Gas Exchange. By Adriana Jimenez & Daisy Martinez. Ventilation, or breathing, is the alternate inspiration (inhaling) and expiration (exhalation) of air. Terrestrial vertebrates rely on ventilation to maintain high O2 and low CO2 concentrations at the gas exchange surface.
1. blood arriving at the lungs via the pulmonary arteries has a lower Po2 and a higher P co2 than the air in the alveoli.
2. by the time the blood leaves the lungs in the pulmonary veins, its Po2 has been raised and its Pco2 has been lowered.
After returning to the heart, this blood is pumped through the systematic circuit.
3. in the tissue capillaries, gradients of partial pressure favor the diffusion of o2 out of the blood and co2 into the blood.
Because cellular respiration removes o2 from and adds co2, to the interstitial fluid. (by diffusion, from mitochondria in nearby cells.)
4. after the blood unloads o2 and loads co2 it is returned to the heart and pumped to the lungs again.
Where it exchanges gases with air in the alveoli.
(b) pH&Hemoglobin Dissociation