Video Transcript
What are the two divisions of the autonomic nervous system? (A) Sensory and motor, (B) sympathetic and parasympathetic, (C) the brain and the
spinal cord, (D) peripheral and central.
To answer this question, we need to recall the organization of the peripheral nervous
system, which will help us to specifically recall the structure and function of the
autonomic nervous system. The peripheral nervous system is subdivided three times, with each of the
subdivisions contributing to the control of specific functions within our body. First, the peripheral nervous system is divided into the motor and sensory
divisions. Then, the motor division is further subdivided by the type of motor function which is
to be carried out. These subdivisions are called the autonomic and somatic nervous systems.
The autonomic nervous system controls involuntary motor functions, while the somatic
nervous system controls all of our voluntary motor functions. The involuntary functions of the autonomic nervous system are responsible for all the
subconscious activities that keep our bodies functioning even when we are
asleep. A few examples of the functions controlled by the autonomic nervous system are
digestion, respiration, urination, and heart rate.
Since these involuntary functions need to be activated or inhibited at very different
times depending on the environmental context, the autonomic nervous system is
further subdivided into the sympathetic and parasympathetic nervous systems. These two systems work together to keep the body’s functions balanced to maintain a
constant internal environment, which is called homeostasis. The homeostatic balance of the body is maintained by the parasympathetic and
sympathetic nervous systems performing opposing actions to one another. For example, one system controls an increase in heart rate, while the other system
controls a decrease in heart rate.
The sympathetic nervous system is responsible for preparing the body for action and
controls increases in the bodily function. These responses are usually seen when we are preparing to make a fight-or-flight
response. Examples of the fight-or-flight functions include dilation of the pupils,
acceleration of the heart rate, and stimulation of glucose production as well as
release to increase the available energy within the body.
The parasympathetic nervous system is responsible for decreases in bodily
function. These responses are usually seen when we’re preparing to rest or feed, which is why
these responses are known as the rest-and-digest response. Examples of the rest-and-digest functions include constriction of the pupils, slowing
of the heart rate, and stimulation of bile release to aid in digestion.
Now that we have reviewed the subdivisions of the autonomic nervous system, which
include the sympathetic and parasympathetic nervous systems, we can answer the
question. The two divisions of the autonomic nervous system are the sympathetic and
parasympathetic.
