ANS Review

organs/tissues receive only sympathetic innervation 6

- blood vessels - hair follicles -sweat glands -liver -adrenal glands - kidneys

para S2-S4 -innervation 3

-colon -bladder -sex organs

para CNX -nuclei -path -innervation

-nuclei= dorsal motor nucleus of vagus -path dorsal motor nucleus of vagus--> visceral ganglia -innervation 1. heart 2. lung 3. stomach 4. liver 5. pancreases 6. small intestine 7. spleen 8. colon

para CNIII -nuclei -path -innervation 2

-nuclei= edinger westpahl nucleus -path edinger westpahl nucleus--> ciliary ganglion -innervation 1. pupillary constrictor 2. ciliary muscle

para CNIX -nuclei -path -innervation

-nuclei= inferior salivary nucleus -path= inferior salivary nucleus--> otic ganglion -innervation= 1. parotid gland

para CN VII -nuclei -path -innervation 3

-nuclei= superior salivatory -path superior salivatory--> sphenopalatine + submandibular ganglion -innervation 1. lacrimal gland +nasal glands 3. submandibular gland+ sublingual gland

sym superior mesenteric ganglion -innervation 2

-spinal levels -innervation 1. small intestine 2. colon

sym inferior mesenteric ganglion -innervation 4

-spinal levels -innervation 1. colon 2. kidney 3. bladder 4. sex organs

sympathetic ANS modes of innervation 3

1. Preganglionic neuron --> paravertebral ganglia--> synapses post-ganglionic neuron. 2. Preganglionic neuron--> specialized ganglia --> synapse with post-ganglionic fibers that go to target organs. -superior cervical ganglion - celiac ganglion -superior mesenteric - inferior mesenteric ganglia 3. Preganglionic neuron --> target organ. -adrenal medulla.

Post-synaptic modulations: withdrawal rebound hyperactivity MOA 3 examples for each

1. Proliferation of receptors= skeletal muscle -number of acetylcholine receptors increases 20 X or more after denervation -receptors spread out past endplate over the whole surface. 2. Loss of mechanisms for transmitter removal - loss of neuronal uptake of noradrenaline contributes substantially to denervation super sensitivity -at cholinergic synapses= a partial loss of cholinesterase occurs. 3. increased post junctional responsiveness -postsynaptic cells become supersensitive without a corresponding increase in the number of receptors. ex. SM cells become partly depolarized and hyper-excitable= adding to sensitivity

Anatomic output describe distribution and why

A preganglionic axon diverges to an average of 8 - 9 post ganglionic neurons. diffused and pains from visceral organs are therefore usually of dull nature and can manifest at different locations.

parasympathetic division 2 components

CRANIO-SACRAL 1. cranial outflow -preganglionic fibers in CNs - CN III = oculomotor -CNVII facial - CNIX glossopharyngeal nerve - CNX vagus nerve= thoracic + abdominal viscera ganglia lie scattered in close relation to the target organs. 2. sacral outflow -fibers --> nervi erigentes--> synapse in scattered pelvic ganglia--> short postganglionic fibers run to target tissues -bladder -rectum - genitalia.

Post-synaptic modulations: denervation supersensitivity -define -seen in what tissues

if a nerve is cut and its terminals are allowed to degenerate, the structure supplied by it becomes supersensitive to the transmitter substance released by the terminals. seen in skeletal muscle + blood vessels

enteric nervous system -describe location + structure -2 components -regulation

collection of nerve plexuses that surround the Gl tract -including the pancreas and biliary system. plexuses = system of ganglia sandwiches between the layers of the gut - connected by a dense meshwork of nerve fibers. 1. myenteric/ Auerbach's 2. submucosal or Meissner's plexus entirely peripheral receives input from the sympathetic and parasympathetic ANS BUT can function normally without extrinsic input from the sympathetic or parasympathetic division.

two neuron organization ANS pre and post synaptic neurons adrenal medulla -structure/ funciton -neurotransmitters released 4

exception to the two neuron organization CNS giant ganglion NO post ganglionic fibers -release neurotransmitters directly into bloodstream neurotransmitter released -epi -noepi -dopamine -peptides

submucosal or Meissner's plexus -location -controls

lies between the circular muscularis mucosae. This plexus controls ion and fluid transport. controls ion and fluid transport.

cotransmitters peptide Neuropeptide Y -location -function 2

location -post gang. sym neurons function -facilitates constrictor action of NE -inhibits NE release= neuromodulator

Dual innervation explain concept 2 exception

most organs receive both sympathetic and parasympathetic innervation. Actions of these organs are controlled by both systems. Exceptions: 1. ome organs/tissues receive only sympathetic innervation 2. sympathetic and parasympathetic systems produce similar rather than opposing effects. ex. salivary glands

cotransmitters def effect

neurons releasing more than one transmitter or modulator each interact with specific receptors + produces effects -often both pre- and post-synaptically.

Presynaptic modulation: heterotrophic interactions -define -explain what occurs in the myenteric plexus of the GI tract -explain what occurs in the heart

one neurotransmitter affects the release of another receptors on a presynaptic nerve ending that respond to a DIFFERENT neurotransmitter than the one secreted ex. myenteric plexus 1. epinephrine + norepinephrine released from sympathetic nerve terminals 2. inhibit release of ACh from the postganglionic parasympathetic nerve terminals. -Noradrenergic and cholinergic nerve terminals often lie close together in the myenteric plexus - opposing effects of the sym and parasystems from A. opposite effects of the two transmitters on the smooth muscle cells, B. from the inhibition of ACh release by E and NE acting on the parasympathetic nerve terminals. ex. heart -NE inhibits Ach release - Ach also inhibits NE release.

two neuron organization ANS pre and post synaptic neurons parasympathetic neurons + sympathetic neurons -length -neurotransmitter released

parasympathetic neurons 1. pre- synaptic= -long -neurotransmitter released=ACH 2. post synaptic= -short -neurotransmitter released= ACH -location= walls of visceral organs sympathetic neurons 1. presynaptic -short -neurotransmitter released= ACH 2. post synaptic -long -neurotransmitter released= A. epi/ norepi= cardiac + SM+ glands B. dopamine= renal vascular SM C. ACH = sweat glands -location= ganglion

enteric nervous system myenteric/ Auerbach's plexus -location -controls

plexus lies between the external longitudinal and the deeper circular smooth muscle layer. controls GI tract motility.

Presynaptic modulation: describe 2 types

presynaptic terminals releases neurotransmitter in response to AP often sensitive to transmitters+ other substances produced locally in tissues. effects most commonly act to inhibit transmitter release -sometimes enhance it 1. heterotrophic interactions 2. homotropic interactions

Post-synaptic modulations: withdrawal rebound hyperactivity -def -ex EXAM

same as concept as denervation supersensitivity long-term blockade of post-synaptic receptors --> increased response when the blocking agent is removed. ex. Patients treated chronically with some types of beta adrenergic receptor antagonists have rebound hypertension -sometimes to dangerous levels upon abrupt withdrawal of the agent.

ANS preganglionic neurons -type of fibers -diameter of fibers -conduction fibers

small diameter slower conduction b fibers

ANS response to stimulus

somatic NS= always excitatory ANS= excitatory OR inhibitory

sym celiac ganglion -innervation 4

spinal levels innervation -stomach -liver -pancreas -spleen

sym superior sympathetic ganglion -inneration 6

spinal levels innervation 1. pupillary dilator m 2. lacrimal gland 3. nasal glands 4. submandibular gland 5. sublingual gland 6. parotid gland

neuromodulator

substance that controls the production or release of another neurotransmitter

sym innervation post synaptic organ with muscarinic receptors EXAM

sweat glands

sympathetic ANS spinal levels

thoracolumbar T1-L3/4 + motor nuclei CNs

Presynaptic modulation: homotropic interactions describe ex. heart ex. brain

transmitter binds to presynaptic auto receptors and receptor on post synaptic membrane -affects the nerve terminals where it was being released. acts powerfully at noradrenergic nerve terminals. Ex. NE in heart muscle -released NE can inhibit further release by at least 90% -autoreceptor= alpha 2 -post synaptic receptor= b2 ex. brain -ACh release is modulated by effecting presynaptic muscarinic acetylcholine receptors -via alpha 2 receptors binding NE