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Exhalation (or expiration) is the flow of the breath out of an organism. In animals, it is the movement of air from the lungs out of the airways , to the external environment during breathing . This happens due to elastic properties of the lungs, as well as the internal intercostal muscles which lower the rib cage and decrease thoracic volume.
During exhalation (breathing out), at rest, all the muscles of inhalation relax, returning the chest and abdomen to a position called the "resting position", which is determined by their anatomical elasticity. [8] At this point the lungs contain the functional residual capacity of air, which, in the adult human, has a volume of about 2.5–3.0 ...
The normal relaxed state of the lung and chest is partially empty. Further exhalation requires muscular work. Inhalation is an active process requiring work. [4] Some of this work is to overcome frictional resistance to flow, and part is used to deform elastic tissues, and is stored as potential energy, which is recovered during the passive process of exhalation, Tidal breathing is breathing ...
The driving pressure forcing air into the lungs during inhalation is therefore halved at this altitude. The rate of inflow of air into the lungs during inhalation at sea level is therefore twice that which occurs at 5500 m. However, in reality, inhalation and exhalation occur far more gently and less abruptly than in the example given.
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 ...
During quiet breathing, there is little or no muscle contraction involved in exhalation; this process is simply driven by the elastic recoil of the lungs. When forceful exhalation is required, or when the elasticity of the lungs is reduced (as in emphysema), active exhalation can be achieved by contraction of the abdominal wall muscles (rectus ...
This decreases the pressure inside the lungs, forcing the air to flow into the lungs. During exhalation, the diaphragm relaxation causes a decrease in the thoracic cavity volume. The increased lung pressure pushes the air out of the lungs. [2] The primary function of ventilation is the replacement of the stale gases in the lungs with oxygen ...
The bicarbonate ion present in the blood plasma is transported to the lungs, where it is dehydrated back into CO 2 and released during exhalation. These hydration and dehydration conversions of CO 2 and H 2 CO 3, which are normally very slow, are facilitated by carbonic anhydrase in both the blood and duodenum. [7]