the heart

Cardiology

The study of the heart and its disorders.

Cardiovascular system

Consists of the heart and blood vessels.

Heart

A pump that keeps blood flowing through the vessels.

Arteries

Vessels that carry blood away from the heart.

Veins

Vessels that carry blood toward the heart.

Capillaries

Microscopic vessels that connect the smallest arteries to the smallest veins.

Pulmonary circuit

Carries blood to the lungs for gas exchange and back to the heart.

Systemic circuit

Supplies oxygenated blood to all tissues of the body and returns it to the heart.

Pericardium

A double-walled sac enclosing the heart.

Epicardium

The serous membrane covering the heart.

Myocardium

The layer of cardiac muscle in the heart.

Endocardium

The smooth inner lining of the heart and blood vessels.

Atrioventricular (AV) valves

Valves that control blood flow between atria and ventricles.

Semilunar valves

Valves that control flow from ventricles into great arteries.

Cardiac cycle

One complete contraction and relaxation of all four chambers of the heart.

Angina pectoris

Chest pain from partial obstruction of coronary blood flow.

Myocardial infarction (MI)

Sudden death of a patch of myocardium due to long-term obstruction of coronary circulation.

SA node

The sinoatrial node, the heart's natural pacemaker.

ECG (Electrocardiogram)

A recording of the electrical activity of the heart.

Systole

Contraction phase of the heart.

Diastole

Relaxation phase of the heart.

Valvular insufficiency

Failure of a valve to prevent the backward flow of blood.

Cardiac output (CO)

The amount ejected by each ventricle in one minute.

Coronary artery disease (CAD)

Degenerative disease in coronary arteries usually resulting from atherosclerosis.

Ectopic focus

A region of spontaneous firing in the heart other than the SA node.

Heart sounds

Sounds made by the heart during the cardiac cycle.

Stroke volume (SV)

The amount of blood ejected by the ventricle per heartbeat.

Tachycardia

Persistent, resting adult heart rate above 100 beats per minute.

Bradycardia

Persistent, resting adult heart rate below 60 beats per minute.

Cardiac arrhythmias

Deviations of ECG from normal rhythm.

Coronary bypass graft (CABG)

A surgical procedure to divert blood around blocked coronary arteries.

Cardiac conduction system

The system that propagates electrical signals in the heart for rhythmic contractions.