Select the correct statement regarding chemical synapses. A) Cells with gap junctions use chemical synapses. B) The release of neurotransmitter molecules gives cells the property of being electrically coupled. C) Neurotransmitter receptors are located on the axons terminals of cells. D) The synaptic cleft uses the action potential to transmit a chemical signal to the post synaptic cell.

The correct statement regarding chemical synapses is option D) The synaptic cleft uses the action potential to transmit a chemical signal to the post synaptic cell.

Explanation:

When a motor neuron approaches the muscle, it branches out into several extensions that end in areas called synaptic boutons, which can release neurotransmitters. These synaptic boutons are situated over a specialized region of the muscle called the end-plate. These synaptic boutons are separated from the endplate by a space called the synaptic cleft.

The synaptic space or synaptic cleft is the small space that exists between the synaptic boutons of one neuron and the postsynaptic cell. It is an extracellular space between 20 to 40 nanometers and filled with synaptic fluid that is part of the neuronal synapse, along with pre and postsynaptic neurons. Thus, it is in this cleft where the transmission of information from one presynaptic neuron to the post-synaptic neuron occurs.

When an action potential travels down the motor neuron, it causes the release of acetylcholine into the synaptic cleft. Acetylcholine binds to its receptors in the muscle membrane, which causes ion channels to open and allow positive sodium ions to flow into the postsynaptic cell. This produces depolarization of the postsynaptic cell, called an "excitatory postsynaptic potential".

This depolarization leads to the opening of voltage-gated sodium channels, which causes the end-plate potential to lead to an action potential. This action potential travels along with the muscle fiber and causes contraction of the muscle.