, tunica media and tunica externa are found in both veins and arteries.

   • Correct. Both veins and arteries have three main layers: the endothelium (inner layer), the tunica media (middle muscular layer), and the tunica externa (outer layer).

3. All arteries contain valves to prevent the back-flow of blood.

   • Incorrect. While veins contain valves to prevent the back-flow of blood, most arteries do not have valves. The high pressure of blood flow in arteries typically prevents backflow.

4. They make up an open circulatory system.

   • Incorrect. Humans and most vertebrates have a closed circulatory system, where blood circulates within vessels. An open circulatory system is found in some invertebrates, where blood (hemolymph) bathes the organs directly rather than being confined to blood vessels.

In summary, the only correct statement is: Endothelium, tunica media and tunica externa are found in both veins and arteries.