BIO120H1 Lecture Notes - Lecture 5: Beta Blocker, Parasympathetic Nervous System, Stroke Volume
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BIO120H1 Full Course Notes
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If we block muscarinic receptors, heart rate will speed up. In the absence of any sympathetic or parasympathetic input, the pacemaker cells in the sa node usually depolarize around 100 times per minute, but resting heart rate is normally around. 60-70 beats per minute: in other words, resting heart rate is lower than the endogenous rate of unaltered sa node depolarization. = hr x sv, regulated: while regulation of heart rate was fairly simple, regulation of stroke volume is considerably more complex, with many more factors involved. 3 major factors will influence the regulation of stroke volume: the force of ventricular contraction. First, it will open up calcium channels on the plasma membrane, allowing ca2+ Second, it triggers further calcium release from the sarcoplasmic reticulum (sr) ions to flow into the cell also by opening calcium channels. Third, it facilitates the binding together of actin and myosin fibers which is required for muscle contraction.
