Ch 7 Part 1 -- PNS Autonomic -- VTPP 434

Ch 7 Part 1 -- PNS Autonomic -- VTPP 434

Sympathetic Nervous System

-nerve fibers originate in lateral horn of thoracic and lumber regions of spinal cord
-short preganglionic fibers
-long postganglionic fibers
-some preganglionic fibers synapse at collateral ganglion

Parasympathetic Nervous System

-nerve fibers originate from cranial & sacral regions
-long preganglionic fibers
-short preganglionic fibers

Terminal Ganglia

-area near or in effector organ where preganglionic parasympathetic fibers terminate
-area before Postganglionic parasympathetic fiber

Acetylcholine (ACh)

-neurotransmitter released by parasympathetic and sympathetic preganglionic fibers and
-released by parasympathetic post ganglionic fibers

Cholinergic fibers

-autonomic fibers that release ACh

Adrenergic Fibers

-autonomic fibers that release noradrenaline
-released by sympathetic postganglionic fibers

Cotransmitters

a neurotransmitter that is secreted along with a basic neurotransmitter

Varicosities

-endings of terminal branches of autonomic fibers that release neurotransmitter that diffuses over large area of effector organ
-diffused by gap junctions

Dual Innervation

-innervation of a single organ by both branches of autonomic nervous system
-helps precisly control organs

Sympathetic Dominance

-sympathetic fibers' rate o firing to an organ increases above tone level
-decrease in parasympathetic fibers to same organ
-balance can be targeted for specific organs

Adrenal Medulla

-a modified sympathetic ganglion
-lack post ganglionic fibers which are replaced by catecholamine hormones

Nicotinic Receptors

-a type of cholinergic receptor
-activated by nicotine
-found on all preganglionic autonomic receptor cell bodies
-ACh binding opens nonspecific cation channels (favors Na+ entry)
-electrochemical gradient causes entry

Muscarinic Receptors

-a type of cholinergic receptor
-activated by mushroom poison muscarine
-found on effector cell membranes
-fond on parasympathetic postganglionic receptor bodies
-bind with ACh from parasympathetic fibers
-use G-protein 2nd messenger systems

Alpha 1 Receptor

-prefers Norepinephrine > Epinephrine
-found mostly on sympathetic target tissues
-IP3-Ca2+ 2nd messenger
-causes excitatory response

Alpha 2 Receptor

-prefer Norepinephrine > Epinephrine
-mainly digestive organs target
-inhibits cAMP production
-causes inhibitory response
-Ex. less smooth muscle contraction in digestive tract

Beta 1 Receptor

-activate cAMP 2nd messenger pathway
-like Norepinephrine = Epinephrine
-located in the Heart
-causes an heart rate increase

Beta 2 Receptor

-activate cAMP 2nd messenger pathway
-like only Epinephrine
-located in smooth muscles of arterioles & bronchioles
-inhibits & relaxes the vessels to dilate them

Sympathetic Response

-heart rate increase
-increase heart force of contraction
-skin and organs blood vessels constricted
-muscles and heart blood vessels dilated
-Bronchiole dilation
-inhibits Lungs mucus secretion
-Relaxes gall bladder, urinary bladder, and digestive system
-Cessation of digestion
-promotes Lipolysis
-Increases sweat and salivary mucus
-decrease insulin
-increased glucagon, epinephrine, and norepinephrine
-increased alertness
-orgasmic contractions of reproductive

Parasympathetic Response

-decreased heart rate
-dilation of reproductive organs blood vessels
-bronchiolar constriction
-stimulate lungs mucus secretion
-increased motility of digestive system
-relaxes digestive system sphincters
-stimulates secretion of digestive system
-empties gall and urinary bladder by contracting
-release of insulin and glucagon and digestive enzymes from pancreas
-excites genitals