Q: Which equation correctly represents Ohm's Law as it applies to neurons, and what does each variable represent?

$$V = I \times R$$, where $$V is $$voltage, $$I is $$current, and $$R is $$resistance.

Q: During the repolarization phase of an action potential, which ion movement is primarily responsible for restoring the negative membrane potential?

Potassium ions ($$\text{K}^+) $$leave the cell.

Q: Which of the following would most likely result in an inhibitory postsynaptic potential (IPSP)?

Opening potassium channels, allowing $$\text{K}^+ to $$leave the postsynaptic cell.

Question 1

A neuron at rest has a membrane potential of approximately $$-70\ 	ext{mV}. $$Which of the following best explains why the inside of the neuron is negative relative to the outside?

Accepted Answer

Potassium leaks out of the cell more easily than sodium leaks in, and large negatively charged proteins remain trapped inside.

Question 2

Which equation correctly represents Ohm's Law as it applies to neurons, and what does each variable represent?

Accepted Answer

$$V = I 	imes R$$, where $$V is $$voltage, $$I is $$current, and $$R is $$resistance.

Question 3

A patient is given lidocaine as a local anesthetic. Which step in the action potential is directly blocked by this drug, and what is the physiological consequence?

Accepted Answer

Lidocaine blocks voltage-gated sodium channels, preventing depolarization and inhibiting action potential generation.

Question 4

During the repolarization phase of an action potential, which ion movement is primarily responsible for restoring the negative membrane potential?

Accepted Answer

Potassium ions ($$	ext{K}^+) $$leave the cell.

Question 5

A neuron receives multiple excitatory postsynaptic potentials (EPSPs) from different presynaptic neurons at the same time. What is this process called, and what is its effect?

Accepted Answer

Spatial summation; increases the likelihood of reaching threshold by simultaneous firing from multiple neurons.

Question 6

Which of the following best describes the all-or-none principle of action potentials?

Accepted Answer

Once threshold is reached, a neuron generates a full action potential; if threshold is not reached, no action potential occurs.

Question 7

A patient with Multiple Sclerosis (MS) is experiencing muscle weakness and poor coordination. Which cellular structure is most directly affected in MS, and how does this impact nerve conduction?

Accepted Answer

Oligodendrocytes in the CNS are destroyed, leading to loss of myelin and impaired saltatory conduction.

Question 8

Which of the following is TRUE regarding graded potentials?

Accepted Answer

They are short-lived, localized, and can be either depolarizing or hyperpolarizing.

Question 9

Which sequence correctly describes the steps of neurotransmitter release at a chemical synapse?

Accepted Answer

Action potential arrives → voltage-gated calcium channels open → calcium enters → vesicles fuse with membrane → neurotransmitter released by exocytosis.

Question 10

Which of the following would most likely result in an inhibitory postsynaptic potential (IPSP)?

Accepted Answer

Opening potassium channels, allowing $$	ext{K}^+ to $$leave the postsynaptic cell.

Question 11

A neuron is in the absolute refractory period. What is the state of its voltage-gated sodium channels, and what is the consequence for action potential generation?

Accepted Answer

Voltage-gated sodium channels are open or inactivated; no new action potential can be generated regardless of stimulus strength.

Question 12

Which of the following best explains why saltatory conduction is faster than continuous conduction?

Accepted Answer

Saltatory conduction occurs in myelinated axons, where action potentials 'jump' between Nodes of Ranvier, reducing the amount of membrane that must depolarize.

Question 13

Which neurotransmitter is primarily involved in skeletal muscle contraction, and which disease is associated with loss of its receptors at the neuromuscular junction?

Accepted Answer

Acetylcholine; Myasthenia Gravis

Question 14

A neuron receives both EPSPs and IPSPs. What determines whether it will fire an action potential?

Accepted Answer

The neuron will fire if the sum of EPSPs and IPSPs brings the membrane potential above threshold ($$-55\ 	ext{mV}).$$

Question 15

Which process is responsible for removing acetylcholine from the synaptic cleft after it has been released?

Accepted Answer

Enzymatic breakdown by acetylcholinesterase

Question 16

Which of the following best describes the effect of opening voltage-gated sodium channels during the depolarization phase of an action potential?

Accepted Answer

Sodium ions ($$	ext{Na}^+) $$enter the cell, making the inside more positive.

Question 17

Which type of ion channel is responsible for generating graded potentials in response to neurotransmitter binding?

Accepted Answer

Chemically gated (ligand-gated) channels

Question 18

A neuron is exposed to tetrodotoxin (TTX) from pufferfish. What is the most immediate effect on neuronal function?

Accepted Answer

TTX blocks voltage-gated sodium channels, preventing action potential generation and leading to paralysis.

Question 19

Which of the following is a key difference between electrical and chemical synapses?

Accepted Answer

Electrical synapses are faster and often bidirectional, while chemical synapses are slower and typically one-way.

Chapter 11: Fundamentals of the Nervous System and Nervous Tissue – Membrane Potentials, Action Potentials, and Synaptic Transmission

Study Guide - Practice Questions

Study Guide - Flashcards