Introduction to Psychobiology Part 1 (Neurons)

Structure and Functions of Cells of the Nervous System

For more information about biopsychology, please check out "Physiology of Behavior" by Neil Carson.

We'll start the series by talking about the structures of the nervous system. Let's start with neurons. They are cells in the central nervous system (CNS) that process information (1). There are several types such as sensory neurons, which receive info from places such as the skin and sends it to the CNS (2), motor neuron, which sends info to places such as muscles so they can move, and interneurons, which are located between a sensory and a motor neuron (4).

Fun Fact: It is estimated that there are around 100 billion neurons in the brain (4)

We already talked about the CNS, but what is it? Well, to put it simply, it is composed of the brain and the spinal cord. If you noticed that there is a CENTRAL nervous system, then there should be one not so central. This is called peripheral nervous system (peripheral means outside), and it's every part of the nervous system that is outside of the brain and spinal cord.

Let us go back to neurons and talk about their parts. The structure of a neuron depends on its type, however there are similitudes between all of them. These include the soma, which is the cell body of a neuron, the dendrites, which look like tree branches and receive information, an axon, which is the part of the neuron that sends info, the synapse, which is the space between a terminal button and a dendrite.

Types of neurons

The most common type of neuron is called multipolar (3). This has one axon and many dendrites attached to its soma. A bipolar neuron has an axon from one side and a dendrite from the other.

Bipolar Neuron

Another type is the unipolar neuron. This cell has only one stalk that divides into the axon and the dendrites. Bipolar cells are usually found in sensory systems such as vision. Unipolar neurons usually work with somatosensory functions such as feeling pain and temperature (5). Both of them receive information from the physical world and send it into the CNS.

One way of sending information is with neurotransmitters. They are released by the terminal buttons when an action potential happens. A neurotransmitter is a chemical that has an effect on another neuron (remember how the synapse is the space between a terminal button and a dendrite? Well, when the neurotransmitter is released it travels in this space in search of a receptor usually on a dendrite of another cell) either by inhibiting or exciting it. This is how neurons communicate.


Physiology of Behavior by Neil Carson