BIOC34H3 Lecture Notes - Lecture 12: Pulmonary Artery, Respiratory Quotient, Partial Pressure
Document Summary
Partial pressures of gases throughout the circulatory system. In blood flowing through pulmonary artery into lungs, oxygen levels are low (40 mmhg) and co2 levels high (46 mmhg). The blood reaches the lungs, where it interacts with alveolar air: alveolar air is not same as atmospheric air; atmospheric air has a po2 of. Within mitochondria oxygen levels can be as low as 1 mmhg: deoxygenated blood flows through the venous system back to the right side of the heart, maintaining these partial pressure values until it returns to the lungs. Perfusion versus diffusion limitation: the uptake of o2 and excretion of co2 are perfusion limited. In the first 1/3 of the pulmonary capillary, the blood changes from being deoxygenated and high in co2 (40mmhg o2; 46mmhg co2) to being oxygenated and low in co2 (100mmhg o2; 40mmhg co2). This means we have a large reserve distance in lungs for gas exchange; 2/3 of capillary not used in gas exchange.
