Question

130 exam 3 - chapters 10 and 11 nervous syst
how is an impulse transmitted from one neuron to another?
multiple choice
○ an impulse stimulating presynaptic dendrites causes the release of neurotransmitters into a synaptic cleft.
○ a neurotransmitter traveling from postsynaptic axons crosses the synapse to presynaptic dendrites or a cell body
○ a neurotransmitter traveling from presynaptic dendrites crosses the synapse to postsynaptic axons or a cell body
○ an impulse stimulating a presynaptic axon causes the release of neurotransmitters into a synaptic cleft.

Explanation:

1. Analyze each option:

• Option 1: Impulse stimulates presynaptic dendrites to release neurotransmitters. Incorrect, as impulses reach presynaptic axon terminals, not dendrites, to trigger neurotransmitter release.
• Option 2: Neurotransmitter travels from postsynaptic to presynaptic. Incorrect, direction is presynaptic to postsynaptic.
• Option 3: Neurotransmitter travels from presynaptic (despite "dendrites" likely being a typo for axon terminal) to postsynaptic across the synapse, matching the general direction of neurotransmitter movement between neurons.
• Option 4: Impulse stimulates presynaptic axon to release neurotransmitters. Incorrect, as it's the axon terminal (end of axon), not the entire axon, where neurotransmitters are released.

Answer:

The correct option is: "A neurotransmitter traveling from presynaptic dendrites crosses the synapse to postsynaptic axons or a cell body" (the third option, though the original text's option numbering might have a typo, but based on the description of neurotransmitter movement across synapse from presynaptic to postsynaptic structures, this option describes the process where a neurotransmitter (released from presynaptic neuron, here said to travel from presynaptic dendrites - likely a typo for axon terminal, but the key is crossing synapse to postsynaptic) moves across the synapse to the postsynaptic neuron's axons or cell body. Wait, actually, the correct physiological process is: An impulse reaches the presynaptic neuron's axon terminal, causing neurotransmitters to be released into the synaptic cleft. These neurotransmitters then cross the cleft and bind to receptors on the postsynaptic neuron's dendrites, cell body, or axon. But among the given options, the option "A neurotransmitter traveling from presynaptic dendrites crosses the synapse to postsynaptic axons or a cell body" (assuming the "presynaptic dendrites" is a typo for axon terminal) is the one that describes the neurotransmitter crossing the synapse to the postsynaptic structure. Wait, no, let's re - evaluate:

Wait, the options:

1. An impulse stimulating presynaptic dendrites causes the release of neurotransmitters into a synaptic cleft. (Incorrect, impulse reaches presynaptic axon terminal, not dendrites, to release neurotransmitters)

1. A neurotransmitter traveling from postsynaptic axons crosses the synapse to presynaptic dendrites or a cell body. (Incorrect, direction is presynaptic to postsynaptic)

1. A neurotransmitter traveling from presynaptic dendrites crosses the synapse to postsynaptic axons or a cell body. (Even with the dendrites typo, the direction is presynaptic to postsynaptic, and neurotransmitter crossing synapse to postsynaptic structure)

1. An impulse stimulating a presynaptic axon causes the release of neurotransmitters into a synaptic cleft. (This is close, but the option as per the image's fourth option: "An impulse stimulating a presynaptic axon causes the release of neurotransmitters into a synaptic cleft." Wait, maybe I misread the options. Let's re - list the options as per the image:

First option: "An impulse stimulating presynaptic dendrites causes the release of neurotransmitters into a synaptic cleft."

Second option: "A neurotransmitter traveling from postsynaptic axons crosses the synapse to presynaptic dendrites or a cell body."

Third option: "A neurotransmitter traveling from presynaptic dendrites crosses the synapse to postsynaptic axons or a cell body."

Fourth option: "An impulse stimulating a presynaptic axon causes the release of neurotransmitters into a synaptic cleft."

Wait, the correct process is: When an action potential (impulse) reaches the presynaptic neuron's axon terminal, it triggers the release of neurotransmitters into the synaptic cleft. Then the neurotransmitters diffuse across the cleft and bind to receptors on the postsynaptic neuron (dendrites, cell body, or axon).

So among the options, the fourth option: "An impulse stimulating a presynaptic axon causes the release of neurotransmitters into a synaptic cleft." is incorrect because it's the axon terminal, not the entire axon, but the third option: "A neurotransmitter traveling from presynaptic dendrites crosses the synapse to postsynaptic axons or a cell body." has a typo (presynaptic dendrites should be axon terminal), but it describes the neurotransmitter moving from presynaptic (source) to postsynaptic (target) across the synapse. Alternatively, maybe the intended correct option is the third one. But actually, the correct physiological process is that neurotransmitters are released from presynaptic axon terminals, cross the synapse, and bind to postsynaptic structures (dendrites, cell body, axon). So the option that says a neurotransmitter travels from presynaptic (even with the dendrites typo) to postsynaptic across the synapse is the third option: "A neurotransmitter traveling from presynaptic dendrites crosses the synapse to postsynaptic axons or a cell body".