PATHOLOGY

Detailed explanation-1: -veins-these return blood to the heart. capillaries-these are tiny vessels that connect arteries and veins. Their thin walls allow blood to come into close contact with tissues to exchange oxygen, carbon dioxide, nutrients and waste products.

Detailed explanation-2: -Capillaries are small, thin blood vessels that connect the arteries and the veins. Their thin walls allow oxygen, nutrients, carbon dioxide and waste products to pass to and from the tissue cells.

Detailed explanation-3: -The cells need oxygen for metabolism, which creates carbon dioxide as a waste product. The carbon dioxide is absorbed from the cells by the blood plasma (some of it binds to hemoglobin too) and is transported back to the lungs in the bloodstream. There it leaves the body when we breathe out.

Detailed explanation-4: -Veins. Veins have one-way valves instead of muscles, to stop blood from running back the wrong way. Generally, veins carry deoxygenated blood from the body to the heart, where it can be sent to the lungs. The exception is the network of pulmonary veins, which take oxygenated blood from the lungs to the heart.