BIOC34H3 Lecture : Lecture_6_Notes.rtf
Document Summary
Lecture 6: stroke volume regulation (continued), afterload, and blood flow regulation: filling time, edv and sv. In the previous lecture we looked at factors affecting end diastolic volume (the amount of blood in the ventricles just before they contract) which is an important factor in determining stroke volume. We ended up looking at the effects of filling time on end diastolic volume; filling time is essentially the amount of time the heart spends in diastole. This limit on stroke volume can be countered by sympathetic stimulation. With sympathetic stimulation, the heart both beats faster, and relaxes faster. The increased rate is due to increased calcium mobilization (from the ecf and sr); the quicker relaxation time is due to the enhanced uptake of calcium by the sarcoplasmic reticulum. The heart therefore spends more time in diastole then in systole, giving extra time for it to fill with blood.