The Biology of Behavior: Is the Brain the Organ of Mental Life? 31
Objectives
After completing the chapter, you will be able to
- explain the way in which a neuron functions;
- describe the structure of the nervous system;
- specify some of the principal structures and functions of the brain;
- differentiate between the functions of the left and right hemispheres of the brain;
- identify the endocrine glands and their functions.
In the 1983 Steve Martin film The Man with Two Brains,a woman’s personal-
ity is changed when her own brain is removed and then replaced with a different
one. The plot is based on the assumption that the brain is the organ of mental life.
This assumption, associated with the biological viewpoint (see chapter 1), sees the
activityof the brain and nervous system as the basis of consciousness. The rela-
tionship between the brain and the mind in this way of looking at things is
roughly the same as the relationship of a piano to the melody that one hears when
the piano is played. The piano, like the brain, is a physical organ. The melody, like
the mind, is somewhat less tangible.
This chapter explores behavior from the biological point of view. Of particu-
lar interest are (1) the brain and nervous system and (2) the endocrine system.
The biological viewpoint sees the of the brain and nervous system as the basis
of consciousness.
Answer: activity.
The Neuron: The Building Block of the Nervous System
The principal functional units of the brain and the nervous system are neurons.
The neuronis a living cell with a cell wall and a nucleus. Unlike other cells of the
body, neurons specialize in transmitting messages. Of particular importance are
two structures called the dendriteand the axon.A neuron often has more than
one dendrite; dendrites are reminiscent of a root system. They act like antennas,
picking up information and sending it in the direction of the cell body. The axon
extends from the cell body like a long filament. Although there can be more than
one dendrite, there is always just one axon. The axon consistently sends informa-
tion away from the cell body, often to an adjacent neuron.
