Inima

Inima, the Romanian word for heart, refers to the muscular organ that powers circulation in humans and many animals. In humans, the heart lies in the thoracic cavity between the lungs, slightly left of center. It has four chambers: two atria and two ventricles. Blood flows through valves: the tricuspid and pulmonary valves on the right, and the mitral and aortic valves on the left. The heart wall is formed by three layers—epicardium, myocardium, and endocardium—with the myocardium providing the contractile force.

The heart's intrinsic conduction system coordinates rhythm: the sinoatrial node serves as the natural pacemaker, the atrioventricular node provides a critical delay, and the His–Purkinje network distributes impulses to the ventricles. This electrical activity drives the cardiac cycle, which includes atrial systole, ventricular systole, and diastole when the chambers refill.

The heart operates in two circulations: pulmonary circulation, delivering deoxygenated blood to the lungs for oxygenation, and systemic circulation, distributing oxygenated blood to the body. The coronary arteries supply the heart muscle itself. Nerves and hormones modulate heart rate and contraction strength.

Common diseases affect structure or rhythm, including coronary artery disease, arrhythmias, valvular disease, and heart failure. Diagnosis relies on physical examination, electrocardiography (ECG), and imaging such as echocardiography. Developmentally, the heart forms from mesodermal precursors during embryogenesis, resulting in a four-chamber organ. The pericardium, a double-walled sac, surrounds and protects the heart.