Hole's Human Anatomy & Physiology (Shier), 12th Edition

Chapter 9: Muscular System

Chemical Synapse

What are neurotransmitters? Nervous impulses are electrical signals that travel along neurons. The electrical signals cannot travel from one neuron to the next directly. The signal crosses the gap, called a synapse, between cells in chemical form. One neuron releases chemicals in response to an action potential (nerve impulse). The chemicals travel across the synapse and stimulate an action potential in the next neuron. These chemicals are known as neurotransmitters. Neurotransmitters are stored in vesicles within a neuron and released through the arrival of an action potential. They then bind to receptors on the surface of the post-synaptic neuron. There are a wide variety of different kinds of neurotransmitters including amino acids, peptides, and some ions. Different neurotransmitters serve different functions. Acetylcholine is important in the control of voluntary movement while dopamine is important in emotions.

View the animation below, then complete the quiz to test your knowledge of the concept.



1.

An action potential arriving at the presynaptic terminal causes...
A)sodium ions to diffuse into the cell.
B)sodium ions to diffuse out of the cell.
C)calcium ions to diffuse into the cell.
D)acetylcholine to diffuse into the cell.
E)ligand-gated sodium channels to open.
2.

As a result of question number one...
A)synaptic vessels migrate to the plasma membrane and release acetylcholine.
B)acetylcholine is actively transported from the pre-synaptic neuron.
C)acetylcholine is actively transported to the post synaptic neuron.
D)ligand-gated sodium channels open.
E)sodium ions diffuse into the cell.
3.

Acetylcholine has which effect on the post-synaptic neuron?
A)Ligand gated calcium channels open and calcium diffuses in.
B)Ligand gated sodium channels open and sodium diffuses in.
C)Terminal vessels migrate to the plasma membrane.
D)Voltage gated calcium ion channels open and calcium diffuses in.
E)Voltage gated sodium ion channels open and sodium diffuses in.
4.

If the post-synaptic membrane potential reaches threshold level, an action potential will be produced.
A)True
B)False
5.

Acetylcholine is actively transported from the pre-synaptic membrane to the post - synaptic membrane.
A)True
B)False
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