PHGY 210 Lecture Notes - Lecture 9: Alveolar Pressure, Slinky, Vascular Resistance
Document Summary
Iv pulmonary blood flow and ventilation-perfusion ratio: pulmonary circulation and blood pressure. In the pulmonary capillaries, blood is spread out in a multitude of thin-walled vessels which have a surface area of approximately 100 m2, or 40 times the body surface area. The pulmonary circulation differs in many ways from the systemic one. Blood pressure in the pulmonary circulation is lower than in the systemic circulation, and the walls of the pulmonary capillaries are thinner than those of similar vessels in the systemic circulation. Normally, the right ventricle develops a pressure of about 25 mmhg during its systole, and this is transmitted to the pulmonary arteries (figure. When systole ends, right ventricle pressure falls to atmospheric (taken to be 0). Since the pulmonary valves are now closed, blood pressure in the pulmonary circulation decreases gradually during diastole to a low of about 8 mmhg as blood flows through the pulmonary capillaries (figure 16).