Cardiac Muscle Case Study

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Section A – Part II
Cardiac cycle or heartbeat
Blood enters and fills both atriums at the same time. When full the pressure causes the tricuspid and bicuspid valves to open and flows into the ventricles. Contraction (systole) of each atrium now forces any remaining blood into the ventricles. The ventricles now contract (systole) and atriums relax (diastole). The pressure closes the tricuspid and bicuspid valves (causes the first sound of the heart beat). The contraction of the ventricles opens the semi lunar valves, forcing blood into the pulmonary and aorta arteries. The ventricles now relax (diastole) and any backflow of blood causes the semilunar valves to close (causing the second sound of the heart beat). Cardiac muscle never tires. The heart has its own
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Without pressure blood would not move at all. Blood is always under pressure, but the amount of pressure varies in different blood vessels.
Blood is forced into the arteries under high pressure from the left ventricle, the region of highest pressure, it eventually re-enters the heart via the venae-cavaes into the right atrium the region of lowest pressure.

Normal adult blood pressure is 120/80 mmGH which is dependent on age. The top number is systole and the bottom is diastole. Diastole is the reading when the heart is relaxed and systole is when the ventricles of the heart contract (the working phase of the heart)
Hypertension (high blood pressure) is blood pressure that consistently remains above the normal level of 120/80. Things such as stress, kidney disease, smoking, too much alcohol and bad diet can cause high blood pressure
Hypotension (Low blood pressure) is when the blood pressure constantly remains below the normal level of 120/80. Things such as shock, haemorrhage, burns, some types of medication, dehydration, anaemia and allergic reactions can cause low blood

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