Question 1

A neuron is exposed to a toxin that blocks voltage-gated sodium channels. Which phase of the action potential would be directly prevented by this toxin?

Accepted Answer

Depolarization

Question 2

Which equation correctly describes the relationship between current ($$I$$), voltage ($$V$$), and resistance ($$R) in $$biological membranes?

Accepted Answer

$$I = \frac{V}{R}$$

Question 3

A patient has a genetic mutation that causes their neurons to have fewer leak potassium channels. What is the most likely effect on their resting membrane potential?

Accepted Answer

The resting membrane potential would become less negative (closer to zero).

Question 4

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

Accepted Answer

Graded potentials decay with distance, while action potentials do not.

Question 5

During which period can a neuron generate another action potential only if the stimulus is stronger than usual?

Accepted Answer

Relative refractory period

Question 6

A myelinated axon is damaged, resulting in the loss of myelin. Which of the following best describes the effect on action potential conduction?

Accepted Answer

Conduction velocity decreases due to loss of saltatory conduction.

Question 7

Which type of membrane ion channel opens in response to a neurotransmitter binding to its receptor?

Accepted Answer

Chemically gated channel

Question 8

At a chemical synapse, which ion's influx into the presynaptic terminal directly triggers neurotransmitter release?

Accepted Answer

Calcium ($$\mathrm{Ca}^{2+})$$

Question 9

Which of the following neurotransmitters is classified as a biogenic amine and is involved in mood regulation?

Accepted Answer

Serotonin

Question 10

A postsynaptic neuron receives two excitatory postsynaptic potentials (EPSPs) in rapid succession from the same presynaptic neuron. This is an example of:

Accepted Answer

Temporal summation

Question 11

Which of the following best explains why action potentials are considered 'all-or-none' events?

Accepted Answer

Once threshold is reached, an action potential of fixed size is generated.

Question 12

Which of the following is a direct effect of an inhibitory postsynaptic potential (IPSP) on the postsynaptic neuron?

Accepted Answer

Hyperpolarization of the membrane

Question 13

Which of the following is TRUE regarding the Na⁺/K⁺ pump in neurons?

Accepted Answer

It moves 3 Na⁺ out and 2 K⁺ in, maintaining the resting membrane potential.

Question 14

Which of the following best describes the main structural difference between chemical and electrical synapses?

Accepted Answer

Chemical synapses have a synaptic cleft, while electrical synapses have gap junctions.

Question 15

A neuron receives both EPSPs and IPSPs at the same time from different presynaptic neurons. What is the outcome called when these signals combine to influence the postsynaptic membrane potential?

Accepted Answer

Spatial summation

Question 16

Which of the following neurotransmitters is most directly involved in skeletal muscle contraction?

Accepted Answer

Acetylcholine

Question 17

Which of the following would most likely increase the speed of action potential conduction along an axon?

Accepted Answer

Increasing axon diameter

Question 18

Which of the following best describes the effect of synaptic potentiation?

Accepted Answer

Repeated stimulation leads to stronger postsynaptic responses.

Question 19

Which type of receptor is associated with fast, direct opening of ion channels in response to neurotransmitter binding?

Accepted Answer

Channel-linked (ligand-gated) receptor

Question 20

A patient is exposed to a drug that increases the activity of GABA in the brain. What is the most likely effect on neuronal activity?

Accepted Answer

Neuronal activity decreases due to increased inhibition.

Chapter 11: Bioelectricity and Fundamentals of the Nervous System

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