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The heart and heart disease
Heart structure and function
Muscular organ
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Systole – contraction
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Atrioventricular valves link atria to ventricles and stop backflow [right
valve – tricuspid] [left valve - bicuspid]
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ð Pulmonary circulation – takes blood to the lungs
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The cardiac cycle
1
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ð Contraction of atria decreases volume of atria
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ð Slight increase in ventricular pressure and volume as blood is ejected into ventricles
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Ventricular systole – ventricles contract, atria relax
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ð Pressure in ventricles is greater than in atria – the atrioventricular valves shut
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3
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ð Higher pressure in pulmonary artery/ aorta than in ventricles – the semilunar valves shut
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ð Pressure of atria increase while the ventricles continue to relax
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ð Blood passively flows into ventricles
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1
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2
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3
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4
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5
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6
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Cardiac output
Cardiac output = heart rate × stroke volume
ð Stroke volume – volume of blood pumped with each heartbeat
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The biological basis of heart disease
Atheroma
ð If damage occurs to the endothelium of capillaries white blood cells and lipids clump to form a fatty
streak
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ð Constricts the blood vessels
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p
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ð Vessel can be weakened by atheroma plaques, which constrict vessels, which increases blood
pressure
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Thrombosis
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Fatty deposits develop under the endothelium
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Can lead to blood clot – thrombosis
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Myocardial infarction – heart attack
ð Result of interruption to blood flow to the heart muscle
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Risk factors of CHD
ð CHD – coronary heart disease, the build up of atheroma in the coronary arteries that supply blood to
the heart muscles
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ð Smoking – arteries constrict, reducing blood flow and increases blood pressure
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ð Exercise
ð Weight
ð Age

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