BIOC34H3 Lecture Notes - Lecture 5: Stroke Volume, Coronary Circulation, Cardiac Muscle
Document Summary
Lecture 6: stroke volume regulation (continued) and heart failure: stroke volume regulation continued. Factors affecting end diastolic volume: the skeletal muscle pump. The third factor to influence end diastolic volume, the skeletal muscle pump, serves to move blood up toward the heart when it is contracting, and to prevent blood backflow when the heart is relaxing. This obviously influences both end diastolic pressure (pre-load) and, therefore, edv. When the muscle contracts, the increase in pressure cause the distal valve to close and the proximal valve to open, forcing blood upwards towards the heart through the open proximal valve. Blood does not flow backward because the distal valve is closed. When the heart relaxes, the opposite occurs: the proximal valve closes and the distal valve opens. Blood that has previously been forced upwards towards the heart does not simply fall back into the muscle when the heart relaxes because the proximal valve is closed.
