Contraction of smooth muscles.
Constriction and dilation of the pupils.
Constriction and dilation of the blood vessels.
Rate and force of cardiac muscle contraction.
b. It has always been thought that autonomic control is an "automatic" function
and not of conscious control. However, recent research indicates that conscious control
is possible with proper training. A classic example is the control of headache and
hypertension by utilizing biofeedback techniques.
c. In the autonomic nervous system, there are two neurons, one following the
other, that connect the CNS with the viscera of the body.
(1) The first neuron extends from the CNS to a ganglion, and is therefore
called the preganglionic neuron. The cell body of the second neuron is located within
(2) The processes of the second neuron extend from the ganglion to the
viscera. The second neuron is called the postganglionic neuron.
d. The ANS is organized into two major divisions:
(1) The sympathetic nervous system, also called the thoraco-lumbar outflow
because the associated neurons originate in the thoracic and lumbar regions of the
(2) The parasympathetic nervous system, also called the cranio-sacral
outflow because the associated neurons originate in the brainstem and the sacral region
of the spinal cord.
e. Under ordinary circumstances, the sympathetic and parasympathetic nervous
systems have opposite effects on bodily activities. That is, one system will stimulate
action and the other will inhibit action. The interplay maintains bodily function in a state
f. The "fight or flight" response is produced by the sympathetic nervous system
when conditions of stress or threat prevail.
(1) The sympathetic nervous system activates energy producing structures
and helps the body expend effort and energy wisely.
Heart rate increases.