Questions: Choose all that are features of lymphatic vessels. They resist moderate to high pressure Smooth muscle is present in the vessel wall Valves are present A tunica interna is present They have thick walls

The features of lymphatic vessels are:

• Smooth muscle is present in the vessel wall
• Valves are present
• A tunica interna is present

Explanation for each option:

1. They resist moderate to high pressure: Incorrect. Lymphatic vessels are low-pressure vessels. They do not resist moderate to high pressure like arteries do.

2. Smooth muscle is present in the vessel wall: Correct. Lymphatic vessels have smooth muscle in their walls, which helps in the propulsion of lymph.

3. Valves are present: Correct. Lymphatic vessels contain valves that prevent the backflow of lymph, ensuring it moves in one direction towards the heart.

4. A tunica interna is present: Correct. Lymphatic vessels have a tunica interna (intima), which is the innermost layer of the vessel wall.

5. They have thick walls: Incorrect. Lymphatic vessels have relatively thin walls compared to arteries and veins.

Summary: The features of lymphatic vessels include the presence of smooth muscle in the vessel wall, valves, and a tunica interna. They do not resist moderate to high pressure and do not have thick walls.