Question

The junction between the axon of one neuron and the dendrite of the next is called as
a. Junction point
b. A synapse
c. A joint
d. Constant bridge

Answer 1

Hint: A neuron is a nerve cell with all its branches and forms the structural and functional unit of the nervous system. It is the communication unit of most nervous systems. It can detect, receive and conduct the nerve impulses to various parts of the body.

Complete answer:
A neuron is formed of two parts- cyton and nerve processes.
> Cyton is also called soma or perikaryon. It is of variable shape and its granular cytoplasm is called neuroplasm.

> Nerve processes are one or more cytoplasmic processes arising from the cyton. These are of two types-axon and Dendron.
- Dendrons are one or more small sized tapering processes that are highly branched to form the terminal arborization. These are afferent in nature and conduct the nerve impulses towards the cyton so also called receptive input region.
- Axons are single. Long and cylindrical processes whose primary function is to conduct the nerve impulses away from the cyton, so it is efferent in nature.

The neurons lie end to end forming a chain or may be aggregated into cell mass. Each neuron receives a nerve impulse through its dendron and passes it to the next neuron through its axon. An axon ends into a number of branches, the ends of which form knob-like swellings called synaptic knobs which come to lie very close to the dendron of the next neuron. Such a junction between the synaptic knob of the axon of one neuron and the dendron of the next neuron is called synapse.

Hence, the correct answer is option (B).

Note: Nerve impulses are transmitted from axon to dendron with the help of chemicals called neurotransmitters that are produced by secretory vesicles of the synaptic knobs. These neurotransmitters cause stimulation or inhibition of next neurons or effector cells.