Emptying Oil Tankers An oil tanker can be emptied by the main pump in 4 hours. An auxiliary pump can empty the tanker in 9 hours. If the main pump is started at 9 AM, when should the auxiliary pump be started so that the tanker is emptied by noon?
PSL 250 - Lecture 30 - Gas exchange Partial pressures ● Gas equivalent to concentration ● Sea level: 760 mmHg = 600 N2 + 160 O2 ● CO2 = 0.3 mmHg ● Gases are independent of one another. ● Air in lungs is water saturated. Alveolar air ● PO2 = 100 mmHg, PCO2 = 40. ● Venous blood: PO2 = 40, PCO2 = 46. ● The air pressure will always match the surrounding tissues concentration. ● Surrounding tissue 100 - match 100 with capillary. Diffusion through alveolar wall ● Gases follow partial pressure gradients ● Capillary gases match tissue it goes through. ● O2: O2 enters pulmonary capillaries until PO2 is 100 ● CO2: CO2 leaves pulmonary capillaries until PCO2 is 40 Pulmonary circulation ● Lower BP than aorta. ● ~15 - 20 mmHg MAP