![]() ![]() The gases diffuse across the barrier following pressure gradients. ![]() Gas exchange occurs via simple diffusion across the blood-air barrier. Diseases that affect the perfusion (e.g., pulmonary embolism) or ventilation (e.g., foreign body aspiration) can cause a V/Q mismatch. The Euler-Liljestrand mechanism regulates the perfusion of nonventilated alveoli: if a lung section is perfused but not ventilated, there will be a drop in the oxygen concentration in the blood, resulting in hypoxic vasoconstriction. The ventilation-perfusion ratio is higher in the apex of the lung than at its base. Perfusion of the pulmonary capillaries is closely regulated to match ventilation in order to maximize gas exchange. The physiologic dead space is the volume of inspired air that does not participate in gas exchange. Ventilation is the movement of air through the respiratory tract into (inspiration) and out of (expiration) the respiratory zone ( lungs). This part is known as the conducting zone and it does not take part in gas exchange.The main function of the respiratory system is gas exchange (O 2 and CO 2). So, the part of the respiratory tree prior to these alveoli, starting from the nose, or the mouth, right up to the tiny terminal tiny bronchioles without these alveoli, merely acts to conduct or transport air to the alveoli. Within the lungs, the bronchi divide into progressively smaller and smaller bronchioles until air gets down to tiny thin-walled air-sacs called alveoli which are surrounded by tiny capillaries. Normally, during an inhale - the diaphragm and chest muscles contract to pull open the chest and that sucks in air like a vacuum cleaner, and then during an exhale - the muscles relax, allowing the lungs to spring back to their normal size pushing that air out.īut as it turns out, not all the air that we breathe in, ends up participating in gas exchange.Īs we inhale, air enters the nasal cavity or the oral cavity and travels down the trachea and then splits into the two mainstem bronchi and enters the two lungs. The main job of the lungs is gas exchange, pulling oxygen into the body and getting rid of carbon dioxide. ![]()
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