Autonomic NS Flashcards
Nucleus Tractus Solaritus
- in dorsalmedial caudal medulla; gets all visceral afferents
Role of Reticular Formation
Reticular formation neurons then integrate info from hypothalamus, NTS, etc and regulated sympathetic and parasympathetic outflow
Sympathetic Basics
- Thoracolumbar - cell bodies in intermediate horn of thoracic and upper lumbar SC
- Short pre-ganglionic cell w/ body in interomediolateral cell column —> spinal nerve —> through white ramus —> sympathetic chain ganglia (post-synaptic cell body)
- 1- synapse on chain ganglia it enters
- 2- move up or down chain and synapse on another ganglia in sympathetic chain
- 3- pass through chain w/o synapsing and synapse on pre-vertebral ganglia
- Celiac, superior mesenteric, inferior mesenteric
**Adrenal medulla - pre-ganglionic fibers pass w/o synapsing through sympathetic chain and synapse right on adrenal gland —> epinephrine/NE into blood stream
- Pre-ganglionic releases Ach onto nicotinic receptor
- Post-ganglionic release NE onto alpha or beta receptors
Parasympathetic Basics
- Craniosacral - cell bodies in CN ganglia (3, 7, 9, 10) or sacral SC
- Long pre-ganglionic axon then synapses on post-ganglionic cell embedded in target organ
- Pre-ganglionic releases Ach onto nicotinic receptors
- Post-ganglionic releases Ach onto muscarinic receptors (mult subtypes)
- **HUGE effect on GI contraction
How does Viagra work? Side Effects?
- NO causes vasodilation (produced by endothelial cells then diffuses into smooth muscle —> relaxation)
- NO —> activates guanylyl cyclase —> inc cGMP —> ATPase pumps Ca++ out —> relaxation
- Viagra (Sildenafil) inhibits phosphodiesterase (PDE5) which normally degrades cGMP in corpus cavernosum; so only works if sexual stimulated to begin with
- Mild side effects b/c effect on other phosphodiesterase (ex - PDE6 in retina —> color vision abnormalities)
Which 4 CN have parasympathetic outflow?
Oculumotor Nerve (III) - Ciliary musc (accommodation) Sphincter of Pupil (constrict pupil- dilates)
Facial Nerve (VII) -Lacrimal gland (tears) Nasal glands (mucus) Palatine glands (mucus) Submandibular gland, sublingual gland, lingual glands (saliva)
Glossopharyngeal Nerve (IX)- Parotid gland (salivation)
Vagus (X) - All thoracic and abdominal viscera (heart, lungs, esophagus, stomach, SI, proximal colon, pancreas, upper ureters)
Alpha 1 (affinity & effects)
NE»_space; epi
- Constrict arterioles (skin, mucosa, skeletal muscles, veins)
- Contract radial muscle of pupil (widens it)
- Dec bronchial gland secretions (NE)
- Inc secretion of sweat glands of palms and feet
**-Parasympathetic contracts sphincter of pupil to close it
BUT no parasympathetic control on arteriole or vein pressure
Alpha 2 (affinity & effects)
NE»_space; epi
-Constrict arterioles (skin, mucosa, skeletal muscles, veins)
**-NO parasympathetic control of arteriole or vein pressure
Beta 1 (affinity & effects)
NE = epi
-Inc HR and inc contractility
**-Parasympathetic can combat by dec HR BUT no parasympathetic control of contractility
Beta 2 (affinity & effects)
Epi»_space; NE
- Dilation of coronary arteries, arterioles to skeletal muscles, arterioles to abdominal viscera
- Relax ciliary muscle to flatten lens for far vision
- Relax bronchiole muscles and inc bronchial gland secretions (epi)
- Inc contractility of skeletal muscle
- *-Parasympathetic does not control vessels and NO parasympathetic effect on skeletal muscle contractility
- Parasympathetic does combat by contracting ciliary muscle making lens more convex AND contraction of bronchiole muscles and inc secretions (protective if something in lungs)
Pupil Constriction Path v Pupil Dilation Path
- Parasympathetic v Sympathetic
- Parasymp - pupil constriction; EWN —> ciliary ganglion —> short ciliary fiber to iris
- Symp - pupil dilation; hypothalamus —> interomediolateral of C8-T2 —> superior cervical ganglion —> follow carotid artery to eye for dilator & superior tarsal muscle
Anisocoria
asymmetry in pupil size; 20% of normal ppl
How does pupillary light reflex work?
Light signal —> optic tract —> pre-tectal nucleus —>synapses on BOTH EWN —> both direct & consensus reflex
2 Poss Causes of Pinpoint Pupils
pontine lesions (block symp but not parasymp) OR narcotic use
Argyll Robertson Pupil
seen in late syphilis; small pupils that react to light but not accommodation
Adie’s Pupil (+ pharm test)
- degeneration of ciliary ganglia —> “tonic pupil” (taks long time to move)
- Pharm Test- give pilocaprine (parasymp mimetic) and if constriction it confirms dx
4 Poss Causes of Horner’s + Pharm Test
- Causes can be at any point of sympathetic tract …
- Brainstem (part of lateral medially system)
- Lateral horns of C8-T2 or superior cervical ganglion
- Pancoast tumor at top of lung can compress as it travels w/ carotid
- Carotid artery lesions - if b/f bifurcation then includes sweat glands (anhydrosis) but id ABOVE bifurcation then sweating fine
- Pharm Test - use apraclonidine (alpha agonist) which should reverse miosis; de-nervated muscles are more sensitive to drugs
Bladder Afferents & Efferents
- Afferents
- Stretching of depressor —> A delta —> sacral SC (b/c parasymp control)
- Bladder neck & internal sphincter —> thoracic SC (b/c symp control)
- Efferents
- Interomediolateral sacral SC —> detrussor (para-symp)
- Sacral gray matter (Onuf’s nucleus) —> external sphincter (VOL CONTROL)
- Interomediolateral thoracic SC —> bladder neck and internal sphincter (symp)
Descending Bladder Control + Reflex
- Descending Control - integration in aquaductal grey —> pontine micturition center —> efferents
- “Reflex” - stretch (A delta) —> sacral SC —> contract detrussor
Sequence of Micturition
- Voluntarily relax perineum
- Inc tension of abdominal wall
- Slow contraction of detrussor
- Associated opening of internal sphincter
- Voluntary relaxation of external sphincter
4 Bladder Problems
- Hyperactive detrussor- disrupt descending inhibitory fibers (inc urgency, nocturia, urge incontinence, inc frequency)
- Dyssynergia - incomplete emptying and prone to UTIs b/c disconnect b/n detrussor and sphincter relaxation
- Urinary retention - PAINFUL; SC lesions, BPA, transverse myelitis, etc; pre-disposed to UTIs
- Sensory Bladder - neuropathy of bladder afferents or SC lesion; not painful b/c no A delta afferents but also predisposed to UTIs
Bethanechol
can produce bladder contractions in a flaccid bladder. This is generally disappointing clinically
How to treat spastic bladder
oxybuytinin
Terazosin and Doxazosin
can relax urinary sphincters and may be useful in dyssynergia, and in prostatic hypertrophy
