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Basic cardiac anatomy & physiology
Anatomy
Position in chest
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The heart is cushioned between the lungs and is within the ribcage
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It s predominantly in the middle of the chest but is slightly off to the left side, and rotated to the left (apex of the heart points to the left).
Cardiac Chambers
There are four main heart chambers, including the
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right atrium
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left atrium
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right ventricle and
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left ventricle
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The atria receive blood from the body, and the ventricles pump blood to the body.
Cardiac Valves
There are four main heart valves, including the
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pulmonary valve
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tricuspid valve
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mitral valve and
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aortic valve
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Pulmonary valve (3 leaflets) allows blood flow from the RV to the pulmonary artery
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Tricuspid valve (3 leaflets) allows blood flow from the RA to the RV
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Mitral valve (2 leaflets) allows blood flow from the LA to the LV
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Aortic valve (3 leaflets - some congenital have 2 leaflets (bicuspid)) allows blood flow from the LV to the aorta
Physiology
Systemic circulation / Arterial System
Responsible for transferring oxygenated blood around the body.
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Oxygenated blood is received from the lungs into the LA via the pulmonary veins, is transferred to the LV and then to the Aorta which transfers through the arterial network to the rest of the body
Pulmonary circulation / Venous System
Responsible for transferring deoxygenated blood from the body back to the heart (completing the systemic circulation loop).
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Dexygenated blood is carried via the venous network to the RA via the SVC and IVC, is transferred to the RV and then to the lungs via the pulmonary artery.
Systole
The part of the cardiac cycle where the myocardium contracts ejecting blood from the heart.
Both the RV and LV contract in systole.
The aortic and pulmonary valves are open during systole.
The tricuspid and mitral valves are closed during diastole.
Atrial systole occurs just prior to ventricular systole (atrium contracting - mitral and tricuspid valves open)
Diastole
The part of the cardiac cycle where the myocardium relaxes and blood fills back into the heart.
The atria relax and receive blood from the veins.
The tricuspid and mitral valves are open during diastole.
The ventricles relax and receive blood from the atria.
The aortic and pulmonary valves are closed during diastole.
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