hjärtats

The heart is a muscular organ about the size of a clenched fist, located between the lungs in the thoracic cavity. It functions as the central component of the circulatory system, contracting rhythmically to propel blood through the pulmonary and systemic circuits. In Swedish, the word for heart is hjärta, and the possessive form hjärtats means “the heart’s,” used in phrases such as hjärtats vägg (the heart’s wall).

Anatomy and function: The heart has four chambers: two atria (upper) and two ventricles (lower). Blood flows from the right atrium through the tricuspid valve to the right ventricle, which pumps it to the lungs via the pulmonary artery. Oxygenated blood returns from the lungs to the left atrium via the pulmonary veins, passes through the mitral valve to the left ventricle, and is then pumped to the body via the aorta. Valves keep blood moving in a single direction and prevent backflow.

Conduction system: The heartbeat is coordinated by electrical impulses beginning in the sinoatrial (SA) node, often called the natural pacemaker, then passing to the atrioventricular (AV) node and along the bundle of His and Purkinje fibers to produce synchronized contractions.

Circulation and blood supply: The heart’s own blood supply comes from the coronary arteries, with venous drainage returning to the right atrium via the cardiac veins. Autonomic nervous system input and circulating hormones regulate heart rate and force of contraction to meet the body's needs.

Health and disease: Risk factors such as smoking, high blood pressure, diabetes, obesity, and physical inactivity affect heart health. Common conditions include coronary artery disease, arrhythmias, and heart failure.