Question 1

Which of the following best describes the difference between an excitatory postsynaptic potential (EPSP) and an inhibitory postsynaptic potential (IPSP)?

Accepted Answer

EPSPs depolarize the postsynaptic membrane by allowing Na+ influx, while IPSPs hyperpolarize it by allowing K+ efflux or Cl- influx.

Question 2

A neuron receives simultaneous input from multiple presynaptic terminals at different locations. What type of summation is occurring?

Accepted Answer

Spatial summation

Question 3

Which ion movement is primarily responsible for the depolarization phase of an EPSP?

Accepted Answer

Na+ influx

Question 4

Why do postsynaptic potentials decay over distance, unlike action potentials?

Accepted Answer

Postsynaptic membranes lack voltage-gated channels, so the signal is not self-amplifying.

Question 5

A patient is experiencing muscle rigidity due to the inhibition of GABA and glycine release. What is the most likely diagnosis?

Accepted Answer

Tetanus

Question 6

Which neurotransmitter is excitatory at skeletal muscle neuromuscular junctions but inhibitory in cardiac muscle?

Accepted Answer

Acetylcholine (ACh)

Question 7

Which of the following equations best represents the synthesis of acetylcholine (ACh)?

Accepted Answer

$\mathrm{Acetyl\ CoA} + \mathrm{Choline} \xrightarrow{\mathrm{Choline\ acetyltransferase}} \mathrm{ACh}$

Question 8

Which neurotransmitter is typically inhibitory and acts via channel-linked receptors that allow Cl- influx?

Accepted Answer

GABA

Question 9

A neuron is exposed to repeated stimulation, resulting in enhanced excitatory postsynaptic potentials (EPSPs). Which process is most likely occurring?

Accepted Answer

Long-term potentiation (LTP)

Question 10

Which of the following best explains why cyclic AMP (cAMP) is called a 'second messenger'?

Accepted Answer

It relays the message from the original chemical messenger outside the cell to effector molecules inside the cell.

Question 11

Which neurotransmitter is a gas, synthesized on demand, and activates guanylate cyclase to produce cGMP?

Accepted Answer

Nitric oxide (NO)

Question 12

Which of the following is a direct-acting neurotransmitter that binds to and opens ion channels for rapid effects?

Accepted Answer

Amino acids

Question 13

A neuron receives multiple EPSPs and IPSPs at its initial segment. What determines whether an action potential will be generated?

Accepted Answer

The summation of all postsynaptic potentials at the axon's initial segment

Question 14

Which of the following is true regarding presynaptic inhibition?

Accepted Answer

It reduces the amount of neurotransmitter released by the presynaptic neuron.

Question 15

Which neurotransmitter is classified as a purine and acts as a strong inhibitor in the brain, with caffeine acting as a stimulant by blocking its receptors?

Accepted Answer

Adenosine

Question 16

Which of the following best describes the role of neuronal pools in the nervous system?

Accepted Answer

They integrate incoming information from receptors or other pools and forward processed signals to other destinations.

Question 17

Which neurotransmitter is released during stress, labor, or exercise and acts as a natural opiate to reduce pain perception?

Accepted Answer

Endorphins

Question 18

Which of the following is a characteristic of channel-linked (ionotropic) neurotransmitter receptors?

Accepted Answer

They mediate fast, direct changes in membrane potential by opening ion channels.

Question 19

A patient with anxiety disorder is prescribed a medication that enhances GABA neurotransmission. What is the expected effect?

Accepted Answer

Enhanced inhibitory transmission, leading to reduced anxiety symptoms

Question 20

Which of the following neurotransmitters is typically excitatory and abundant in the CNS, playing a major role in learning and memory?

Accepted Answer

Glutamate

Postsynaptic Potentials: Excitation, Inhibition, and Synaptic Integration

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