3. Cholinergic fibers are nerve endings that
release acetylcholine.
Adrenergic fibers are nerve fibers that
release norepinephrine.
4. Cholinergic receptors
Nicotinic receptors are acetylcholine-
binding receptors that bind to nicotine.
Muscarinic receptors are acetylcholine-
binding receptors that bind to muscarine.
5. Adrenergic receptors
Alpha is a type of adrenergic receptor that
usually causes a stimulatory effect when it
binds with norepinephrine or epinephrine.
Beta adrenergic receptors usually cause an
inhibitory effect when bound to NE or
epinephrine.
7. Sympathetic and
parasympathetic tone
Sympathetic tone is a state of partial
vasoconstriction of the blood vessels
maintained by sympathetic fibers.
Vasomotor fibers are sympathetic nerve
fibers that regulate the contraction of
smooth muscle in the walls of blood
vessels.
8. Parasympathetic tone is a state of
parasympathetic effects that prevents
unnecessary heart accelerations and
promotes normal digestive activity.
9. Effects of the parasympathetic
and sympathetic divisions on
various organs
10. Target organ/system Parasympatheic effects Sympathetic effects
Eye (iris) Constricts pupils Dilates pupils
Eye (ciliary mucle) Stimulates muscles for close No effect
accomodation of lens
Glands Stimulates secretory activity Inhibits secretory activity
Sweat glands No effect Stimulates copious sweating
Adrenal medulla No effect Stimulates secretion of epinephrine
and norepinephrine
Arrector pili muscles No effect Stimulates contraction
Heart muscle Decreases rate Increase rate and force
Coronary blood vessels Constricts Causes vasodilation
Bladder/urethra Relax urethral sphincter; Constricts urethral sphincter;
promotes voiding inhibits voiding
Lungs Constricts bronchioles Dilates bronchioles
11. Target organ/system Parasympatheic effects Sympathetic effects
Digestive tract organs Increases peristalsis Decreases glandular acivity and
constricts sphincters
Liver No effect Releases glucose into blood
Gall bladder Stimulates bile secretion Inhibits bile secretion
Kidney No effect Decreases urine output; vasoconstriction
Penis Causes erection Causes ejaculation
Vagina/clitoris Causes erection Reverse peristalsis
Blood vessels No effect Constricts blood vessels, increases
blood pressure
Blood coagulation No effect Increases coagulation
Cellular metabolism No effect Increases metabolic rate
Adipose tissue No effect Stiulate lipolysis
Mental activity No effect Increases altertness
13. Cortical controls
Biofeedback training provides an awareness
of visceral activities, enabling an element of
voluntary control over autonomic body
functions.
