by Karthik Gurumurthy
When you stand up, how does your blood get to your brain instead of pulling inside your feet? The heart pumps blood through your whole body. And it never stops pumping. If it did, your cells would stop receiving the materials they need to survive.
Your heart is nestled between your lungs inside your rib cage. It has four chambers, or spaces, where the blood collects-two on the right and two on the left. The upper chambers on each side are called atria and the lower chambers are called ventricles. Blood enters the heart through the atria and leaves the heart through the ventricles. The thick muscular walls of the chambers contract to make the heart “pump.”
Blood always flows through your heart and your body in one direction.That way it can get rid of waste and receive a fresh supply of nutrients and oxygen before passing by the cells again. To prevent the blood from moving backward, at the entrance of each chamber, the heart has a series of valves, which act like automatic doors. They close once blood enters a chamber, thereby forcing it to exit in the proper direction.
Blood is pumped through the heart twice as it circulates through the body-once through the right side and once through the left. A layer of tissue separates the two sides of the heart so that the blood in each side never mixes.
Blood returning from the body first enters the right atrium where it passes into the right ventricle. It is pumped out of the right ventricle and sent straight to the lungs, where it gets ride of the carbon dioxide and picks up a fresh supply of oxygen. From the lungs, the oxygen-rich blood enters the left atrium where it is sent to the left ventricle.
From the left ventricle, the blood begins its circuit through the body’s blood vessels again.
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