fourchambered

Fourchambered is an adjective used in biology and anatomy to describe structures that contain four compartments or cavities. In anatomy, a fourchambered heart is defined by two atria and two ventricles, with a complete separation between the pulmonary and systemic circulations.

In vertebrate hearts, the four-chambered arrangement enables efficient separation of oxygen-rich and oxygen-poor blood. In mammals and birds, the left side receives oxygenated blood from the lungs and pumps it to the body, while the right side handles deoxygenated blood from the body and moves it to the lungs. This division supports high metabolic demands and endothermy in many species.

Some reptiles, notably crocodilians, also possess a four-chambered heart. However, they can exhibit a partial blood shunt through a structure known as the foramen of Panizza, allowing blood to bypass the lungs under certain conditions. Despite this, the heart generally maintains distinct arterial flows, approaching a complete four-chambered arrangement in function.

Evolutionarily, four-chambered hearts have appeared more than once in vertebrates. Mammals and birds show a fully separated, four-chambered heart, linked to high activity levels and metabolic rates. Crocodilians possess a four-chambered heart as well, representing another independent adaptation within the archosaur lineage.

In broader usage, fourchambered may be applied to any object or concept characterized by four internal compartments, though in scientific contexts it most commonly refers to cardiac anatomy.