junction between 2 neurons that communicates the message from the presynaptic neuron to the post-synaptic neuron.
postganglionic fibers are long, highly branched axons influence many organs, release norepinephrine NE (adrenergic).
postganglionic fibers are short, very few branched axons for localized effect, release acetylcholine (cholinergic).
cholinergic fibers release the neurotransmitter AcH:
in all ANS preganglionic axons, all parasympathetic postganglionic axons.
adrenergic fibers release the neurotransmitter NE
in most sympathetic postganglionic axons,
exceptions: sympathetic postganglionic fibers secrete AcH at sweet glands and some blood vessels in skeletal muscles.
Parasympathetic and Sympathetic nervous system
-a subdivision of the PNS,
-not under conscious control,
-controlled by medulla oblongata and hypothalamus,
-PNS supplies stimulation via motor nerves to smooth and cardiac muscle and to glands.
-conscious control of ANS,
-example: Yoga, Meditation,
-monitoring devices useful for: epilepsy, digestive problems, chronic headaches, high blood pressure, generalized stress, anxiety, insomnia.
Four E's of sympathetic division
norepinephrine, "fight or flight";
Exercise, Excitement, Emergency, Embarrassment.
effects of fight or flight:
increased cardiac activity and blood pressure, dilation of skeletal muscle blood vessels, constriction of blood vessels in skin, dilation of pupil, inhibition of gut and urinary bladder contractions, increase blood glucose and free fatty acid levels, dilation of bronchial smooth muscle, secretion of viscous saliva, sweating, lower threshold for reticular formation activation, liver produces glucose to provide energy for muscle contractions
Three D's of parasympathetic division
acetylcholine, "rest and digest";
Digestion, Defecation, Diuresis (urination)
effects of parasympathetic:
decreased cardiac activity, secretion of watery saliva and stimulation of GI secretions, contraction of urinary bladder, increased insulin and glucagon secretion, bronchiole constriction.
Five autonomic plexuses
celiac ganglion and plexus,
mesenteric ganglion and plexus,
components of an autonomic reflex arc:
(2) Sensory Neuron,
(3) Integration Center, (medulla/hypothalamus)
(4) Motor Neuron,
(5) Effector (smooth or cardiac muscle, or gland).