Exchange of gases and waste materials occurs by diffusion across the walls of the

Question

A. veins.

B. lymphatic vessels.

C. capillaries.

D. arteries.

Answer 1

C. capillaries.

Answer 2

capillaries

Answer 3

C. Capillaries

Arteries take the blood away from the heart to its specific destination (brain, toe, arm...etc..) where it then enters into the capillaries. When it reaches the capillaries, all the gases and waste materials are exchanged. After diffusion has taken place, the blood enters back into the vein for its return back to the heart. Think of the capillary as a "U-turn" where the blood drops off all of its nutrients and picks up all the "trash" before it takes the vein "highway" back to the heart.

From here it goes back to the heart and the process starts all over again. It takes about 60 seconds for blood to make one trip around the body.