Autonomic Flashcards
What is the general set up of neurons in autonomic nervous system as far as myelination of pre/post-ganglionic axons and the transmitter/receptor types?
Preganglionic myelinated axons use acetylcholine as their transmitter via ganglion type **(a3/B4) nicotinic receptors **
Then post-ganglionic unmyelinated axons which use either Ach or NE on corresponding cholinergic or adrenergic receptors
Where are sympathetic preganglionic neurons located?
From T1-L2 segments in lamina VII (7) forming the intermediolateral column
Interruption of supraspinal descending autonomic pathways above what level results in massive unpatterned reflex actication of sympathetic preganglionic neurons
Above T5 (about midway between T1-L2)
Sympathetic
Paravertebral ganglia innervate______
Prevertebral ganglia innervate ____
Paravertebral ganglia innervate all tissues and organs except those in the abdomen, pelvis, and perineum; prevertebral ganglia innervate the viscera and blood vessels of the abdomen and pelvis.
What is the primary neurotransmitter from sympathetic postganglionic nerves? What is the exception?
Norephinephrine
The exception is sympathetic ganglion neurons innervating the** sweat glands** which are cholinergic
Describe the impacts of norepinephrine and epinephrine on the following adrenoceptors:
a1 =
a1 = α1 receptors mediate excitation of the smooth muscle in blood vessels, iris (pupil dilator), vas deferens, bladder neck, and internal sphincter of the rectum.
Describe the impacts of norepinephrine and epinephrine on the following adrenoceptors:
a2 =
α2 receptors are located mostly in presynaptic terminals, and their main effect is presynaptic inhibition of the release of norepinephrine from sympathetic terminals (inhibitory autoreceptors) or other neurotransmitters from parasympathetic or afferent terminals
Describe the impacts of norepinephrine and epinephrine on the following adrenoceptors:
b1 =
β1 receptors are present in the heart and stimulate automatism of the sinus node, excitability of the His-Purkinje system, and contractility of the myocardium.
Describe the impacts of norepinephrine and epinephrine on the following adrenoceptors:
b2 =
the β2 receptors elicit smooth muscle relaxation, including vasodilation, bronchodilation, and relaxation of smooth muscle in the bladder and uterus
Describe the location of preganglionic parasympathetic neurons?
General visceral efferent column of the brainstem and at the sacral spinal cord segments S2-S4
Discuss the functional division of the parasympathetic system output?
1) cranial effectors
2) outputs mediated by vagus n. to thoracic and abdominal viscera
3) sacral preganglionic outputs to bladder, rectum, and sexual organs
What is the parasympathetic function of CN III?
Pupillary constriction and accomodation reflexes
What is the parasympathetic function of CN VII?
Pterygopalatine aka sphenopalatine ganglion to elicit LACRIMATION and cranial VASODILATION and to submaxillary and submandibular ganglia to elicit SALIVATION
What is the parasympathetic function of CN IX?
The glossopharyngial nerve innervates otic ganglion that promotes parotid gland SECRETION
What is the parasympathetic function of CN X?
Vagus nerve provides preganglionic innervation to autonomic ganglia in thorax and abdomen
Describe the division between vagal preganglionic neurons from the:
Dorsal motor nucleus of the vagus vs nucleus ambiguus
Preganglionic neurons from
Dorsal motor nucleus - innervate ganglia of cardiac, pulmonary, and enteric nervous system plexuses
Nucleus ambiguus - vagal output to cardiac ganglion neurons controlling the sinus node
Describe ACh muscarinic receptors in target organs:
M1
M2
M3
M1 - excitatory
M3 - excitatory - MOST of the excitatory effects of Ach on the visceral targets of parasympathetic neurons including smooth muscle contraction, exocrine gland secretion, endothelial synthesis or NO, and sweat gland
M2 - inhibatory - (presynaptic) -decrease automatism of sinus note and AV conduction
Besides ACh, what other neurotransmitters mediate the parasymathetic output?
Nitric oxide and vasoactive intestinal peptide
NO major mediator for cranial vasodilation and penile excretion
Name the pupil
Sympathetic receptor __
Parasympathetic receptor __
Sympathetic - dilation - a1
Parasympathetic - constriction and accomodation - M3
Salivary and lacrimal glands action/receptor:
Sympathetic
Parasympathetic
Sympathetic: inhibition via ?a2
Parasympathetic: stimulation via M3 and vasoactive intestinal polypeptide receptors
Heart action/receptor:
Sympathetic
Parasympathetic
Sympathetic - stimulation B1
Parasympathetic - Inhibition M2
Bronchi action/receptor:
Sympathetic
Parasympathetic
Sympathetic - dilation B2
Parasympathetic - Constriction M3
What is the etymology of adrenergic?
1930s from adrenaline + Greek -ergon ‘work’ + -ic.
Adrenaline = epinephrine
Describe skeletal muscle action/receptor
Sympathetic
Parasympathetic
Sympathetic - 2 actions -
constriction via a1
Dilation via b2
Parasympathetic - NA
Describe skin vessel action/receptor
Sympathetic
Parasympathetic
Sympathetic
constriction via a1
dilation? via NO?
Parasympathetic NA
Describe cranial nerve and visceral vessel action/receptor
Sympathetic
Parasympathetic
Sympathetic: constriction via a1
Parasympathetic: dilation via NO and vasoactive intestinal polypeptide
Describe sweat gland action/receptor
Sympathetic
Parasympathetic
Sympathetic: stimulation via M3
(** remember that this is an exception to the rule, only cholinergic sympathetic neurons in the system)
Parasympathetic: NA
GI motility action/receptor
Sympathetic: inhibition (B2)
Parasympathetic: contraction (M3) and relaxation (NO, VIP)
GI secretion action/receptor
Sympathetic: inhibition a2
Parasympathetic: gastric acid secretion (M1), intestinal secretion (M3, VIP)
Bladder detruser action/receptor
Sympathetic
Parasympathetic
Sympathetic: inhibition b2, b3
Parasympathetic: stimulation M3
Bladder neck action/receptor
Sympathetic: stimulation a1
Parasympathetic: inhibition NO
Rectal smooth muscle action/receptor
Sympathetic: inhibition b2
Parasympathetic: stimulation M3
Erectile tissue action/receptor
Sympathetic: constriction a1
Parasympathetic: dilation NO
Vas deferens action/receptor
Sympathetic: contraction a1
Parasympathetic: NA
What is the receptor which forms the relay between central and peripheral components of the autonomic nervours system?
a3/b4 nicotinic ganglionic receptor
this is important as there can be conditions of autoimmunity targeting the nicotinic ganglionic acetylcholine receptor (autoantibody α3-AChR Ab) which causes autoimmune dysautonomia that is either subacute or insidious in onset
What is the receptor which forms the relay between central and peripheral components of the autonomic nervours system?
a3/b4 nicotinic ganglionic receptor
this is important as there can be conditions of autoimmunity targeting the nicotinic ganglionic acetylcholine receptor (autoantibody α3-AChR Ab) which causes autoimmune dysautonomia that is either subacute or insidious in onset
What is the normal SBP, DBP, and HR response to standing?
In rseponse to standing baroreflex is activated and:
Systolic blood pressure falls 5-10 mmHg
Diastolic blood pressure rises 5-10 mmHg
Heart rate rises 10-20 beats/min
Definition of orthostatic blood hypotension
sustained drop in blood pressure of:
at least 20 mm Hg systolic and/or 10 mm Hg diastolic that occurs within 3 minutes of active standing or head-up tilt
during tilt table testing sometimes more strict criteria (30mmHg systolic or 15 mmHg diastolic) is used as the passive maneuver of tilt testing doesn’t activate lower limb “muscle pump” thus more blood pooling in lower limbs
General definition of Postural Tachycardia Syndrome
a disorder in which patients frequently experience symptoms of orthostatic intolerance in response to postural stressors despite autonomic reflexes that are generally preserved
The hallmark of the disorder is an excessive rise in HEART RATE in response to standing; however, unlike in classic autonomic failure, blood pressure does not fall.
Diagnostic criteria of POTS
POTS is defined as a symptomatic and sustained heart rate increment of 30 beats/min or more within 10 minutes of standing or head-up tilt in the absence of orthostatic hypotension; the standing heart rate is often 120 beats/min or higher.4 For individuals 12 to 19 years of age, the required increment is at least 40 beats/min.5
Definition of orthostatic intolerance
Orthostatic intolerance, then, is the inability to tolerate upright posture because of symptoms of cerebral hypoperfusion or sympathetic activation, or both, which are relieved with recumbency.
What is the ratio of women:men with POTS?
5:1
