physio EX 9.0 EXERCISE 6 act 5 Help!! please

Which ion(s) at least initially lowered the frog heart rate in the activity you just performed?
    potassium
    potassium and sodium
    sodium
    calcium, potassium and sodium
    calcium

What effect does potassium have on the resting membrane potential of the cardiac cell?
    Increasing extracellular potassium causes the resting membrane potential to become more positive.
    Changes in potassium have no effect on the resting membrane potential.
    Increasing extracellular potassium causes the resting membrane potential to become more negative.
    Increasing intracellular potassium causes the resting membrane potential to become more positive.


The cardiac cell plasma membrane is most permeable to _______________________.
    It is equally permeable to all ions.
    calcium
    sodium
    potassium


Calcium channel blockers block the movement of calcium _______.
    out of the cell and decrease heart rate
    out of the cell and increase heart rate
    into the cell and increase heart rate
    into the cell and decrease heart rate



A ___________________ drug increases the force of contraction of the heart.
    negative inotropic
    positive inotropic
    negative chronotropic
    positive chronotropic