Q: Which of the following best explains how an IPSP is generated?

Opening of ligand-gated potassium channels causing K\textsuperscript{+} efflux or chloride channels causing Cl\textsuperscript{–} influx

Q: Which of the following equations best represents the summation of postsynaptic potentials at the trigger zone?

$$V_{m,\text{final}} = V_{m,\text{rest}} + \sum \text{EPSPs} - \sum \text{IPSPs}$$

Question 1

Which of the following best describes an axodendritic synapse?

Accepted Answer

A synapse where the axon of one neuron connects to the dendrite of another neuron

Question 2

What is the primary function of synaptic transmission in the nervous system?

Accepted Answer

To transfer chemical or electrical signals between neurons at a synapse

Question 3

A postsynaptic potential that brings the membrane potential closer to threshold is called:

Accepted Answer

Excitatory Postsynaptic Potential (EPSP)

Question 4

Which ion movement is most directly responsible for generating an EPSP?

Accepted Answer

Opening of ligand-gated sodium or calcium channels allowing Na	extsuperscript{+} or Ca	extsuperscript{2+} to enter the cell

Question 5

Which of the following best explains how an IPSP is generated?

Accepted Answer

Opening of ligand-gated potassium channels causing K	extsuperscript{+} efflux or chloride channels causing Cl	extsuperscript{–} influx

Question 6

A neuron receives input from several presynaptic neurons at the same time, each releasing neurotransmitter. This is an example of:

Accepted Answer

Spatial summation

Question 7

If a single presynaptic neuron fires rapidly and repeatedly, causing multiple EPSPs in a short period, what process is occurring?

Accepted Answer

Temporal summation

Question 8

Which of the following is NOT a method for terminating synaptic transmission?

Accepted Answer

Continuous stimulation of the postsynaptic neuron

Question 9

A patient is given a drug that inhibits the enzyme responsible for neurotransmitter degradation in the synaptic cleft. What is the most likely effect on synaptic transmission?

Accepted Answer

Neurotransmitter will remain in the synaptic cleft longer, prolonging the postsynaptic response

Question 10

Which of the following best describes neural integration?

Accepted Answer

The process by which all input from presynaptic neurons is combined to have a cumulative effect on the postsynaptic neuron

Question 11

If a postsynaptic neuron receives both EPSPs and IPSPs simultaneously, what determines whether it will fire an action potential?

Accepted Answer

The sum of all EPSPs and IPSPs at the trigger zone

Question 12

Which of the following equations best represents the summation of postsynaptic potentials at the trigger zone?

Accepted Answer

$$V_{m,	ext{final}} = V_{m,	ext{rest}} + \sum 	ext{EPSPs} - \sum 	ext{IPSPs}$$

Question 13

A neuron is exposed to a toxin that blocks ligand-gated sodium channels. What is the most likely effect on synaptic transmission?

Accepted Answer

EPSPs will be reduced or absent, making it less likely for the neuron to reach threshold

Question 14

Which of the following scenarios would most likely result in a postsynaptic neuron being slightly hyperpolarized?

Accepted Answer

Simultaneous summation of EPSPs and IPSPs with IPSPs slightly outweighing EPSPs

Question 15

Which structural type of synapse is most likely to have a direct effect on the action potential initiation at the axon hillock?

Accepted Answer

Axosomatic synapse

Question 16

A patient has a genetic mutation that impairs the reuptake of neurotransmitters into the presynaptic neuron. Which of the following is a likely consequence?

Accepted Answer

Prolonged presence of neurotransmitter in the synaptic cleft

Question 17

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

Accepted Answer

Chemical synapses use neurotransmitters, while electrical synapses use gap junctions for direct ion flow

Question 18

If the average presynaptic neuron forms synapses with about 1,000 postsynaptic neurons, and each postsynaptic neuron receives input from up to 10,000 presynaptic neurons, what does this suggest about neural networks in the CNS?

Accepted Answer

Neural networks are highly interconnected and complex

Neuronal Synapses: Structure, Function, and Synaptic Potentials - 11.4

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