Hey, this confused me too but after reading the book more carefully, it makes more sense now
Basically, the difference is that the responses take place BEFORE, DURING and towards the END of exercise.
- At the start of exercise, adrenaline is released which dilates vessels and blood pressure falls. Baroreceptors detect a fall in pressure and stimulates the CVC which sends impulses down the sympathetic nerve to increase heart rate and blood pressure (Negative feedback). This is good before exercise as it INCREASES CARDIAC OUTPUT.
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At the beginning of exercise, more blood returns to the heart from the veins due to sudden increase in movement so more blood flows to the atria and more receptors are stretched which send impulses to the CVC that stimulates the sympathetic nerve to increase heart rate. Also, like 'chemdweeb' said, stroke volume also increases...it's not affected by the CVC however- the cardiac muscle contracts harder due to increased stretching so stroke volume increases and overall cardiac output will increase.
- However, DURING and towards the END of exercise, baroreceptors in carotid arteries etc send impulses to the CVC which stimulates the parasympathetic nerve to slow down the heart rate and dilates blood vessels to lower blood pressure (Negative feedback)
That's what I think - let me know if there are any mistakes etc. but hope it helps
As for the baroreceptors and chemoreceptors, I usually use baroreceptors when referring to heart rate and chemoreceptors with breathing rate. Of course, chemoreceptors affect heart rate too but apparently it's not a direct effect but related to their effect on the stretch receptors that detect changes in ventilation rate which in turn increases heart rate so ultimately, it's the baroreceptors that are controlling the heart rate in both cases.