Question

Synapse is………………….?

Answer 1

This structure in the nervous structure permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or to the target effector cell. The small gap in this structure separates two neurons.

Complete answer:
Synapse or neuronal junction, is the main site where transmission of electric nerve impulses between two nerve cells (neurons) or between a neuron and a gland or muscle cell (effector)takes place. The synaptic connection formed between a neuron and a muscle cell is called a neuromuscular junction.
Electric synapses permit direct communications between neurons whose membranes are fused by allowing ions to flow between the cells through channels called gap junctions. It is found in invertebrates and lower vertebrates. In addition to this gap junctions allow faster synaptic transmission as well as the synchronization of entire groups of neurons. Gap junctions can also be found in the human body and are most often between cells in most organs and between glial cells of the nervous system. Large and complex vertebrates have evolved chemical transmission systems where the transmission of multiple messages over longer distances are required.

Additional information:
Each terminal, at a chemical synapse of a nerve fibre is called a presynaptic fibre that swells to form a knoblike structure and is separated from the fibre of an adjacent neuron, called a postsynaptic fibre, by a microscopic space known as a synaptic cleft. A typical synaptic cleft can be about 0.02 micron wide. When a nerve impulse arrives at a presynaptic terminal, it starts to move towards the presynaptic membrane of the synaptic vesicles, which then fuse with the membrane and release a chemical substance called a neurotransmitter. This specific substance transmits the nerve impulse to the postsynaptic fibre by diffusing across the synaptic cleft and binding to the receptor molecules on the postsynaptic membrane. This action of chemical binding, in turn alters the shape of the receptors, and initiates a series of reactions that open channel-shaped protein molecules. Electrically charged ions then flow freely through the channels into or out of the neuron.

So, the correct answer is ‘The gap between two neurons’.

Notes:
A single neurotransmitter may bring different responses from different receptors. For example: norepinephrine is a common neurotransmitter in the autonomic nervous system that binds to some receptors that excite nervous transmission and to others that inhibit it.