ANS Flashcards
Somatic NS
Originates in the CNS or brainstem and sends one axon directly to the muscle
ANS
Modulates the visceral organs; primarily involved in maintaining homeostasis of the internal environment
Location of parasym ganglia
Normally located close to the target organ
Description of parasym nerve fibers
Long preganglionic; short postganglionic fibers
Ach
Neurotransmitter at PNS ganglia, adrenal medulla and somatic muscular junction; acting on nicotinic receptors
Parasym function
Conserve energy, enhance digestion
Symp NS origin
Thoracic and upper lumbar spinal cord
Description symp nerve fibers
Short preganglionic; long postganglionic fibers
What are the symp NTs and where do they act and which receptors
Acetylcholine at the ganglia, acting on nicotinic receptors
-norepinephrine at effector junctions (alpha and beta adrenergic receptors)
Symp NS function
Mobilize body for “fight or flight”, with continuous modulation of organ function
Sweat glands
Effector organ where acetylcholine is the neurotransmitter in the symp NS
Heart receptor/NT
Beta 1
-norepinephrine, epinephrine
Lung/bronchi receptor/NT
Beta 2/epinephrine
Action of B1 receptor agonist at the heart
Increase cAMP, increase HR, increase force of contraction
Action of B2 receptor agonist at the lung
Increase cAMP, relaxation
Cholinergic nerve synthesizes ______ by
Synthesize acetylcholine from choline and acetate by choline acetyltransferase
Noradrenergic fibers or nerves synthesizes _____ by
Synthesize NE from tyrosine to DOPA using tyrosine hydroxylase; DOPA is converted to dopamine
Dopamine in nerve terminals
Converted to NE by dopamine-beta-hydroxylase
Epi converted from _____ in adrenal medulla
Converted from NE by phenyl-ethanolamine-N-methyltransferase
Termination of NE
Primarily reuptake; additionally monoamine oxidase and catechol-O-methyltransferaseLung SNS
Lung in the symp
bronchodilation
Lung in parasym
bronchoconstriction
Heart in symp
Through beta 1 receptors, stimulates HR, increases AV nodal conduction, and increases force of contraction
Heart in parasymp
Through muscarinic M2 receptors, has negative effect on HR and AV nodal condution
Vascular alpha-1 receptors of symp
Predominate in skin and viscera; stimulation causes vasoconstriction in these vascular beds
Vascular beta-2 receptors of symp
Predominate in skeletal muscle; stimulation causes vasodilation
Epi
Stimulates both alpha-1 and beta-2 receptors; redirects blodflow to muscles
Baroreceptors
Reflex phenomena, sensed by changes in blood pressure; coordinated response in PNS and SNS
Pupil
Controlled by two muscles of the iris. The light reflex causes constriction of the circular muscle through the PNS (M3 receptors)
Ciliary muscle
Symp NS control (beta-2 receptors) for relaxation allowing far vision; M3 receptors (parasymp NS) causing contraction for near vision (accommodation)
Liver
Sympathetic nervous system stimulation leads to an increase in glucose through beta-2 receptors
Action of alpha-1 in blood vessels
Symp NS effect to decrease radius in the visera
