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Ch. 11 Introduction to the Nervous System and Nervous Tissue
All textbooksErin C. Amerman 2nd EditionCh. 11 Introduction to the Nervous System and Nervous TissueProblem 11.10a
Chapter 11, Problem 11.10a

The trigger for exocytosis of synaptic vesicles from the presynaptic neuron is:


a. arrival of an action potential at the axon terminal and influx of calcium ions.
b. summation of IPSPs at the presynaptic neuron.
c. binding of neurotransmitters to the axon hillock.
d. influx of Na+ into the postsynaptic neuron.

Verified step by step guidance
1
Identify the process of exocytosis in neurons, which involves the release of neurotransmitters from synaptic vesicles into the synaptic cleft.
Understand that exocytosis is triggered by specific events at the presynaptic neuron.
Recall that the arrival of an action potential at the axon terminal is a key event in neuronal communication.
Recognize that the influx of calcium ions (Ca²⁺) into the presynaptic neuron is crucial for the fusion of synaptic vesicles with the presynaptic membrane.
Determine which option describes the correct sequence of events leading to exocytosis: the arrival of an action potential and the influx of calcium ions.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Exocytosis

Exocytosis is a cellular process where vesicles fuse with the plasma membrane to release their contents outside the cell. In the context of neurons, synaptic vesicles containing neurotransmitters undergo exocytosis when triggered, allowing communication between neurons. This process is essential for neurotransmission and occurs at the axon terminal.
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Endocytosis and Exocytosis

Action Potential

An action potential is a rapid, temporary change in the membrane potential of a neuron, which occurs when a stimulus causes depolarization. This electrical signal travels along the axon to the axon terminal, where it triggers the opening of voltage-gated calcium channels, leading to the influx of calcium ions that initiate exocytosis of neurotransmitters.
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Action Potential

Calcium Ions (Ca2+)

Calcium ions play a crucial role in neurotransmitter release during synaptic transmission. When an action potential reaches the axon terminal, voltage-gated calcium channels open, allowing Ca2+ to flow into the neuron. The increase in intracellular calcium concentration is the key signal that triggers the fusion of synaptic vesicles with the membrane, resulting in exocytosis.
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Ions - Sodium and Potassium Example 3
Related Practice
Textbook Question

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.


c. The Na+/K+ pumps and gated channels maintain the Na+ and K+ gradients necessary for action potentials to occur.

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Textbook Question

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.


d. A depolarization is a change in membrane potential that makes the potential less negative.

435
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Textbook Question

Describe the three components of the neuromuscular junction.

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Textbook Question

A drug that blocks Na+ channels in neurons does so not only in the axon but also in the dendrites and cell body. What overall effect would this have on action potential generation?

379
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Textbook Question

The d​​rug neostigmine blocks the actions of acetylcholinesterase in the synaptic cleft. What effect would this have on synaptic transmission? What effects might you expect to see as a result of this drug?

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Textbook Question

Which of the following is not a method by which the effects of neurotransmitters are terminated?​​


a. Reuptake into the presynaptic neuron

b. Diffusion away from the synaptic cleft and uptake by glial cells

c. Movement back to the cell body by retrograde axonal transport

d. Degradation by enzymes in the synaptic cleft

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