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Transcript
Laura Spenceley
Task 2 - Cardiovascular
Anatomy & Physiology
Cardiovascular System – Blood Circulation
When a heart contracts and pushes blood into blood vessels, there is a specific path that the
blood follows through the body. The blood moves first through pulmonary circulation and
then carries on through systemic circulation. Pulmonary and systemic are the two circuits in
the two-circuit system of humans with our closed circulatory systems.
Pulmonary Circulation
Deoxygenated blood enters the right atrium via the superior vena cava and the inferior
vena cava. From the right atrium, the deoxygenated blood drains into the right
ventricle through the right atrioventricular valve. This valve is also referred to as
the tricuspid valve because it has three sections in its structure. When the ventricles
contract, the atrioventricular valve closes off the opening between the ventricle and the
atrium so that blood does not flow back up into the atrium. As the right ventricle contracts,
it forces the deoxygenated blood through the pulmonary semilunar valve and into
the pulmonary artery. It should be noted that this artery is the exception in the body as it
carries deoxygenated blood; all other arteries carry oxygenated blood. The semilunar valve
keeps blood from flowing back into the right ventricle once it is in the pulmonary artery. The
pulmonary artery carries the blood that is very low in oxygen to the lungs, where it becomes
oxygenated.
Systemic Circulation
Newly oxygenated blood returns to the heart via the pulmonary veins. It should be noted
that these are the only veins in the body that carry oxygenated blood; all other veins carry
deoxygenated blood. The pulmonary veins enter the left atrium. When the left atrium
relaxes, the oxygenated blood drains into the left ventricle through the left AV valve. This
valve is also called the bicuspid valve because it has only two sections in its structure. Next
the heart really compresses. As the left ventricle contracts, the oxygenated blood is pumped
into the main artery of the body, the Aorta. To get to the aorta, blood passes through
the aortic semilunar valve, which operates to keep blood from flowing from the aorta back
into the left ventricle. The aorta branches off into other arteries, which follow and branch
into smaller arterioles. The arterioles meet up with capillaries, which are the blood vessels
where oxygen is exchanged for carbon dioxide.