The Normal Heart
 The
normal heart is made up of a right and left side, each of which has an atrium and a
ventricle. The right atrium collects blood from the body, and allows the right ventricle
to eject it into the lungs to become oxygenated. In much the same way, the left atrium
collects blood passively from the lungs, allowing the left ventricle to eject the
oxygenated blood to the body.
Blood flows in one direction through the four chambers with the aid of the four heart
valves. These four heart valves are called the tricuspid, pulmonary, mitral, and aortic
valves.
Click here to see a more detailed diagram of the heart
 The Normal Circulation
Blood returns to the heart through two large veins, the superior and inferior vena cava
(1 and 2 in diagram). This 'blue', or deoxygenated, blood enters the right atrium' (3),
which empties blood through the tricuspid valve into the right ventricle (4). The right
ventricle ejects this oxygen-poor blood through the pulmonary valve and pulmonary artery
(5) into the lungs to become oxygenated. This oxygenated, or 'red' blood then returns by
the pulmonary veins (6) into the left atrium (7), through the mitral valve and into the
left ventricle (8). From there it is pumped through the aortic valve into the aorta (9),
which takes oxygen rich blood to the body.
Click here for more on the normal circulation |
