CLINICAL NEUROSCIENCE (CLARK) EXAM 1 QUESTIONS AND
ANSWERS 2024/2025 UPDATED A COMPLETE SOLUTION ALL
ANSWERS 100% CORRECT DETAILED BEST GRADED A+ FOR
SUCCESS
Temporal Summation - CORRECT ANSWERS ○integration of events happening at
different times
○trigger the same receptor multiple times
○doesn't cancel, usually just adds PSPs that are the same
○possible combinations:
1.) two EPSPs elicited in rapid succession sum to produce a larger EPSP
2.) two IPSPs elicited in rapid succession sum to produce a larger IPSP
Action Potentials (APs) - CORRECT ANSWERS ○non-decremental because they use ATP
to activate
○ conducted slower than PSPs
○passive and active (uses ATP)
○a new AP is actively generated at each Node of Ranvier
○moves like a wave down the axon from node to node
Voltage Clamp Method - CORRECT ANSWERS ○tells you the current when connected
to an axon (used squid axon for model)
○controls (clamps) membrane potential
○one electrode adds or inhibits currents and another electrode passively measures the current
(shows APs)
○current equals membrane potential, which allows you to measure ionic flow (where Na+ and
K+ are going)
○negative feedback loop
Hodgkin-Huxley Model - CORRECT ANSWERS states that membrane permeability
changes depending on how polarized the membrane is and differing voltages
,CLINICAL NEUROSCIENCE (CLARK) EXAM 1 QUESTIONS AND
ANSWERS 2024/2025 UPDATED A COMPLETE SOLUTION ALL
ANSWERS 100% CORRECT DETAILED BEST GRADED A+ FOR
SUCCESS
Hodgkin-Huxley Model: Hyperpolarization (current) - CORRECT ANSWERS ○capacitive
current
○cell getting back to resting potential
brief change
Hodgkin-Huxley Model: Depolarization (current) - CORRECT ANSWERS ○first,
capacitive current
○then transient inward current
○followed by delayed outward current
Early Current - CORRECT ANSWERS ○in depolarization, the current that initially gets
larger, then decreases with further depolarization
○with more depolarization, current decreases and switches direction because concentration
gradient of K+ is slowly moved across cell
○reverses when Na+ is the charge carrier
Late Current - CORRECT ANSWERS ○in depolarization, the current that increases
monotonically with depolarization
○keeps increasing steadily with more depolarization because concentration gradient of Na+
moves quickly in/out of cell
○reverses when K+ is the charge carrier
Hodgkin-Huxley Conclusions - CORRECT ANSWERS ○Na+ and K+ conductances change
over time, require time to activate, and Na+ conductance also inactivated
○both Na+ and K+ conductances are voltage-dependent
, CLINICAL NEUROSCIENCE (CLARK) EXAM 1 QUESTIONS AND
ANSWERS 2024/2025 UPDATED A COMPLETE SOLUTION ALL
ANSWERS 100% CORRECT DETAILED BEST GRADED A+ FOR
SUCCESS
○Depolarization occurs because of activation of Na+ and K+ conductances and inactivation of
Na+ conductances
Hodgkin-Huxley Predictions - CORRECT ANSWERS 1.) ions have to be able to more
quickly
2.) channels have to make use of electrochemical gradients
3.) channels must discriminate between Na+ and K+
4.) channels must sense and respond to voltage change (must be voltage-sensitive and ion
selective channels)
Patch Clamp Method - CORRECT ANSWERS ○used to see how cells are affected by
voltage and how they behave at different voltages
○follow single channels through a membrane
○micropipet is used to record voltage and can adjust the voltage
Tetrodotoxin (TTX) - CORRECT ANSWERS ○ alkyloid toxin isolated from puffer fish
○ blocks the early (inward) current (Na+ channel)
○ is a selective blocker of voltage gated Na+ channels
○produces paralysis
Tetraethylammonium (TEA) - CORRECT ANSWERS ○blocks the late (outward) current
(K+ channel)
○is a selective blocker of voltage-gated K+ channels
○causes repeated firing of neurons (tremors, epilepsy)
ANSWERS 2024/2025 UPDATED A COMPLETE SOLUTION ALL
ANSWERS 100% CORRECT DETAILED BEST GRADED A+ FOR
SUCCESS
Temporal Summation - CORRECT ANSWERS ○integration of events happening at
different times
○trigger the same receptor multiple times
○doesn't cancel, usually just adds PSPs that are the same
○possible combinations:
1.) two EPSPs elicited in rapid succession sum to produce a larger EPSP
2.) two IPSPs elicited in rapid succession sum to produce a larger IPSP
Action Potentials (APs) - CORRECT ANSWERS ○non-decremental because they use ATP
to activate
○ conducted slower than PSPs
○passive and active (uses ATP)
○a new AP is actively generated at each Node of Ranvier
○moves like a wave down the axon from node to node
Voltage Clamp Method - CORRECT ANSWERS ○tells you the current when connected
to an axon (used squid axon for model)
○controls (clamps) membrane potential
○one electrode adds or inhibits currents and another electrode passively measures the current
(shows APs)
○current equals membrane potential, which allows you to measure ionic flow (where Na+ and
K+ are going)
○negative feedback loop
Hodgkin-Huxley Model - CORRECT ANSWERS states that membrane permeability
changes depending on how polarized the membrane is and differing voltages
,CLINICAL NEUROSCIENCE (CLARK) EXAM 1 QUESTIONS AND
ANSWERS 2024/2025 UPDATED A COMPLETE SOLUTION ALL
ANSWERS 100% CORRECT DETAILED BEST GRADED A+ FOR
SUCCESS
Hodgkin-Huxley Model: Hyperpolarization (current) - CORRECT ANSWERS ○capacitive
current
○cell getting back to resting potential
brief change
Hodgkin-Huxley Model: Depolarization (current) - CORRECT ANSWERS ○first,
capacitive current
○then transient inward current
○followed by delayed outward current
Early Current - CORRECT ANSWERS ○in depolarization, the current that initially gets
larger, then decreases with further depolarization
○with more depolarization, current decreases and switches direction because concentration
gradient of K+ is slowly moved across cell
○reverses when Na+ is the charge carrier
Late Current - CORRECT ANSWERS ○in depolarization, the current that increases
monotonically with depolarization
○keeps increasing steadily with more depolarization because concentration gradient of Na+
moves quickly in/out of cell
○reverses when K+ is the charge carrier
Hodgkin-Huxley Conclusions - CORRECT ANSWERS ○Na+ and K+ conductances change
over time, require time to activate, and Na+ conductance also inactivated
○both Na+ and K+ conductances are voltage-dependent
, CLINICAL NEUROSCIENCE (CLARK) EXAM 1 QUESTIONS AND
ANSWERS 2024/2025 UPDATED A COMPLETE SOLUTION ALL
ANSWERS 100% CORRECT DETAILED BEST GRADED A+ FOR
SUCCESS
○Depolarization occurs because of activation of Na+ and K+ conductances and inactivation of
Na+ conductances
Hodgkin-Huxley Predictions - CORRECT ANSWERS 1.) ions have to be able to more
quickly
2.) channels have to make use of electrochemical gradients
3.) channels must discriminate between Na+ and K+
4.) channels must sense and respond to voltage change (must be voltage-sensitive and ion
selective channels)
Patch Clamp Method - CORRECT ANSWERS ○used to see how cells are affected by
voltage and how they behave at different voltages
○follow single channels through a membrane
○micropipet is used to record voltage and can adjust the voltage
Tetrodotoxin (TTX) - CORRECT ANSWERS ○ alkyloid toxin isolated from puffer fish
○ blocks the early (inward) current (Na+ channel)
○ is a selective blocker of voltage gated Na+ channels
○produces paralysis
Tetraethylammonium (TEA) - CORRECT ANSWERS ○blocks the late (outward) current
(K+ channel)
○is a selective blocker of voltage-gated K+ channels
○causes repeated firing of neurons (tremors, epilepsy)
