Capillaries are the smallest blood vessels in the body. In the circulatory system, capillaries are asked to identify which option best completes the statement.

Capillaries are the smallest blood vessels in the body. In the circulatory system, capillaries are asked to identify which option best completes the statement.

• A. Tiniest blood vessels in the body
• B. Largest arteries
• C. Muscular vessels that regulate blood pressure
• D. Lymphatic vessels

Answer: (A)

Capillaries are the tiniest blood vessels in the body, and their very small diameter plus walls that are just one cell thick enable rapid diffusion of oxygen, carbon dioxide, nutrients, and wastes between blood and tissues. This exchange capability is what makes capillaries the essential link between the arterial and venous sides of the circulation. Among the options, the phrase that capillaries are the tiniest blood vessels best completes the statement. The other choices describe arteries (largest vessels), muscular vessels that regulate blood pressure, and vessels of the lymphatic system, which are not part of the circulatory capillary network.

Capillaries are the tiniest blood vessels in the body, and their very small diameter plus walls that are just one cell thick enable rapid diffusion of oxygen, carbon dioxide, nutrients, and wastes between blood and tissues. This exchange capability is what makes capillaries the essential link between the arterial and venous sides of the circulation. Among the options, the phrase that capillaries are the tiniest blood vessels best completes the statement. The other choices describe arteries (largest vessels), muscular vessels that regulate blood pressure, and vessels of the lymphatic system, which are not part of the circulatory capillary network.