The parasympathetic nervous system decreases heart rate through a mechanism known as direct coupling. Here's a step-by-step explanation:

1. The parasympathetic nervous system is activated, which is often in response to a calm or relaxed state.
2. This activation triggers the release of the neurotransmitter acetylcholine.
3. Acetylcholine binds to muscarinic receptors (specifically M2 receptors) on the pacemaker cells of the heart.
4. This binding causes a G protein inside the cell to activate, which is the "direct coupling" part of the process.
5. The activated G protein then opens potassium channels in the cell membrane.
6. The opening of these channels allows potassium ions to leave the cell, which hyperpolarizes the cell and makes it less likely to fire.
7. This decrease in cell firing leads to a slower heart rate.

So, the answer is a) Direct coupling.

Question

The parasympathetic nervous system decreases heart rate through a mechanism known as direct coupling. Here's a step-by-step explanation:

1. The parasympathetic nervous system is activated, which is often in response to a calm or relaxed state.
2. This activation triggers the release of the neurotransmitter acetylcholine.
3. Acetylcholine binds to muscarinic receptors (specifically M2 receptors) on the pacemaker cells of the heart.
4. This binding causes a G protein inside the cell to activate, which is the "direct coupling" part of the process.
5. The activated G protein then opens potassium channels in the cell membrane.
6. The opening of these channels allows potassium ions to leave the cell, which hyperpolarizes the cell and makes it less likely to fire.
7. This decrease in cell firing leads to a slower heart rate.

So, the answer is a) Direct coupling.

Knowee AI · Accepted Answer

The parasympathetic nervous system decreases heart rate through a mechanism known as direct coupling. Here's a step-by-step explanation:

1. The parasympathetic nervous system is activated, which is often in response to a calm or relaxed state.
2. This activation triggers the release of the neurotransmitter acetylcholine.
3. Acetylcholine binds to muscarinic receptors (specifically M2 receptors) on the pacemaker cells of the heart.
4. This binding causes a G protein inside the cell to activate, which is the "direct coupling" part of the process.
5. The activated G protein then opens potassium channels in the cell membrane.
6. The opening of these channels allows potassium ions to leave the cell, which hyperpolarizes the cell and makes it less likely to fire.
7. This decrease in cell firing leads to a slower heart rate.

So, the answer is a) Direct coupling.

What mechanism does the parasympathetic nervous system use to decrease heart rate?Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer.aDirect couplingbIP3/DAG second messengercEnzyme linkeddcAMP second messenger

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