This video covers the partial pressures of oxygen in the veins, arteries, atmosphere, and alveoli. It goes into depth on how the oxygen gets to lower pressures vs higher pressures, and briefly covers PCO2 levels in the viens and arteries. The tutor also explains why it would be bad for a PCO2 level to fluctuate into drastically vs PO2 levels. Questions: What is the PO2 in respiration?