- ΨετμουνΤLv 71 decade agoFavorite Answer
Gas exchange in humans and mammals
In humans and other mammals, respiratory gas exchange or ventilation is carried out by mechanisms of the lungs. The actual exchange of gases occurs in the alveoli.
Convection occurs over the majority of the transport pathway. Diffusion occurs only over very short distances. The primary force applied in the respiratory tract is supplied by atmospheric pressure. Total atmospheric pressure at sea level is 760 mm Hg, with oxygen (O2) providing a partial pressure (pO2) of 160 mm Hg, 21% by volume, at the entrance of the nares, and an estimated pO2 of 100 mm Hg in the alveoli sac, pressure drop due to conduction loss as oxygen travels along the transport passageway. Atmospheric pressure decreases as altitude increases making effective breathing more difficult at higher altitudes.
Gas exchange occurs only at pulmonary and systemic capillary beds.
CO2 is a result of cellular respiration. The concentration of this gas in the breath can be measured using a capnograph. As a secondary measurement, respiration rate can be derived from a CO2 breath waveform.
Trace gases present in breath at levels lower than a part per million are ammonia, acetone, isoprene. These can be measured using SIFT-MS selected ion flow tube mass spectrometry.
Transporting of oxygen, carbon dioxide, and hydrogen ions
Blood carries oxygen, carbon dioxide and hydrogen ions between tissues and the lungs.
The majority (70%) of CO2 transported in the blood is dissolved in plasma (primarily as dissolved bicarbonate; 60%). A smaller fraction (30%) is transported in red blood cells combined with the globin portion of hemoglobin as carbaminohemoglobin.Source(s): http://en.wikipedia.org/wiki/Gas_exchange
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