After the Na+ ions migrate into the cell in response to depolarization, I
was told that the ca2+ ions enter the cell so as to make K+ ions migrate
out of the cell to bring the voltage down. I was also told that the
sodium-potasium pump kicks in and removes the Na+ to bring down the
voltage to resting potential. I am confused. Why does the ca2+ come in if
all the cell had to do was pump out the Na+ ions with the Na+/K+ pump?
also, I am confused on the details of why there is a short
hyperpolarization just after the voltage comes back down to resting
potential.
any input would be greatly appriciated.
thank you