Psychology: Measurement and Statistics
Psychology: Biological Bases of Behavior
Behavior and mental processes result from activities in the body's nervous system and other physiological systems.
Structure. The basic unit of the nervous system is a cell known as the neuron (Figure 1 ). It is estimated that the nervous system contains over 11 billion neurons. The neuron, which is covered by a cell membrane, consists of
-
dendrites, branched appendages that carry information to the cell body
-
a cell body (soma), which contains the nucleus
-
an axon, which conveys information away from the cell body
|
|
|||
|
|||
|
|
|||
|
|||
|
|
Some axons are covered with a
myelin sheath (interspersed with spaces called
nodes of Ranvier), which aids in neural transmission. Neurons are surrounded by
glial cells, which nourish the neurons and hold them in place; these cells are the basis of the myelin sheaths.
Axon terminals are branched and contain
terminal buttons, tiny swellings that in turn contain
synaptic vesicles (Figure
2 ). Synaptic vesicles are filled with chemicals called
neurotransmitters, which assist in transmission of information to other neurons.
|
|
|||
|
|||
|
|
|||
|
|||
|
|
Types of neurons. There are three types of neurons:
-
Sensory neurons are located in the body's sense organs (for example, the eye, ear, or nose) and send information from these organs to the brain.
-
Motor neurons convey information from the nervous system to the body's organs, glands, and muscles.
-
Interneurons (association neurons) transmit information from one neuron to another within the nervous system.
