Physiology 3120 Lecture Notes - Lecture 6: Aortic Valve, Mean Arterial Pressure, Stroke Volume

• School: Western University
• Department: Physiology
• Course: Physiology 3120
• Professor: Tom Stavraky

Document Summary

Afterload is the resistance against which the ventricles pump blood (refers to ventricular wall stress during systole/contraction) The pressure in the aorta is the afterload encountered by the left ventricle, and the pressure in the pulmonary artery during systole is the afterload faced by the right ventricle. The left ventricle has to generate more pressure than the aorta to open the aortic valve -> the pressure in the aorta is the pressure the left ventricle is working against. This would increase the duration of phase 2 - the isometric contraction phase. Once the ventricular pressure has exceeded the aortic pressure, the aortic valve would open and blood could then be ejected. With a shorter time period to eject the blood, there would be less blood ejected and this means stroke volume decreases. How would the heart compensate for this drop in sv (and increase in.