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Gas exchange is the physical process by which gases move passively by diffusion across a surface. For example, this surface might be the air/water interface of a water body, the surface of a gas bubble in a liquid, a gas-permeable membrane, or a biological membrane that forms the boundary between an organism and its extracellular environment.
The concentration of carbon dioxide (CO 2) rises in the blood when the metabolic use of oxygen (O 2), and the production of CO 2 is increased during, for example, exercise. The CO 2 in the blood is transported largely as bicarbonate (HCO 3 − ) ions, by conversion first to carbonic acid (H 2 CO 3 ), by the enzyme carbonic anhydrase , and then ...
Inhaled air is by volume 78% nitrogen, 20.95% oxygen and small amounts of other gases including argon, carbon dioxide, neon, helium, and hydrogen. [18] The gas exhaled is 4% to 5% by volume of carbon dioxide, about a hundredfold increase over the inhaled amount. The volume of oxygen is reduced by about a quarter, 4% to 5%, of total air volume.
Gas exchange in the lungs occurs in millions of small air sacs; in mammals and reptiles, these are called alveoli, and in birds, they are known as atria. These microscopic air sacs have a very rich blood supply, thus bringing the air into close contact with the blood. [ 2 ]
These changes ultimately result in an increased exchange of oxygen and carbon dioxide, which is accompanied by an increase in metabolism. [2] Respiratory adaptation is a physiological determinant of peak endurance performance, and in elite athletes, the pulmonary system is often a limiting factor to exercise under certain conditions.
In mammals, physiological respiration involves respiratory cycles of inhaled and exhaled breaths. Inhalation (breathing in) is usually an active movement that brings air into the lungs where the process of gas exchange takes place between the air in the alveoli and the blood in the pulmonary capillaries .
The absorption of gases in liquids depends on the solubility of the specific gas in the specific liquid, the concentration of gas (customarily expressed as partial pressure) and temperature. [2] In the study of decompression theory, the behaviour of gases dissolved in the body tissues is investigated and modeled for variations of pressure over ...
The main reason for exhalation is to rid the body of carbon dioxide, which is the waste product of gas exchange in humans. Air is brought into the lungs through inhalation. Diffusion in the alveoli allows for the exchange of O 2 into the pulmonary capillaries and the removal of CO 2 and other gases from the pulmonary capillaries to be exhaled ...