Answer
The two main circulations are the systemic circulation, and the pulmonary circulation
Work Step by Step
The two main circulatory routes are the systemic, and the pulmonary:
The systemic circulation begins in the left ventricle which pumps oxygenated blood out the heart by via the aorta. Blood in the systemic circulation goes all over the body; it supplies tissues with oxygen and nutrients, and removes carbon dioxide as well as metabolic wastes. Systemic circulation returns blood to the heart by venules and veins; these veins ultimately unite to form the superior and inferior venae cavae and deliver the blood to the right atrium-- which pumps it into the right ventricle.
Subdivisions of the systemic circulation are the coronary circulation-- which supplies the
myocardium; the cerebral circulation-- which supplies the brain; the hepatic-portal circulation
between the digestive organs and the liver, and the hypothalamo-hypophyseal portal system
between the hypothalamus and the anterior pituitary.
The pulmonary circulation carries deoxygenated blood from the right ventricle to the lungs via the
pulmonary arteries. In the lungs, blood unloads some carbon dioxide, and picks up some oxygen. The oxygenated blood returns to the heart's left atrium ( via the pulmonary veins ); thence it is pumped into the left ventricle.
