Question

lo 3.6. what is primary function of capillaries? absorbing nutrients from the small intestine into the bloodstream. producing red blood cells in the bone marrow. transporting carbon dioxide from the lungs to the bodys tissues. regulating blood pressure in the arteries and veins. exchanging of materials, like oxygen, between the blood and tissue cells.

Explanation:

Capillaries are the smallest blood vessels. Their thin walls allow for the exchange of substances like oxygen (from blood to cells) and carbon dioxide (from cells to blood) between blood and tissue cells.

• Absorbing nutrients from the small intestine into the bloodstream is mainly done by the intestinal villi's capillaries and lacteals, but it's a more specific function related to digestion rather than the primary general function of capillaries.
• Red blood cells are produced in the bone marrow, which is not a function of capillaries.
• Transporting carbon dioxide is mainly a function of red blood cells and larger blood vessels (in terms of moving it from tissues to lungs, not the other - way - around as stated in the option. Also, the main role of capillaries is exchange, not just transport).
• Regulating blood pressure is more related to the elasticity of arteries and the action of the cardiovascular system as a whole, not the primary function of capillaries.

Answer:

Exchanging of materials, like oxygen, between the blood and tissue cells.