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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 second sector is the capillary sector, which is represented by the capillaries, where substance and gas exchange between blood and interstitial fluid takes place. Finally, the post-capillary sector is represented by the post-capillary venules, which are formed by a layer of endothelial cells that allow free movement of some substances. [3]
There are two types of capillaries: true capillaries, which branch from arterioles and provide exchange between tissue and the capillary blood, and sinusoids, a type of open-pore capillary found in the liver, bone marrow, anterior pituitary gland, and brain circumventricular organs. Capillaries and sinusoids are short vessels that directly ...
A typical pair of human lungs contains about 480 million alveoli, [11] providing a total surface area for gas exchange of between 70 and 80 square metres. [10] Each alveolus is wrapped in a fine mesh of capillaries covering about 70% of its area. [12] The diameter of an alveolus is between 200 and 500 μm. [12]
Fig. 11 A highly diagrammatic illustration of the process of gas exchange in the mammalian lungs, emphasizing the differences between the gas compositions of the ambient air, the alveolar air (light blue) with which the pulmonary capillary blood equilibrates, and the blood gas tensions in the pulmonary arterial (blue blood entering the lung on ...
The blood–air barrier or air–blood barrier, (alveolar–capillary barrier or membrane) exists in the gas exchanging region of the lungs. It exists to prevent air bubbles from forming in the blood , and from blood entering the alveoli .
For the perfusion process, the circulatory organs of the cardiovascular system such as the heart, pulmonary arteries, pulmonary veins, and alveolar capillaries are involved. The alveolar capillary specifically participates in perfusion to get in contact with the alveoli for the gas exchange and oxygen delivery to the body tissues. [1]
Chloride shift (also known as the Hamburger phenomenon or lineas phenomenon, named after Hartog Jakob Hamburger) is a process which occurs in a cardiovascular system and refers to the exchange of bicarbonate (HCO 3 −) and chloride (Cl −) across the membrane of red blood cells (RBCs).