Question 17

Lymphatic capillaries are small, clear vessels responsible for draining excess interstitial fluid.

Lymphatic capillaries are specialized vessels that collect and drain excess interstitial fluid from tissues, which is crucial for maintaining fluid balance in the body. They are specifically designed to absorb this fluid that is not reabsorbed by blood capillaries, thereby preventing edema.

A) venules

Venules are small blood vessels that collect blood from capillaries and transport it back to larger veins. They do not play a role in draining interstitial fluid; instead, they are involved in the return of blood to the circulatory system, making them incorrect in the context of this question.

B) immune capillaries

The term "immune capillaries" is not commonly used in anatomical terminology and does not refer to a recognized type of vessel responsible for draining interstitial fluid. This option is misleading and thus does not accurately describe the vessels in question.

C) arterioles

Arterioles are small blood vessels that lead from arteries to capillaries and are primarily involved in regulating blood flow and pressure. They do not have the function of draining interstitial fluid, which makes this option incorrect.

D) lymphatic capillaries

Lymphatic capillaries are the correct answer as they are specifically designed to collect excess interstitial fluid that cannot be reabsorbed by blood capillaries. They play a vital role in the lymphatic system, contributing to fluid balance and immune function.

Conclusion

Lymphatic capillaries are essential for draining excess interstitial fluid, distinguishing them from other vessels such as venules, arterioles, and the incorrectly termed immune capillaries. This function is critical for preventing fluid accumulation in tissues, reinforcing why option D is the definitive correct answer while all other options fail to meet the criteria set by the question.