Question 1
If the membranes of the cardiac muscle cells in the SA node become more permeable to potassium ions,
◦ the membrane will depolarize.
◦ heart rate will decrease.
◦ heart rate will increase.
◦ stroke volume will increase.
◦ intracellular concentration of calcium ion will increase.
Question 2
As a result of the long refractory period, cardiac muscle prevents
◦ fatigue.
◦ treppe.
◦ tonus.
◦ tetanus.
◦ recruitment.