NEUROBIOLOGY ALL 2026 EXAMINATION SET QUESTIONS
AND ANSWERS GRADED A+
✔✔Nerst potential - ✔✔Equilibrium voltage at which chemical forces balance the
electrical forces, resulting in zero net ionic flow when a single ion species is considered
✔✔How is the resting potential maintained? (How do the ions move across the
membrane & why) - ✔✔There is an ongoing influx of Na+ and a matching efflux of K+
✔✔Know the contribution of Hodgkin & Huxley - ✔✔The axon experimentally to
accurately determine the resting and action potential a
✔✔Understand the Goldman-Hodgkin-Katz (GHK) equation - ✔✔The greater an ions
concentration and permeability, the more it contributes to resting membrane potential
✔✔What is an excitatory postsynaptic potential (EPSP) & how is one produced -
✔✔Brief depolarization of a membrane in response to stimulation, more likely to have
action potential, caused by influx of Na+
✔✔What is an inhibitory postsynaptic potential (IPSP) & how is one produced - ✔✔Brief
hyperpolarization of a membrane in response to stimulation, less likely to fire an action
potential, caused by influx of Cl- and efflux of K+
✔✔How does CTX, TTX & aconitine affect neuron physiology - ✔✔TTX blocks Na+
channels, depolarization, death in 4-6 hours
CTX blocks K+ channels causes hyperexcitability and paralysis
Aconitine: opens Na+ channels, causes death
✔✔Action potential (what ion channels are opened & closed during the phases of an
action potential) - ✔✔Ion channels open during action potential
Na influx, then K efflux
Depolarizing due to Na+ influx (in)
Hyperpolarizing due to K+ efflux (out)
✔✔Relative refractory period - ✔✔Later phase during which increased electrical current
is required to produce another action potential (open K+ channels, oppose Na+ current)
✔✔absolute refractory period - ✔✔During depolarizing and repolarizing period action
potential cannot be produced (Na+ channels recover)
✔✔Time constant - ✔✔Small membrane resistance decreases time constant
Large membrane resistance increases the time constant
Higher the permeability the lower the resistance
, ✔✔Length constant: - ✔✔small membrane resistance or large internal resistance
decreases length constant
Large membrane resistance or small internal resistance increases length constant
✔✔Temporal summation: - ✔✔Graded potentials that occur at the same time on a
membrane are summated
✔✔Spatial summation - ✔✔graded potentials that occur at same location and time on
membrane are summated
✔✔Know how graded potentials are summated (temporal & spatial summation) & the
effects of the time & length constants on summation - ✔✔Together spatial and
temporal: influx of Na+ (EPSP) and efflux of K+ are summed if the graded potentials are
temporally and spatially close together
Larger T leads to greater temporal summation of inputs
Larger Lambda leads to greater spatial summation of inputs
✔✔Understand conduction velocity - ✔✔Time and length constants are passive
electrical properties, not affected by voltage gated channels, intrinsic membrane
properties
✔✔Know how an action potential propagated down an axon - ✔✔
✔✔Axon diameter: - ✔✔increases permeability, increases inward current and
decreases resistance
✔✔Myelin - ✔✔Neurons with more myelin can send info faster and over longer
distancesq
✔✔What is saltatory conduction - ✔✔Charging the nearby membrane and opening ion
channels takes time
Action potentials can occur where myelin covers axon
✔✔What are the nodes of Ranvier - ✔✔Gaps are close enough so voltage-sensitive
gates can be triggered on next node
✔✔Be able to describe Otto Loewi's experiment & know its contribution to the
description of synaptic transmission - ✔✔Frog heart experiment, discovered first NT
acetylcholine, signaling across a synapse is chemical
✔✔Know the four steps of neurotransmission (ex. how is neurotransmitter [NT]
synthesized, released & deactivated) - ✔✔Synthesis and stored in axon terminal
Transported to presynaptic membrane and released in response to action potential
Able to activate receptors on postsynaptic membrane
AND ANSWERS GRADED A+
✔✔Nerst potential - ✔✔Equilibrium voltage at which chemical forces balance the
electrical forces, resulting in zero net ionic flow when a single ion species is considered
✔✔How is the resting potential maintained? (How do the ions move across the
membrane & why) - ✔✔There is an ongoing influx of Na+ and a matching efflux of K+
✔✔Know the contribution of Hodgkin & Huxley - ✔✔The axon experimentally to
accurately determine the resting and action potential a
✔✔Understand the Goldman-Hodgkin-Katz (GHK) equation - ✔✔The greater an ions
concentration and permeability, the more it contributes to resting membrane potential
✔✔What is an excitatory postsynaptic potential (EPSP) & how is one produced -
✔✔Brief depolarization of a membrane in response to stimulation, more likely to have
action potential, caused by influx of Na+
✔✔What is an inhibitory postsynaptic potential (IPSP) & how is one produced - ✔✔Brief
hyperpolarization of a membrane in response to stimulation, less likely to fire an action
potential, caused by influx of Cl- and efflux of K+
✔✔How does CTX, TTX & aconitine affect neuron physiology - ✔✔TTX blocks Na+
channels, depolarization, death in 4-6 hours
CTX blocks K+ channels causes hyperexcitability and paralysis
Aconitine: opens Na+ channels, causes death
✔✔Action potential (what ion channels are opened & closed during the phases of an
action potential) - ✔✔Ion channels open during action potential
Na influx, then K efflux
Depolarizing due to Na+ influx (in)
Hyperpolarizing due to K+ efflux (out)
✔✔Relative refractory period - ✔✔Later phase during which increased electrical current
is required to produce another action potential (open K+ channels, oppose Na+ current)
✔✔absolute refractory period - ✔✔During depolarizing and repolarizing period action
potential cannot be produced (Na+ channels recover)
✔✔Time constant - ✔✔Small membrane resistance decreases time constant
Large membrane resistance increases the time constant
Higher the permeability the lower the resistance
, ✔✔Length constant: - ✔✔small membrane resistance or large internal resistance
decreases length constant
Large membrane resistance or small internal resistance increases length constant
✔✔Temporal summation: - ✔✔Graded potentials that occur at the same time on a
membrane are summated
✔✔Spatial summation - ✔✔graded potentials that occur at same location and time on
membrane are summated
✔✔Know how graded potentials are summated (temporal & spatial summation) & the
effects of the time & length constants on summation - ✔✔Together spatial and
temporal: influx of Na+ (EPSP) and efflux of K+ are summed if the graded potentials are
temporally and spatially close together
Larger T leads to greater temporal summation of inputs
Larger Lambda leads to greater spatial summation of inputs
✔✔Understand conduction velocity - ✔✔Time and length constants are passive
electrical properties, not affected by voltage gated channels, intrinsic membrane
properties
✔✔Know how an action potential propagated down an axon - ✔✔
✔✔Axon diameter: - ✔✔increases permeability, increases inward current and
decreases resistance
✔✔Myelin - ✔✔Neurons with more myelin can send info faster and over longer
distancesq
✔✔What is saltatory conduction - ✔✔Charging the nearby membrane and opening ion
channels takes time
Action potentials can occur where myelin covers axon
✔✔What are the nodes of Ranvier - ✔✔Gaps are close enough so voltage-sensitive
gates can be triggered on next node
✔✔Be able to describe Otto Loewi's experiment & know its contribution to the
description of synaptic transmission - ✔✔Frog heart experiment, discovered first NT
acetylcholine, signaling across a synapse is chemical
✔✔Know the four steps of neurotransmission (ex. how is neurotransmitter [NT]
synthesized, released & deactivated) - ✔✔Synthesis and stored in axon terminal
Transported to presynaptic membrane and released in response to action potential
Able to activate receptors on postsynaptic membrane
