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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.
Ventilation (or breathing) is the air movement between the lungs and the atmospheric air, facilitating gas exchange. The air rushes into the lungs through inhalation (inspiration) and is pushed out through exhalation (expiration). [2]
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 anatomical structure of the lungs is less complex in reptiles than in mammals, with reptiles lacking the very extensive airway tree structure found in mammalian lungs. Gas exchange in reptiles still occurs in alveoli however. [44] Reptiles do not possess a diaphragm. Thus, breathing occurs via a change in the volume of the body cavity which ...
Small sacs called atria radiate from the walls of the tiny passages; these, like the alveoli in other lungs, are the site of gas exchange by simple diffusion. [108] The blood flow around the parabronchi and their atria forms a cross-current process of gas exchange (see diagram on the right). [106] [107]
The respiratory zone includes the respiratory bronchioles, alveolar ducts, and alveoli, and is the site of oxygen and carbon dioxide exchange with the blood. The respiratory bronchioles and the alveolar ducts are responsible for 10% of the gas exchange. The alveoli are responsible for the other 90%.
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 ...
Tidal volume: that volume of air moved into or out of the lungs during quiet breathing (VT indicates a subdivision of the lung; when tidal volume is precisely measured, as in gas exchange calculation, the symbol TV or V T is used.) FRC: Functional residual capacity: the volume in the lungs at the end-expiratory position: RV/TLC%