alveolocapillær

Alveolocapillary refers to the microscopic structure within the lungs responsible for gas exchange. It is a functional unit comprising the alveoli and the capillaries that surround them. The alveoli are tiny air sacs where oxygen enters the bloodstream and carbon dioxide is removed. These sacs are extremely thin-walled, creating a very short diffusion distance for gases.

The capillaries are the smallest blood vessels in the body, forming a dense network around each alveolus. Their walls are also exceedingly thin, typically a single layer of endothelial cells. This intimate contact and thin barrier between the air in the alveoli and the blood in the capillaries facilitates efficient diffusion of oxygen from the inhaled air into the blood and carbon dioxide from the blood into the air to be exhaled.

The total surface area of the alveolocapillary membrane in a healthy adult human lung is vast, estimated to be between 70 and 100 square meters. This large surface area, combined with the thinness of the membrane and the continuous flow of blood through the capillaries and air through the alveoli, maximizes the rate of gas exchange. Any impairment to this structure, such as thickening of the membrane or reduced capillary blood flow, can significantly hinder oxygen uptake and carbon dioxide removal, leading to respiratory distress.