Question 1

During the absolute refractory period of an action potential, which of the following best explains why a neuron cannot fire another action potential, regardless of stimulus strength?

Accepted Answer

Voltage-gated Na$$^+$$ channels are inactivated and cannot reopen until the membrane potential returns to resting levels.

Question 2

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

Accepted Answer

Graded potentials can summate and vary in amplitude, while action potentials are all-or-none and have a fixed amplitude.

Question 3

A patient is given a drug that increases the permeability of the neuronal membrane to K$$^+. $$What effect would this have on the excitability of the neuron?

Accepted Answer

It would decrease excitability by hyperpolarizing the membrane, making it harder to reach threshold.

Question 4

Which of the following equations correctly represents the Nernst equation for calculating the equilibrium potential of an ion?

Accepted Answer

$$E_{ion} = \frac{RT}{zF} \ln \left( \frac{[ion]_{out}}{[ion]_{in}} \right)$$

Question 5

Which of the following statements about saltatory conduction is correct?

Accepted Answer

Action potentials jump from one node of Ranvier to the next, increasing conduction velocity.

Question 6

If a neuron receives both excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs) at the same time, what determines whether it will fire an action potential?

Accepted Answer

The net effect of EPSPs and IPSPs at the axon hillock determines if the membrane potential reaches threshold.

Question 7

Which of the following best describes the role of voltage-gated Ca$$^{2+}$$ channels in chemical synaptic transmission?

Accepted Answer

They open in response to depolarization, allowing Ca$$^{2+}$$ influx that triggers neurotransmitter release.

Question 8

Which of the following is a correct sequence of events at a chemical synapse?

Accepted Answer

Action potential arrives at axon terminal → voltage-gated Ca$$^{2+}$$ channels open → Ca$$^{2+}$$ enters → neurotransmitter vesicles fuse with membrane → neurotransmitter released into synaptic cleft.

Question 9

Which of the following best describes an ionotropic receptor?

Accepted Answer

A receptor that is a ligand-gated ion channel, producing a rapid cellular response.

Question 10

A patient has a mutation that prevents the formation of myelin in the central nervous system. Which of the following symptoms would most likely result?

Accepted Answer

Slower action potential conduction and impaired coordination.

Question 11

Which of the following is NOT a component of a typical reflex arc?

Accepted Answer

Cerebral cortex

Question 12

Which equation would you use to calculate the membrane potential when multiple ions are permeable, such as Na$$^+$$, K$$^+$$, and Cl$$^-$$?

Accepted Answer

$$V_m = \frac{RT}{F} \ln \left( \frac{P_{K^+}[K^+]_{out} + P_{Na^+}[Na^+]_{out} + P_{Cl^-}[Cl^-]_{in}}{P_{K^+}[K^+]_{in} + P_{Na^+}[Na^+]_{in} + P_{Cl^-}[Cl^-]_{out}} \right)$$

Question 13

Which of the following best explains why EPSPs and IPSPs are graded potentials?

Accepted Answer

Their amplitude depends on the amount of neurotransmitter released and the number of receptors activated.

Question 14

Which of the following is a correct pairing of nervous system division and its function?

Accepted Answer

Efferent division: carries motor commands from the CNS to effectors.

Question 15

A person touches a hot stove and quickly withdraws their hand. Which of the following best describes the pathway involved?

Accepted Answer

Sensory receptor → sensory neuron → integration center → motor neuron → effector

Question 16

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

Accepted Answer

Increasing axon diameter and adding myelin sheaths.

Question 17

Which of the following best describes the effect of opening ligand-gated Cl$$^-$$ channels on a postsynaptic neuron?

Accepted Answer

It causes an IPSP by hyperpolarizing the membrane.

Question 18

Which of the following is true regarding the threshold for action potential generation?

Accepted Answer

It is the membrane potential at which voltage-gated Na$$^+$$ channels open rapidly, initiating an action potential.

Question 19

Which of the following best explains why action potentials are unidirectional along an axon?

Accepted Answer

The refractory period prevents the action potential from traveling backward.

Anatomy & Physiology: Neuronal Signaling, Synapses, and Reflex Pathways Study Guide

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