PHYS 1302 Lecture 12: ch-18-gas-exchange-and-transport
Document Summary
To avoid hypoxia and hypercapnia, body uses sensors to monitor arterial blood composition by responding to 3 variables: Breathing is the bulk flow of air into and out of the lungs. Once air reaches alveoli, individual gases like o2 and co2 diffuse (high to low partial pressure) from alveolar space into the blood. Then, oxygen flows down gradient from blood plasma to working cells. Co2 diffuses out of cells and into the capillaries. At pulmonary capillaries, co2 moves from blood plasma capillaries into alveoli. Many variables influence efficiency of alveolar gas exchange. Po2 in air decreases when altitude increases. Due to low volumes of fresh air entering alveoli. Can happen because of decreased lung compliance, increased airway resistance, or cns depression that slows ventilation rate (from alcohol poisoning, drug overdoses, etc. ) Diffusion is most rapid over short distances. Emphysema loss of alveolar surface area.
