CBNS 120 QUESTIONS WITH VERIFIED ANSWERS
The slow AHP (after-hyperpolarization lasting for tens of milleseconds to seconds)
results from: - Answers - Calcium Activated gK
In the Hodgkin-Huxley squid axon experiments, the late outward current could be
isolated by: - Answers - B & C Only (treating the axon with TTX (tetrodotoxin) &
Stepping the membrane potential to the Na equilibrium potential)
At threshold for the action potential: - Answers - The outward leak K current equals the
inward Na Current
Hodgkin and Huxley theorized movement of 4 "n" gating particles from position "1-n" to
"n" to describe: - Answers - K current activation
In Hodgkin-Huxley's mathematical tour de force, the "h" particle corresponds to: -
Answers - The Na Channel inactivation particle
Steady state inactivation can be decreased by: - Answers - Hyperpolarizing conditioning
voltage steps
Na current during the rising phase of the action potential decreases due to: - Answers -
decreased driving force
Given high values of gNa and gK, at membrane potentials positive to ENa: - Answers -
B & C (Na moved outward and K moved outward)
Spike frequency adaptation can be reduced by: - Answers - all of the above:
-Reducing [Ca2+]0
-Persistent gNa+
-Exposure to Cd2+
Gating current correponds to: - Answers - Movement of voltage sensors
The "Absolute Refractory Period" results from: - Answers - a & b only
-elevated threshold
Na Channel inactivation
The "Relative Refractory Period" results from: - Answers - b & c only
-elevated threshold
-k channel activation
Increasing the length of the "chain" in Shaker K channels: - Answers - slows inactivation
, The structural basis for Na channel inactivation involves: - Answers - b & c
-the IFM sequence motif
-the cytoplasmic loop that connects Domain III to Domain IV
Drugs or toxins that slow or block Na channel inactivation would: - Answers - b &C
-prolong the duration of the action potential
-diminish the refractory period
Myocardial cells have comparatively long duration action potentials because of: -
Answers - activation of gCa
Currents in the Hodgkin-Huxley equations include: - Answers - all of the above
-I k
-I Na
-I C
During the relative refractory period: - Answers - b & c
-action potential initiation can be accomplished by imposing a stronger stimulus
-threshold is elevated
Persistent Na current (INaP): - Answers - all of the above
- can cause repetitive action potential
-produces an after depolarization
- can oppose the influence of I K Ca
During the absolute refractory period: - Answers - all of the above
-gK is high
-Sodium channels are inactivated
-threshold is essentially infinite
As the number of myelin wraps around an axon increases: - Answers - a & c
-r in increases
-r i decreases
-Cin decreases
Which of the following would increase conduction velocity in an unmyelinated axon -
Answers - A & B only
-increasing axon radius
-decreasing T
Purkinje neurons: - Answers - all of the above
-have voltage gated Ca2+ channels in their dendrites
-have somatic Na+ action potentials
-have dendritic action potentials
Gap junctions: - Answers - all of the above
The slow AHP (after-hyperpolarization lasting for tens of milleseconds to seconds)
results from: - Answers - Calcium Activated gK
In the Hodgkin-Huxley squid axon experiments, the late outward current could be
isolated by: - Answers - B & C Only (treating the axon with TTX (tetrodotoxin) &
Stepping the membrane potential to the Na equilibrium potential)
At threshold for the action potential: - Answers - The outward leak K current equals the
inward Na Current
Hodgkin and Huxley theorized movement of 4 "n" gating particles from position "1-n" to
"n" to describe: - Answers - K current activation
In Hodgkin-Huxley's mathematical tour de force, the "h" particle corresponds to: -
Answers - The Na Channel inactivation particle
Steady state inactivation can be decreased by: - Answers - Hyperpolarizing conditioning
voltage steps
Na current during the rising phase of the action potential decreases due to: - Answers -
decreased driving force
Given high values of gNa and gK, at membrane potentials positive to ENa: - Answers -
B & C (Na moved outward and K moved outward)
Spike frequency adaptation can be reduced by: - Answers - all of the above:
-Reducing [Ca2+]0
-Persistent gNa+
-Exposure to Cd2+
Gating current correponds to: - Answers - Movement of voltage sensors
The "Absolute Refractory Period" results from: - Answers - a & b only
-elevated threshold
Na Channel inactivation
The "Relative Refractory Period" results from: - Answers - b & c only
-elevated threshold
-k channel activation
Increasing the length of the "chain" in Shaker K channels: - Answers - slows inactivation
, The structural basis for Na channel inactivation involves: - Answers - b & c
-the IFM sequence motif
-the cytoplasmic loop that connects Domain III to Domain IV
Drugs or toxins that slow or block Na channel inactivation would: - Answers - b &C
-prolong the duration of the action potential
-diminish the refractory period
Myocardial cells have comparatively long duration action potentials because of: -
Answers - activation of gCa
Currents in the Hodgkin-Huxley equations include: - Answers - all of the above
-I k
-I Na
-I C
During the relative refractory period: - Answers - b & c
-action potential initiation can be accomplished by imposing a stronger stimulus
-threshold is elevated
Persistent Na current (INaP): - Answers - all of the above
- can cause repetitive action potential
-produces an after depolarization
- can oppose the influence of I K Ca
During the absolute refractory period: - Answers - all of the above
-gK is high
-Sodium channels are inactivated
-threshold is essentially infinite
As the number of myelin wraps around an axon increases: - Answers - a & c
-r in increases
-r i decreases
-Cin decreases
Which of the following would increase conduction velocity in an unmyelinated axon -
Answers - A & B only
-increasing axon radius
-decreasing T
Purkinje neurons: - Answers - all of the above
-have voltage gated Ca2+ channels in their dendrites
-have somatic Na+ action potentials
-have dendritic action potentials
Gap junctions: - Answers - all of the above
