Where do gases exchange?

Answer 1

The pathway of the circulatory system varies based on different species. The mammalian cardiovascular system begins with the pulmonary circuit. The right ventricle pumps blood to the lungs via the pulmonary arteries. As the blood flows through capillary beds in the lungs, it adds oxygen and subtracts carbon dioxide. Oxygen-rich blood comes from the lungs via the pulmonary veins to the left atrium of the heart. Next the oxygen-rich blood flows into the left ventricle as the ventricle opens and the atrium closes. The left ventricle pumps the oxygen-rich blood out of the body tissues through the systemic circuit. Blood leaves the left ventricle through the aorta, which passes blood to arteries leading throughout the body. The first branches from the aorta are the coronary arteries which provide blood that the heart muscle needs. Then come branches leading to capillary beds in the forelimbs. The aorta continues, supplying oxygen-rich blood to arteries leading to arterioles and capillary beds in the abdominal organs and legs. Inside the capillaries, oxygen and carbon dioxide diffuse along their concentration gradients with oxygen being moved from the blood to the tissues. Carbon dioxide produced by cellular respiration diffuses into the bloodstream. Capillaries join again, forming venules, which give blood to veins. Oxygen-poor blood from the head, neck, and forelimbs is guided into a large vein called the anterior vena cava. Another large vein called the posterior vena cava drains blood from the chest and back legs. The two venae cavae empty their blood into the right atrium and the oxygen-poor blood flows into the right ventricle.