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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.
Gas exchange takes place in the gills which consist of thin or very flat filaments and lammellae which expose a very large surface area of highly vascularized tissue to the water. Other animals, such as insects , have respiratory systems with very simple anatomical features, and in amphibians , even the skin plays a vital role in gas exchange.
The process of breathing does not fill the alveoli with atmospheric air during each inhalation (about 350 ml per breath), but the inhaled air is carefully diluted and thoroughly mixed with a large volume of gas (about 2.5 liters in adult humans) known as the functional residual capacity which remains in the lungs after each exhalation, and ...
Real-time magnetic resonance imaging of the human thorax during breathing X-ray video of a female American alligator while breathing. Breathing (spiration [1] or ventilation) is the rhythmical process of moving air into and out of the lungs to facilitate gas exchange with the internal environment, mostly to flush out carbon dioxide and bring in oxygen.
The conduction zone conducts air breathed in that is filtered, warmed, and moistened, into the lungs. It represents the 1st through the 16th division of the respiratory tract. The conducting zone is most of the respiratory tract that conducts gases into and out of the lungs but excludes the respiratory zone that exchanges gases.
The alveolar and pulmonary capillary gases equilibrate across the thin blood–air barrier. [34] [68] [69] This thin membrane (about 0.5 –2 μm thick) is folded into about 300 million alveoli, providing an extremely large surface area (estimates varying between 70 and 145 m 2) for gas exchange to occur. [68] [70]
In the oxygen-rich capillaries of the lung, this property causes the displacement of carbon dioxide to plasma as low-oxygen blood enters the alveolus and is vital for alveolar gas exchange. The general equation for the Haldane Effect is: H + + HbO 2 ⇌ H + Hb + O 2; However, this equation is confusing as it reflects primarily the Bohr effect.
The respiratory center receives input from chemoreceptors, mechanoreceptors, the cerebral cortex, and the hypothalamus in order to regulate the rate and depth of breathing. Input is stimulated by altered levels of oxygen , carbon dioxide , and blood pH , by hormonal changes relating to stress and anxiety from the hypothalamus, and also by ...