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Unit 4 anatomy and physiology
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Unit 4- Anatomy and Physiology in Health andSocial Care
The Cardiovascular System
The heart is an organ that is a pump, its apart of the cardiovascular system. The role of
the heart within the cardiovascular is to pump the blood to the lungs and around the body
and it works to protect the body and remove waste. The heart beatis the speed in which the
heart beats on average the heart beats about 100,00 times a day and about 2.5 billion times
in a lifetime. It’s made up of cardiac musclewhich is involuntary muscle and cam contract
more powerfully when it’s stretched slightly. The job for the cardiac muscle is to pump blood
through the blood vessels in the body.
Structure of the heart and the cardiac cycle
The heart is a four-chambered muscular organ, it has three layers of tissue which
is epicardiumthat the outer layer, the myocardiumwhich is the middle layer and the inner
layer is the endocardium. The internal cavity of the heart is divided into four different
chambers they are the right and left atriumand the right and left ventricle. The two atria are
thin walled chambers that receive the blood from the veins. The two ventricles are the thicker
walled chambers that forcefully pump blood out of the heart. The right atrium receives the
deoxygenated blood from the systemic veins, the left atrium receives the oxygenated blood
from the pulmonary veins. Pumps need a set of valves to keep the fluid flowing in one
direction, the heart has two valves that keep the blood flowing in one direction. The valves
that are between the atria and the ventricles are called the atrioventricular valves. The right
atrioventricular valve is the tricuspid valveand the left atrioventricular is the bicuspid valve.
When the ventricles contract the atrioventricular valves clos so that the blood doesn’t flow
back into the atria. When the ventricles relax, semilunar valves close to prevent blood from
flowing back into the ventricles. The heart beatis the speed in which the heart beats on
average the heart beats about 100,00 times a day and about 2.5 billion times in a lifetime.
The sinoatrial nodeis one of the major elements of the cardiac conduction system and it’s
the system that controls the heart rate. The sinoatrial node is the hearts pacemaker and it
consist of a cluster of cells that are located in the upper of the wall of the right atrium. The
electrical impulses are generated there, they are conducted to the ventricles through the
AV node. The atrioventricular nodesare the nodes that control the heart rate and they serve
an electrical relay station, which slows the electrical current which is sent by the SA nodes.
this being before the signal is permitted to pass through to the ventricles, this then allows
the atria to have time to fully contract before the ventricles are stimulated.
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