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
