The autonomic nervous system was discussed in lesson 6 of this subcourse. In
that lesson, you learned of the sympathetic division of this nervous system. Specifically,
it was stated that the sympathetic nervous system is frequently referred to as the
adrenergic nervous system because of its transmitter epinephrine that is more
commonly known by its trade name, "Adrenalin." The adrenergic nervous system
prepares the body for stress situations. Stimulation of the adrenergic nervous system
has the general effect of expending energy. When a person is scared, this system
prepares the body for the fight or flight response.
MECHANISMS OF ACTION OF AGENTS WHICH STIMULATE SYMPATHETIC
Drugs that stimulate the sympathetic nervous system have a variety of
mechanisms of action. These include:
a. Mimicking the action of the transmitter norepinephrine. See figure 7-1 for a
diagrammatic representation of the sympathetic nervous system.
Rapidly displacing the transmitter from its storage site to activate the receptor.
Blocking the uptake of the transmitter into storage sites.
Inhibiting enzymes that break down the transmitter.
Figure 7-1. Diagrammatic representation of the sympathetic nervous system.