L17 Fundams Of ANS Flashcards
LO2: desc diff paths via which S and PNS distrib their fibres to and from organs targets.
-most organs dual innerv S and PNS. Most effs are recip. Autonomic tone varies btw S and PNS-ongoing elec sig from ANS. Activat=tip bal. predom ANS tone determ by bal of output S and PNS. Sheath gl SNS drive only. Auton tone can differ btw L and R sides.
-S and PNS both 2 neuron chains:
1 in CNS- pre gang. SC/brainstem. Axons myelinated. White rami communicantes. Var axon length dep on ANS div. SNS SHORT PRE GANG!.
1 periph NS- post gang. Somatic outside CNS-from swells=ganglia. Axons not myel. Grey rami comm. SNS LOGN POST GANG!.
-SNS- pre gang flow out SC only. Nerve fibres have cell bod in T1-12 and L1-2. So thoracolumbar division of ANS. Transsec SC trauma= SNS probs.
Thoracic cord-dorsal and vent horns. White matter outs grey. Lat only at T1-L2 and S2-4, ev for auton outflow.
-lesion SC Sep brain contr S and PNS so not dual supply= auton disreflexia.
LO3: desc diff in overall func roles of S and PNS.
- SNS fight/flight. Exp predom in stress. Activ= expend energ. Blood to musc and heart. Incr HR and BP. Decr blood to GIT and skin.
- PNS- activ= decr HR, decr force contrac. Incr dig. Incr bod func eg bladd emp. Prom sleep.
LO4: outl func contr which S and PNS exert on targ organs.
- bladder- SNS spinal roots L1-2 supp destructor blood vess= full bladder, int sphincter close. PNS spinal roots S2-4=opp. If one fav over other=problems.
- overactive PNS clinic implics- BV dilat= shortage substr to brain. Eg due to infec.
- overactive SNS- BV constric= eg shortage substr to TOB eg extremity necrosis.
LO5: desc in detail the transmitters inv at syn and end organs of S and PNS.
-SNS all pre gang neurons in SC. leave immed and syn in paraverteb chain. Termin in sympath chain=redistrib sympath outflow- replic and sent to bod. Lesions of sympath chain/ pre gang= massive dam.
Pre gang neurons are cholinergic- exp Ach.
Post gang nicotinic Rs receive Ach.
Post gang are noradrenergic, some adrenergic (adren medulla).
Effector organs exp var Rs- alpha and beta.
-SNS outflow init restric then wide distrib-
3 poss modes termin:
Syn in chain at lev corresp to lev of ori (paraverteb). Then post gang sig to targ organ.
Syn at diff lev to ori-up or down chain.
May not syn in paraverteb chain (splanchnic nerves)- no syn, termin in gang rel to aorta supp gut- super and infer mesenteric gang. Trav as long as pre gang sympath neuron.
Grey rami unmyel, White myel.
-SNS eff sys assoc paraverteb chain. Maj syn immed after exciting cord. These termin in paraverteb chain=short pre gang fibres.
Contact post gang neurons, prod act. 3 modes termin (above).
-with 2 exceps (perspiration and ejaculation) sympath post gang fibres are noradrenergic. Neurons response for sweating=pseudomotor.
2 classes adrenoR- alpha and beta. Alpha exhibit alpha1/alpha 2 behav. Beta divs to beta 1/2/3. Both classes can exerc presyn inhib of other.
-sympath effs- pre gang short neurons cell bod in thoracolumbar cord. Pre gang sec Ach. Long post gang sec Na/adren.
-PNS- vagal outflow is maj. Post gang neuron in organ. Pre gang long and cholinergic. Post gang fibres short, in walls of effector organ, exp nicotinic Rs, are cholinergic. Effector organs exp muscarinic Rs.
-layouts of S and PNS allow flexib- nt’s, post syn Rs, poten for complexity.
-PNS outflow table.
-summ- all ANS pre gang fibres from CNS transm with Ach. All ANS gang bods have nicotinic Rs. Adren medulla behaves as gang-nicotinic Rs. All PNS effector organs have muscarinic Rs-blocked by atropine. Sweat glands and adjac Macy’s sympath exceps (cholinergic).
LO6: briefly acc for the imp of these transmitters in therap.
-imp for therap dev and s/e’s of curr therap. Cardiac ones v imp. Targ auton Rs.
LO7: comp and contr S and PNS.
- comm stand anat layout. Eq no synapses in series arr.
- diss detail of anat. Diff nt’s. Diffs=basis for therap.
LO1: somatic vs ANS
-somat NS- somat efferents-binary on/off. Vol. simp layout. 1 neuron carries output. Cell bod in SC or cranial loc. when X pit mater=periph NS. Eff neuron terminus direc on effector organ eg skel musc, activ to carry out task eg contrac. Inactiv rest of time. Motor tone exception. Inactiv dur REM excep eyes and resp.
Efferents under dev at birth. Prog by env, acq motor skill. Effs full dev by puberty.
-ANS- fundamental life funcs. Eg surv, prom sp, care offspring. Maint homeo. Contr func by changing contin output of 2 opp sys- S and PNS. Recip sys. Predom actions of ANS refl imbal in output of S and PNS.
-gen actions ANS-
Constancy- maint homeo, regul bod sys eg CVS, resp, dig, thermoreg. reflexes. Lesions in cervic SC disturb all.
Intermittent change in bias- prom excret mechs of bod when necess.
Effector organs- visc organs. Smooth musc, sec gls, cardiac musc.
Invol contr can somet be trained.
-overview ANS- always 2 neurons in series=relay sys. 1 has cell bod in CNS pre synap/gang, 1 in periph NS post syn driven by pre synaptic neuron and termin direc on effector. Exert action by 3 classes effector organ. Layout =lot flexib. (Diag).
LO5: PNS
-messages via cranial nerves brains and SC.
2 locat pre gang neurons- cranio sacral SC-
Cranial nerves most from brain- occulomotor 3, facial 7, glossophar 9, vagus 10. Cell bods and axons in nuc corresp to diff nerves.
Sacral SC levs S2,3,4. Lat horn fnd in T1-L2 and S2-4= Indic same pre gang auton neurons.
Cranio sacral divs of ANS.
LO1: give outl of anat of ANS (gen layout) and its div to sympath and parsympath parts.
Understand classif of NS based on function.
Disting btw somat and auton NS.
-NS can be split to:
CNS- glia and inter neurons, brain and SC. lies in cranium and vert col. Susp in CSF. Sophist funcs. SC segm nerves.
Periph NS- aff and eff fibres. Info btw CNS and either Rs or targ.
Cent and periph are continuum of same cell/sys/tiss, most neurons straddle. NOT indep.
-NS can also be split to:
Somatic NS cope with env. Skel musc only targ. Vol.
auton NS contr int env. Smooth and cardiac musc and glands as targs. Regul haemodynams, gut func etc. Most invol.
ANS is then func split to sympath and parsympath NS. Also enteric.
-afferent= conduc incoming sigs periph to CNS ie sensory neuron.
-efferent= conduc outgoing sigs from brain/SC to periph. Ie motor or autonomic neuron.
-ganglion= collec neuronal cell bods in periph NS.
-pre gang vs post gang neuron-
Pre=immed proxim to gang. Post= immed distal to gang.
-effector- targ organ exerts NS actions.
- can also split NS by reg: brain, SC, nerves.
- or by gross anat: grey matter cell bodies. White matter axons.
