A living human being who is constantly influenced by environment cannot remain motionless. The various stimuli in his environment will be stimulating him every moment. In order to adjust with such environment he has to show some responses or reflexes.
There is no life without adjustment. Hence, there will be continuous reactions or responses/behaviours in some form or other.
In order to understand how he behaves and what stimulus elicits what response, we have to understand the biological basis of behaviour. The most important aspects in the body which are related to behaviour are nervous system, sense organs and endocrine glands. Before going into the details of nervous system, let us understand the basic aspects like neuron and synapse.
Neuron is the structural unit or the basic element of a nerve. Nerve is made up of many neurons. Neuron is comprised of three parts, Dendrites, Axon and End brushes. The dendrites will receive the impulses and pass on the same to another neuron through axon and end brushes.
The neuron will have a nucleus in its cell body which is the heart of the neuron. There are different types of neurons (Fig. 2.1).
The end brushes of one neuron and the dendrites of another neuron are not welded together. There exists a gap between these two substances called Synapse (Fig. 2.2). This is a junction or a cleft. A connection is formed between the end brushes of one neuron and dendrites of another neuron when the impulse is transformed. A chemical transmitter substance helps in this connection.
Acetylcholine, Dopamine, Serotonin, Epinephrine, Nor-epinephrine are some of the neuro transmitters. This is one way connection.