Why our normal heart beat ranges between 60_100 although the discharge of SA node is 105beats/min??
Because the vagus acts as parasympathetic nerve and reduces the heart rate by opening k+ channels and closing Na+ channels.
I think major effects on parasympathetic(vagal) action it depressed SA node that is why SA node rate will decrease so heart rate decrease
What are the physiological changes in exercise (changes in cardiovascular system)