Questions and Answers
What is an example of a presynaptic cell?
a neuron
Which component has a role in the postsynaptic cell during synaptic activity?
chemically gated channels
What is the role of calcium in synaptic activity?
Calcium influx into the synaptic terminal causes vesicle fusion.
What is the direct role of neurotransmitter at a chemical synapse?
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Neurotransmitter is released from presynaptic neurons through what mechanism?
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What type of channel on the postsynaptic membrane binds neurotransmitter?
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In addition to diffusion, what are two other mechanisms that terminate neurotransmitter activity?
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Choose the correct order of these events during synaptic activity.
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How is an action potential propagated along an axon?
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Why does the action potential only move away from the cell body?
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The velocity of the action potential is fastest in which of the following axons?
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Where in the neuron is an action potential initially generated?
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The depolarization phase of an action potential results from the opening of which channels?
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The repolarization phase of an action potential results from __________.
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What is the magnitude (amplitude) of an action potential?
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In a synapse, neurotransmitters are stored in vesicles located in the __________.
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An action potential releases neurotransmitter from a neuron by opening which of the following channels?
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Binding of a neurotransmitter to its receptors opens __________ channels on the __________ membrane.
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Binding of the neurotransmitter to its receptor causes the membrane to __________.
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Which of the following neurotransmitters is broken down by an enzyme before being returned?
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The small space between the sending neuron and the receiving neuron is the
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A molecule that carries information across a synaptic cleft is a
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When calcium ions enter the synaptic terminal, they cause vesicles containing neurotransmitter molecules to fuse to the plasma membrane of the sending neuron.
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When neurotransmitter molecules bind to receptors in the plasma membrane of the receiving neuron, ion channels in the plasma membrane of the receiving neuron open.
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If a signal from a sending neuron makes the receiving neuron more negative inside, the receiving neuron is less likely to generate an action potential.
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What best describes the Na+ and K+ concentrations across a neuron's plasma membrane?
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Study Notes
Synaptic Activity
- Postsynaptic cells can be neurons, muscle cells, or secretory cells; presynaptic cells are always neurons.
- Chemically gated channels play a crucial role in the postsynaptic cell during synaptic activity.
- Calcium ions entering the synaptic terminal trigger vesicle fusion, allowing neurotransmitter release.
- Neurotransmitters bind to receptors on the postsynaptic membrane, facilitating ion diffusion across the membrane.
- Neurotransmitter release from presynaptic neurons occurs through exocytosis.
Mechanisms of Action
- Postsynaptic membranes contain chemically gated channels that specifically bind neurotransmitters.
- Neurotransmitter activity is terminated by reuptake and degradation, in addition to diffusion.
- The sequence of events in synaptic activity begins with the action potential arriving at the axon terminal.
Action Potential Propagation
- Action potentials propagate along axons via the influx of sodium ions, which leads to depolarization in adjacent areas.
- Action potentials move away from the cell body because previously depolarized areas are in a refractory state.
- Small myelinated axons transmit action potentials at the highest speeds.
- The initial generation of an action potential occurs at the axon hillock.
Ion Channel Dynamics
- The depolarization phase involves the opening of voltage-gated Na+ channels.
- Repolarization occurs through the opening of voltage-gated K+ channels, crucial for returning the membrane potential to resting state.
- An action potential has a magnitude (amplitude) of approximately 100 mV.
Neurotransmitter Storage and Action
- Neurotransmitters are stored in vesicles located within the presynaptic neuron.
- Action potentials facilitate neurotransmitter release by opening voltage-gated Ca2+ channels.
- Binding of neurotransmitters to receptors on the postsynaptic membrane opens chemically gated channels, resulting in membrane depolarization or hyperpolarization.
- Acetylcholine is a neurotransmitter that is enzymatically broken down before it is recycled back to the presynaptic neuron.
Synapse Structure
- The synaptic cleft is the small gap between the presynaptic and postsynaptic neurons.
- Neurotransmitters are molecular messengers that carry information across the synaptic cleft.
- Calcium influx in the synaptic terminal prompts the fusion of vesicles containing neurotransmitters with the presynaptic neuron's plasma membrane.
- The binding of neurotransmitters to receptors in the receiving neuron opens ion channels, influencing the likelihood of action potential generation.
Ion Concentrations
- Sodium (Na+) concentration is higher outside than inside the neuron, while potassium (K+) concentration is higher inside than outside, creating an electrochemical gradient vital for action potential generation.
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Description
Test your understanding of the nervous system with these flashcards covering key concepts from Chapter 11. Learn about presynaptic and postsynaptic cells, synaptic activity, and the role of calcium. Perfect for students looking to reinforce their knowledge in neuroscience.
