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Area outside the Blood brain barrier are called Circumventricular organs Mnemonic - M arble SOAP M edian eminence S ub fornical organ O rganum vasculosum A rea postrema P osterior Pitutary

Blood volume in lungs= 450ml, 9% of total blood volume. Blood flowing through Bronchial arteries- 1-2% of total Cardiac Output Pulmonary Vascular resistance= 1/7 of systemic vascular resistance Mean pressure= 15mmHg Pulmonary arteries constrict in response to hypoxia. Perfusion and Ventilation both are more in lower lobes Ventilation/resistance is maximum at the apex. Pulmonary veins are collapsed in upper and middle lobes, distended in lower lobes. This is because pressure in pulmonary veins of upper and middle lobes is less than atmospheric pressure. This causes the veins to collapse.