NSG 531 ADVANCED PHARMACOLOGY
EXAM 4 ACTUAL EXAM PAPER 2026
QUESTIONS WITH ANSWERS GRADED A+
⩥ What are the 5 phases of the non-pacemaker action potential? Answer:
0 - depolarization
1 - partial repolarization
2 - plateau
3 - repolarization
4 - resting membrane potential
⩥ what happens during phase 0 of the non-pacemaker action potential
Answer: depolarization
voltage gated sodium channels are opening up until we get past
threshold
⩥ what happens during phase 1 of the non-pacemaker action potential
Answer: partial repolarization
⩥ what happens during phase 2 of the non-pacemaker action potential
Answer: plateau
calcium channels open (L-type because they are long)
potassium is still open
,potassium out and calcium in - they are opposing each other in voltage
giving the plateau
this is when the ventricles are filling
⩥ what happens during phase 3 of the non-pacemaker action potential
Answer: repolarization
calcium channels are closed
potassium channels are the only thing open taking their positive charge
with them making the interior more negative
⩥ what happens during phase 4 of the non-pacemaker action potential
Answer: resting membrane potential where we are in between action
potentials there is no net change in ovltage inside the cell
⩥ When does contraction take place? Answer: begins towards the end of
repolarization and ends at some point during repolarization
⩥ refractory period Answer: during phase 0, 1, 2, and part of phase 3 the
cell is refractory to the initiation of new action potentials
many antiarrhythmic drugs increase the Refractory period which reduces
myocyte excitability
⩥ what are the benefits of the refractory period Answer: limits frequency
of cardiac contractions
,allows for adequate filling time
prevents sustained contractions
⩥ how are pacemaker cells different from non-pacemaker cell Answer:
no resting membrane potential - no point where it is flat
there are very few sodium channels in pacemaker - sodium channels are
not driving depolarization - calcium is
only 3 phases
comprised of cells within the SA node
generate regular, spontaneous action potentials
⩥ what are the phases of pacemaker action potential Answer: 0 - rapid
depolarization
3 - repolarization
4 - slow depolarization
⩥ what happens during phase 0 of the pacemaker action potential
Answer: Rapid depolarization
something is coming to open voltage gated calcium channels (L-type)
calcium comes rushing in
⩥ what happens during phase 3 of the pacemaker action potential
Answer: repolarization
potassium channels now open up, potassium rushes out, repolarizes
, ⩥ what happens during phase 4 of the pacemaker action potential
Answer: slow depolarization
with potassium rushing out we are all the way down at -60
funny sodium channels open up until voltage reaches -50
T-type (transient) calcium channels open up until voltage reaches -40
L-type calcium channels then open back up
⩥ Describe how non-pacemaker APs can mimic pacemkaer APs
Answer: Hypoxia and ischemia
when the resting membrane potential is not getting enough oxygen it is
going to become more positive because you need oxygen to produce
ATP. If we are deficient in ATP then the NA K ATPase pump wont be
functioning
if someone is hypoxic in a focal area - say they have a resting membrane
potential at -45 - the fast sodium channels won't open - they start using
calcium to open - so they would convert into action potentials that use
calcium (hence how they mimic pacemaker APs)
⩥ excitation-contraction coupling Answer: sequence of events from
motor neuron signaling to a skeletal muscle fiber to contraction of the
fiber's sarcomeres
conversion of depolarizing currents into contractile force
EXAM 4 ACTUAL EXAM PAPER 2026
QUESTIONS WITH ANSWERS GRADED A+
⩥ What are the 5 phases of the non-pacemaker action potential? Answer:
0 - depolarization
1 - partial repolarization
2 - plateau
3 - repolarization
4 - resting membrane potential
⩥ what happens during phase 0 of the non-pacemaker action potential
Answer: depolarization
voltage gated sodium channels are opening up until we get past
threshold
⩥ what happens during phase 1 of the non-pacemaker action potential
Answer: partial repolarization
⩥ what happens during phase 2 of the non-pacemaker action potential
Answer: plateau
calcium channels open (L-type because they are long)
potassium is still open
,potassium out and calcium in - they are opposing each other in voltage
giving the plateau
this is when the ventricles are filling
⩥ what happens during phase 3 of the non-pacemaker action potential
Answer: repolarization
calcium channels are closed
potassium channels are the only thing open taking their positive charge
with them making the interior more negative
⩥ what happens during phase 4 of the non-pacemaker action potential
Answer: resting membrane potential where we are in between action
potentials there is no net change in ovltage inside the cell
⩥ When does contraction take place? Answer: begins towards the end of
repolarization and ends at some point during repolarization
⩥ refractory period Answer: during phase 0, 1, 2, and part of phase 3 the
cell is refractory to the initiation of new action potentials
many antiarrhythmic drugs increase the Refractory period which reduces
myocyte excitability
⩥ what are the benefits of the refractory period Answer: limits frequency
of cardiac contractions
,allows for adequate filling time
prevents sustained contractions
⩥ how are pacemaker cells different from non-pacemaker cell Answer:
no resting membrane potential - no point where it is flat
there are very few sodium channels in pacemaker - sodium channels are
not driving depolarization - calcium is
only 3 phases
comprised of cells within the SA node
generate regular, spontaneous action potentials
⩥ what are the phases of pacemaker action potential Answer: 0 - rapid
depolarization
3 - repolarization
4 - slow depolarization
⩥ what happens during phase 0 of the pacemaker action potential
Answer: Rapid depolarization
something is coming to open voltage gated calcium channels (L-type)
calcium comes rushing in
⩥ what happens during phase 3 of the pacemaker action potential
Answer: repolarization
potassium channels now open up, potassium rushes out, repolarizes
, ⩥ what happens during phase 4 of the pacemaker action potential
Answer: slow depolarization
with potassium rushing out we are all the way down at -60
funny sodium channels open up until voltage reaches -50
T-type (transient) calcium channels open up until voltage reaches -40
L-type calcium channels then open back up
⩥ Describe how non-pacemaker APs can mimic pacemkaer APs
Answer: Hypoxia and ischemia
when the resting membrane potential is not getting enough oxygen it is
going to become more positive because you need oxygen to produce
ATP. If we are deficient in ATP then the NA K ATPase pump wont be
functioning
if someone is hypoxic in a focal area - say they have a resting membrane
potential at -45 - the fast sodium channels won't open - they start using
calcium to open - so they would convert into action potentials that use
calcium (hence how they mimic pacemaker APs)
⩥ excitation-contraction coupling Answer: sequence of events from
motor neuron signaling to a skeletal muscle fiber to contraction of the
fiber's sarcomeres
conversion of depolarizing currents into contractile force
