the heart to function properly, the four chambers must beat in
an organized manner. The four heart chambers fill with and pump
blood. The right and left atria pump blood to the right and left
four heart valves are: 1. the tricuspid valve, located between
the right atrium and right ventricle; 2. the pulmonary or pulmonic
valve, between the right ventricle and the pulmonary artery; 3.
the mitral valve, between the left atrium and left ventricle;
and 4. the aortic valve, between the left ventricle and the aorta.
Each valve has a set of flaps (also called leaflets or cusps).
The mitral valve has two flaps; the others have three. Under normal
conditions, the valves permit blood to flow in only one direction.
Blood flow occurs only when there's a difference in pressure across
the valves that causes them to open.
Blood returning to the heart from the body (venous blood that
has already had oxygen taken from it) enters the right atrium.
Blood flows and is pumped from the right atrium across the open
tricuspid valve into the right ventricle.
the right ventricle starts to contract the tricuspid valve closes
(blood can only be pumped forward) the pulmonic valve opens and
blood pumped into the pulmonary arteries. These arteries carry
blood to the lungs to be oxygenated.
blood is returned to the heart by pulmonary veins. This oxygenated
blood enters the left atrium. Blood from the left atrium flows
across an open mitral valve to enter the left ventricle. As the
left ventricle starts to contract the mitral valve closes and
the aortic valve opens as blood is pumped across it into the aorta.The
aorta and arteries that branch from it carry blood to the entire
body. The left ventricle is the largest and most forcefully contracting
chamber of the heart. It must pump oxygen rich blood to the whole
heartbeat cycle consists of two components: diastole and systole
Diastole occurs when the heart is relaxed and not contracting.
During diastole blood fills each of the atria and begins filling
occurs when electrical impulse traveling down specialized conducting
fibers trigger the heart to contract. The left and right atria
contract at nearly the same time pumping remaining blood into
the left and right ventricle. Systole continues as the right
and left ventricle contract, pumping blood to the lungs and
body, several tenths of a second after the right and left atria
and diastole continuously alternate as long as the heart continues