The
autonomic nervous system functions involuntarily to control
motor functions of the heart, lungs, other internal organs and
of the smooth muscles of the blood and lymph vessels.
(See diagram and text regarding the autonomic
nervous system innervation of the heart and its effects
on the sinus and av nodes).
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to enlarge
It is
divided into two parts, as follows:
1) the parasympathetic coming from the mid and hind brain and
the spinal cord and able to cause constriction of the pupils
of the eyes and slowing of the heart rate amongst other functions;
2)
sympathetic orginating in the spinal cord and concerned with
causing the involuntary response to alarm such as by speeding
the heart rate and raising the blood pressure.
