Neurons are regarded as the fundamental elements of human behavior. Neurons or nerve cells are the basic elements of the nervous system (Feldman, 55). The basic structure of neuron consists of a cell body with a nucleus in the center that controls the entire nerve cell; About one trillion neurons are held together by glial cells present within each cell; these are also responsible for nourishing the neurons. At one end, a neuron has fiber like structures called the dendrites and at the other end it has a long tube like structure called axon with a small bulb like ending called terminal buttons. The former function as receptors of messages and the latter is responsible for transmitting the messages to dendrites of the next neuron. The entire neuron is insulated with specialized fat and protein cells called the myelin sheath. Neurons are capable of communicating with other cells and transmitting information across very long distances. The length of dendrites and axons also vary from few millimeters to 3 feet (Feldman, 2008).
With this simple structure, neurons play complex roles in the human body and help in functioning of the brain; in turn they control the functioning of human body to internal as well as external stimuli. The basic process involves transmission of electrical messages from one neuron to the next until the message reaches the target organ. This transmission happens in the form of synapse, which is the signal transmitted through neurotransmitters, chemical substances discharged by the terminal buttons of axons. Sometimes signals may be transmitted even without the neurotransmitters required to bridge the gap. These neurotransmitters interact with the dendrites, thereby activating or constraining the subsequent neurons; this process is referred to as firing or graded potential (Wittig, 2000). Although more than 50 types of neurotransmitters have been found, some of the important ones include endorphins responsible for pain