Question 1

Which equation would you use to calculate the equilibrium potential for potassium ($$K^+) $$across a neuronal membrane, and what is the main variable that determines its value?

Accepted Answer

The Nernst equation; the concentration gradient of $$K^+$$

Question 2

A patient presents with hyperkalemia (elevated blood $$K^+). $$How does this affect the resting membrane potential and neuronal excitability?

Accepted Answer

The membrane potential becomes less negative, making neurons more excitable

Question 3

Which of the following best describes the difference between graded potentials and action potentials in neurons?

Accepted Answer

Graded potentials can sum and vary in amplitude, while action potentials are all-or-none and cannot sum

Question 4

Which ion channel state is responsible for the absolute refractory period during an action potential?

Accepted Answer

Voltage-gated $$Na^+$$ channels are inactivated

Question 5

A neuron receives a subthreshold graded potential at the dendrite. What is the most likely outcome at the axon hillock?

Accepted Answer

No action potential will be generated

Question 6

Which of the following best explains why myelinated axons conduct action potentials faster than unmyelinated axons?

Accepted Answer

Myelin increases membrane resistance and enables saltatory conduction

Question 7

Which formula correctly represents Ohm’s Law as it applies to ion flow across a neuronal membrane?

Accepted Answer

$$V = I 	imes R$$

Question 8

During the rising phase of the action potential, which event occurs first?

Accepted Answer

Voltage-gated $$Na^+$$ channels open, allowing $$Na^+$$ influx

Question 9

A demyelinating disease such as multiple sclerosis affects nerve conduction by:

Accepted Answer

Increasing current leak and slowing or blocking action potential conduction

Question 10

Which of the following scenarios would most likely result in a neuron firing an action potential?

Accepted Answer

A suprathreshold graded potential that reaches the trigger zone

Question 11

Which of the following is a correct application of the Goldman-Hodgkin-Katz (GHK) equation for membrane potential?

Accepted Answer

It predicts membrane potential based on the permeability and concentration gradients of multiple ions

Question 12

Which process is responsible for the termination of neurotransmitter activity in the synaptic cleft?

Accepted Answer

Enzymatic breakdown, reuptake into cells, or diffusion away

Question 13

If a neuron is exposed to hypokalemia (low extracellular $$K^+$$), what is the expected effect on the resting membrane potential and excitability?

Accepted Answer

The membrane potential becomes more negative and the neuron is less excitable

Question 14

Which of the following best describes the sequence of events for neurotransmitter release at a chemical synapse?

Accepted Answer

Action potential arrives, voltage-gated $$Ca^{2+}$$ channels open, $$Ca^{2+}$$ influx, vesicle exocytosis

Question 15

A neuron’s action potential is initiated at the axon hillock. What property of the action potential ensures that it travels in only one direction down the axon?

Accepted Answer

The refractory period due to inactivation of $$Na^+$$ channels

Question 16

Which of the following would increase the speed of action potential conduction in a neuron?

Accepted Answer

Increasing axon diameter and adding myelin

Question 17

Which of the following is true regarding the coding of stimulus strength in neurons?

Accepted Answer

Stronger stimuli increase the frequency of action potentials

Question 18

Which of the following best explains why graded potentials decrease in strength as they move away from the point of origin?

Accepted Answer

Due to current leak and cytoplasmic resistance

Question 19

Which of the following is a real-life consequence of a prolonged absolute refractory period in cardiac muscle cells?

Accepted Answer

It prevents tetanus, ensuring the heart can relax between beats

Neurons: Cellular and Network Properties – Study Notes for Anatomy & Physiology

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