Q: Which of the following best describes the role of Ca$^{2+}$ in synaptic transmission at the presynaptic terminal?

Ca$^{2+}$ triggers the fusion of synaptic vesicles with the membrane, allowing neurotransmitter release.

Question 1

Which of the following best describes the role of Ca$^{2+}$ in synaptic transmission at the presynaptic terminal?

Accepted Answer

Ca$^{2+}$ triggers the fusion of synaptic vesicles with the membrane, allowing neurotransmitter release.

Question 2

A neurotransmitter binds to a receptor on the postsynaptic membrane. What determines the specific effect on the postsynaptic cell?

Accepted Answer

The type of neurotransmitter and the specific receptor present.

Question 3

Which statement about graded potentials (GPs) is correct?

Accepted Answer

GPs decay as they travel away from the synapse.

Question 4

A patient has a mutation that causes chemically gated ion channels to remain open even after the neurotransmitter has unbound. What is the most likely effect on the postsynaptic cell?

Accepted Answer

The postsynaptic cell will experience prolonged ion flow, potentially leading to abnormal depolarization or hyperpolarization.

Question 5

Which equation best represents the decay of a graded potential (GP) as it moves along the neuronal membrane?

Accepted Answer

$V(x) = V_0 e^{-x/\lambda}$

Question 6

Which of the following scenarios best illustrates spatial summation?

Accepted Answer

Multiple presynaptic neurons fire at different locations on the postsynaptic neuron simultaneously.

Question 7

If a postsynaptic membrane receives both EPSPs and IPSPs at the same time, what determines whether an action potential will be generated?

Accepted Answer

The sum of all EPSPs and IPSPs at the axon hillock.

Question 8

Which of the following best describes an Excitatory Postsynaptic Potential (EPSP)?

Accepted Answer

A local depolarization that brings the neuron closer to action potential threshold.

Question 9

A rapidly firing presynaptic neuron causes several EPSPs that are close together in time. What is this phenomenon called?

Accepted Answer

Temporal summation

Question 10

Which of the following is true regarding Inhibitory Postsynaptic Potentials (IPSPs)?

Accepted Answer

IPSPs drive the neuron away from the action potential threshold.

Question 11

A neuron receives three EPSPs and two IPSPs at the same time. If the net effect brings the membrane potential to threshold, what will happen?

Accepted Answer

The neuron will fire an action potential.

Question 12

Which of the following is NOT a factor that determines the action of the postsynaptic cell?

Accepted Answer

The number of mitochondria in the presynaptic cell.

Question 13

If the channels on the postsynaptic membrane are not sensitive to changes in membrane potential, what type of channel are they most likely to be?

Accepted Answer

Chemically gated ion channels

Question 14

Which of the following best explains why graded potentials decay with distance?

Accepted Answer

The cytoplasm and membrane resistance cause the signal to lose strength over distance.

Question 15

A postsynaptic cell has multiple receptors for a single neurotransmitter. What is the functional significance of this?

Accepted Answer

Each receptor activates a different ion channel, allowing for diverse responses.

Question 16

Which of the following is a correct statement about the relationship between EPSPs and IPSPs?

Accepted Answer

EPSPs bring the membrane potential closer to threshold, while IPSPs move it further away.

Question 17

Which of the following would most likely increase the likelihood of an action potential in a postsynaptic neuron?

Accepted Answer

A large number of EPSPs summating temporally and spatially.

Question 18

A researcher applies a drug that blocks all chemically gated ion channels on the postsynaptic membrane. What is the most immediate effect?

Accepted Answer

Neurotransmitters will be unable to generate postsynaptic potentials.

Question 19

Which of the following best describes the effect of temporal summation?

Accepted Answer

EPSPs generated close together in time add together to increase the likelihood of reaching threshold.

Synaptic Transmission and Graded Potentials in Neuronal Physiology

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