Question

Order the sequence of events following an action potential in a presynaptic neuron that leads to an action potential in a postsynaptic neuron.

Ligand-gated ion channels of postsynaptic neuron open. Neurotransmitter molecules bind to receptor sites of post-synaptic neuron. Neurotransmitter molecules diffuse into the synaptic cleft. Vesicles release neurotransmitter molecules. Action potential depolarizes presynaptic neuron.

Action potential depolarizes presynaptic neuron. Vesicles release neurotransmitter molecules. Neurotransmitter molecules diffuse into the synaptic cleft. Neurotransmitter molecules bind to receptor sites of post-synaptic neuron. Ligand-gated ion channels of postsynaptic neuron open.

Action potential depolarizes presynaptic neuron. Vesicles release neurotransmitter molecules. Neurotransmitter molecules diffuse into the synaptic cleft. Ligand-gated ion channels of postsynaptic neuron open. Neurotransmitter molecules bind to receptor sites of post-synaptic neuron.

Answer 1

The sequence includes the action potential depolarizing the presynaptic neuron, release of neurotransmitters, diffusion in the synaptic cleft, binding to receptors, and opening of ligand-gated ion channels in the postsynaptic neuron.

Step-by-step explanation:

The sequence of events following an action potential in a presynaptic neuron that leads to an action potential in a postsynaptic neuron is as follows:

1. Action potential depolarizes presynaptic neuron, causing the opening of voltage-gated Na+ channels.
2. Vesicles release neurotransmitter molecules into the synaptic cleft due to the influx of Ca2+ ions which occurs when voltage-gated Ca2+ channels open.
3. The neurotransmitter molecules diffuse into the synaptic cleft.
4. These molecules bind to receptor sites on the post-synaptic neuron, specifically to ligand-gated ion channels.
5. As a result, the ligand-gated ion channels of the postsynaptic neuron open, allowing ions to flow in and potentially generating a postsynaptic action potential.

For example, the neurotransmitter acetylcholine can cause an excitatory postsynaptic potential (EPSP) by opening postsynaptic Na+ channels when it binds to its receptors. Conversely, neurotransmitter GABA, when binding to its receptors, can open Cl- channels leading to inhibitory postsynaptic potentials (IPSPs) and hyperpolarization of the postsynaptic membrane.