Physio Ch. 18, Gas Exchange

hrdcorhrvivor's version from 2017-04-18 06:52


Question Answer
occurs in two placesbetween blood and alveoli and between blood and tissues
influenced byadequate o2 supply and perfusion
causes of low PO2air has low o2 content, alveolar ventilation is inadequate (hypoventilation)
diffusion of gasesproportional to surface area, concentration gradient, barrier permeability. inversely proportional to distance
emphysemawalls of alveoli break down, increased surface area decreased gas exchange
fibrotic lung diseasescar tissue is less permeable than healthy tissue. low permeability low gas exchange
pulmonary edemahigher fluid higher diffusion distance
solubility of oxygencan move into fluid according to pressure gradients, affects transport through body
solubility of co2unlike o2, more co2 will dissolve into liquid at same pressure
o2 transports in two wayson hemoglobin 98% and dissolved in plasma 2%. o2 binds directly to iron in hemoglobin up to 4 per heme
factors that affect o2 and hemoglobin bindingPO2 in plasma, number of hemoglobin binding sites available
percent saturationamound of hemoglobin bound to o2 at any given PO2, 100% bound = saturated, no significant change in saturation until PO2 < 60
right shift in saturation curvebohr effect. increased H+, temp, Pco2
left shift in saturation curvedecresed H+, temp, Pco2
CO2 transport 3 ways70% bicarbonate ion, 23% on hemoglobin as carbaminohemoglobin, 7% dissolved in plasma
bicarbonate ionsadditional way to transport CO2, acts as a buffer, requires enzyme carbonic anhydrase in RBCs
removal of CO2 at lungsPCO2 in alveoli is less than PCO2 in venous blood, co2 diffuses out of plasma into alveoli and exhaled