PCB4843 Week 3 - Questions with Correct Answers
(Verified Update)
55 questions with answers
Topic: PCB4843 Week 3
1. voltage clamp technique
Answer: fixes voltage by injecting currents
2. when does resting potential equal equilibrium potential
Answer: when a neuron's membrane is only permeable to one ion
3. command voltage
Answer: the defined parameter in the voltage clamp technique
4. importance of the squid giant axon
Answer: helped prove that action potentials occur due to Na+ and K+ changing
concentration
5. transient inward current
Answer: due to Na+
6. delayed outward current
Answer: due to K+
7. what happens when you experimentally hyperpolarize a squid neuron
Answer: nothing
8. what happens when you experimentally depolarize a squid neuron
Answer: an action potential occurs with transient inward and delayed outward currents
9. voltage clamping at 52mV
Answer: transient inward current (early component) disappears because 52 mV is around
the ENa+
10. voltage clamping above 52mV
Answer: transient inward current (early component) becomes an outward current
11. removing extracellular Na+
Answer: Na+ goes out of the cell instead of inward because of the concentration gradient
12. reducing extracellular Na+
Answer: ENa+ is lowered, so equilibrium is reached at a lower voltage
13. TTX
Answer: blocks Na+ channels, so no transient inward current is observed
14. TEA
Answer: blocks K+ channels, so no delayed outward current is observed
15. what do voltage clamp and pharmacological experiments collectively prove
Answer: that Na+ is responsible for the early current and K+ is responsible for the late
current
Page 1
(Verified Update)
55 questions with answers
Topic: PCB4843 Week 3
1. voltage clamp technique
Answer: fixes voltage by injecting currents
2. when does resting potential equal equilibrium potential
Answer: when a neuron's membrane is only permeable to one ion
3. command voltage
Answer: the defined parameter in the voltage clamp technique
4. importance of the squid giant axon
Answer: helped prove that action potentials occur due to Na+ and K+ changing
concentration
5. transient inward current
Answer: due to Na+
6. delayed outward current
Answer: due to K+
7. what happens when you experimentally hyperpolarize a squid neuron
Answer: nothing
8. what happens when you experimentally depolarize a squid neuron
Answer: an action potential occurs with transient inward and delayed outward currents
9. voltage clamping at 52mV
Answer: transient inward current (early component) disappears because 52 mV is around
the ENa+
10. voltage clamping above 52mV
Answer: transient inward current (early component) becomes an outward current
11. removing extracellular Na+
Answer: Na+ goes out of the cell instead of inward because of the concentration gradient
12. reducing extracellular Na+
Answer: ENa+ is lowered, so equilibrium is reached at a lower voltage
13. TTX
Answer: blocks Na+ channels, so no transient inward current is observed
14. TEA
Answer: blocks K+ channels, so no delayed outward current is observed
15. what do voltage clamp and pharmacological experiments collectively prove
Answer: that Na+ is responsible for the early current and K+ is responsible for the late
current
Page 1
