The Biology of Behavior: Is the Brain the Organ of Mental Life? 35
autonomic activity. Excitement provides an example. When you are excited, your
blood pressure goes up, your pulse increases, and the rate of respiration rises.
These are all due to the activity of the sympathetic division. The sympathetic divi-
sion is sometimes compared to the gas pedal on a car; it makes the whole system
go forward with increased speed. (There are exceptions to the generalization
made in this paragraph.)
(a) The two divisions of the autonomic nervous system are the and the
.
(b) What division of the autonomic nervous system is active primarily when there is an
increase in autonomic activity?
Answers: (a) sympathetic division; parasympathetic division; (b) The sympathetic
division.
The parasympathetic division is active primarily when there is a decreasein
autonomic activity. Relaxation provides an example. When you are relaxed, your
blood pressure goes down, your pulse decreases, and your respiration rate falls.
The parasympathetic division is sometimes compared to the brakes on a car; they
can be used to make the whole system slow down. (Again, there are exceptions to
the generalization made in this paragraph.)
As you will see in chapter 6, the chapter on learning, classical conditioning
refers primarily to the activity of the autonomic nervous system.
Let’s return to the somatic division of the peripheral nervous system. The
Greek word somameans “body.” Consequently, the somatic division controls the
actions of the body. When you walk, talk, move your arms, or use your fingers,
the somatic division regulates these actions. As you will see in chapter 6, operant
conditioning refers primarily to the activity of the somatic nervous system.
(a) What division of the autonomic nervous system is active primarily when there is a
decrease in autonomic activity?
(b) The Greek word somameans.
Answers: (a) The parasympathetic division; (b) “body.”
The Brain: The CEO of the Organization
The brain is actually a part of the nervous system. As indicated earlier, the brain
and the spinal cord constitute one of the two major divisions of the nervous sys-
tem—the central nervous system. Our main concern in this section is with the
brain, not the spinal cord. However, let us note that the spinal cord,protected
by the bones of the spine, is a two-way communication highway. Sensory mes-
