discuss the movement of nitrous oxide from the alveolus to the blood and ultimately to the central nervous system, and vice versa.
N2O is insoluble, therefore, there is fast uptake into the alveolus when inspired. Percentage of inspired N2O X 760mmHg is the partial pressure according to Dalton’s Law. This is the same partial pressure (tension) as in the blood (Henry’s Law). Use Blood/gas coefficient to calculate actual concentration of N2O in the blood (0.47 x Partial Pressure). The vessel rich groups pick up the N2O first, then the muscle group and finally the fat group. Since the brain is highly perfused, it’s concentration is almost the same as the arterial concentration. As we breathe a constant PP of the gas, over time the concentration in the brain increases. This is because as we breathe, there is a leak of N2O into surrounding tissues. Our body picks up more N2O everytime we breathe, so the concentration gradually rises as some leaks out to the VRG, MG and FG. N2O crosses the BBB, so gets into the brain quite readily and quickly.