Q: During the generation of an action potential, which event occurs immediately after the membrane depolarizes to threshold?

Sodium channels open, allowing Na\textsuperscript{+} to enter the cell.

Q: Which equation correctly represents the Nernst equation for calculating the equilibrium potential of an ion?

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

Question 1

Which of the following best describes the role of acetylcholine (ACh) at a cholinergic synapse?

Accepted Answer

ACh binds to receptors on the postsynaptic membrane, directly opening ion channels and causing rapid depolarization.

Question 2

During the generation of an action potential, which event occurs immediately after the membrane depolarizes to threshold?

Accepted Answer

Sodium channels open, allowing Na	extsuperscript{+} to enter the cell.

Question 3

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

Accepted Answer

$$E = \frac{RT}{zF} \ln \left( \frac{[	ext{ion}]_{	ext{out}}}{[	ext{ion}]_{	ext{in}}} ight)$$

Question 4

A patient is exposed to a toxin that blocks voltage-gated sodium channels. What is the most likely effect on neuronal signaling?

Accepted Answer

Action potentials will fail to initiate and propagate.

Question 5

Which of the following best explains the difference between direct and indirect neurotransmitter effects on membrane potential?

Accepted Answer

Direct effects involve neurotransmitter binding that opens or closes ion channels, while indirect effects involve activation of second messenger pathways.

Question 6

Which structure is responsible for the breakdown of acetylcholine in the synaptic cleft?

Accepted Answer

Acetylcholinesterase

Question 7

A drug that inhibits acetylcholinesterase would most likely cause which effect at a cholinergic synapse?

Accepted Answer

Prolonged activation of postsynaptic receptors due to increased ACh in the synaptic cleft

Question 8

Which of the following is a correct sequence of events in the generation of an action potential?

Accepted Answer

Depolarization to threshold → Activation of sodium channels → Inactivation of sodium channels and activation of potassium channels → Return to normal permeability

Question 9

Which part of the nervous system is responsible for voluntary control of skeletal muscles?

Accepted Answer

Somatic nervous system

Question 10

Which of the following best describes the function of myelin in the nervous system?

Accepted Answer

Myelin increases the speed of action potential propagation by insulating axons.

Question 11

Which equation represents the Goldman-Hodgkin-Katz (GHK) equation for membrane potential?

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 12

A patient presents with muscle weakness and fatigue. Laboratory tests reveal antibodies against acetylcholine receptors. Which condition is most likely?

Accepted Answer

Myasthenia gravis

Question 13

Which of the following is NOT a function of astrocytes in the central nervous system?

Accepted Answer

Producing myelin

Question 14

Which neurotransmitter is primarily involved in the sympathetic division of the autonomic nervous system?

Accepted Answer

Norepinephrine

Question 15

Which of the following best describes saltatory conduction?

Accepted Answer

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

Question 16

Which of the following is a correct description of the absolute refractory period?

Accepted Answer

A period during which no action potential can be generated, regardless of stimulus strength.

Question 17

Which of the following is a function of microglia in the central nervous system?

Accepted Answer

Phagocytosis of cellular debris and pathogens

Question 18

Which ion is primarily responsible for the repolarization phase of the action potential?

Accepted Answer

Potassium (K	extsuperscript{+})

Question 19

A patient is given a drug that increases cAMP levels in postsynaptic neurons. Which type of neurotransmitter effect is this most likely to enhance?

Accepted Answer

Indirect effect via second messenger pathways

Nervous Tissue: Structure, Function, and Synaptic Transmission

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