The heart is a hollow, four-chambered muscular pump about the size of a closed fist, weighing roughly 250-350 g in adults. Its right side receives deoxygenated blood from the body and pumps it to the lungs, while its left side receives oxygenated blood from the lungs and pumps it around the body. Four valves keep blood moving in one direction, and a built-in electrical system sets the rhythm.
| Location | Middle mediastinum, inside the pericardial sac, behind the sternum and costal cartilages 2-6, with about two-thirds of its mass to the left of the midline. The apex points down, forward and to the left; the base faces backwards. |
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| Parts |
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| Nerve Supply | Cardiac plexus; Vagus nerves (parasympathetic, slows rate); Sympathetic cardiac nerves from cervical and upper thoracic (T1-T4) ganglia (raise rate and force) |
| Blood Supply | Right coronary artery; Left coronary artery (left anterior descending and circumflex branches) |
| Venous drainage |
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| Lymphatic drainage |
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Pumps blood through two circuits in series: the pulmonary circulation for gas exchange and the systemic circulation to deliver oxygen and nutrients to every tissue. At rest it moves about 5 litres of blood per minute, rising several-fold during hard exercise.
Resting heart rate, blood pressure and the response to exercise are basic markers of cardiovascular fitness. Chest pain on exertion, breathlessness out of proportion to effort, palpitations or fainting during exercise all warrant medical assessment before training continues. Coronary artery disease remains the leading cause of death worldwide, and regular aerobic exercise is one of the strongest protective factors.
Death of heart muscle caused by blockage of a coronary artery, usually from rupture of an atherosclerotic plaque with clot formation. It typically causes crushing central chest pain and needs emergency treatment.
A state in which the heart cannot pump enough blood to meet the body's needs, or can only do so at raised filling pressures. It causes breathlessness, fatigue and fluid retention.
An inherited thickening of the heart muscle, often of the septum. It is a leading cause of sudden cardiac death in young athletes.
