KIN110 Lecture Notes - Lecture 17: Vasomotor Center, Vascular Smooth Muscle, Capillary Pressure
Document Summary
Important that the blood pressure is low in the capillaries so that the capillaries don"t burst. Mean arteriole pressure is the combined average of the diastolic and systolic pressure and is responsible for driving the ow of blood through the systemic circuit. Systolic pressure: pressure exerted during ventricular contraction. Mean arteriole pressure (map): pressure that propels the blood to the tissues. Map = diastolic pressure + 1/3 pulse pressure. Pulse pressure = systolic diastolic eg. 120 80 = 40. Pule pressure and map both decline with increasing distance from the heart map = 80mm + 40mm/3 = 93mm. Low capillary pressure is desirable because high bp would rupture fragile thin- walled capillaries. Most capillaries are very permeable, so low pressure forces ltrate into interstitial spaces. Factors aiding venous return of blood to the heart. Repiratory pump : pressure changes created during breathing move blood toward the heart by squeezing abdominal veins as thoracic veins expand.