the blood within the capillary contain
Capillaries are where fluids, gasses, nutrients, and wastes are exchanged between the blood and body tissues by diffusion. Capillary walls contain small pores that allow certain substances to pass into and out of the blood vessel.lood Vessels. 1  Arteries-transport blood away from the heart. 2  Veins-transport blood to the heart. 3  Capillary-transport blood from arteries to the veins. 4  Sinusoids-vessels found in certain organs including the liver, spleen, and bone marrow.