3 Flashcards
General Model of SNS:
- Motor output to the sympathetic nervous system descends from the brain OR input from afferents (from the body) synapses on neurons in the intermediolateral cell column (gray matter) - Located from T1 – L3
- SNS neurons send efferent axons through the white rami communicantes to a paravertebral ganglion
- Within the paravertebral ganglion, the axon can:
- Option 1: Synapse within the paravertebral ganglion at that spinal level
- Option 2: Continue to another paravertebral ganglion at a different spinal level and synapse there
- Option 3: Pass through the paravertebral ganglion and continue to a prevertebral ganglion (through a splanchnic nerve) and synapse there
Solid lines = efferents from spinal cord to _________
1st ganglion
- pre-gangionic fibre
Dotted lines = efferents from gangion to ___
target organ
- post-ganglionic fibre
Where is the intermediolateral horn/column found?
Found in lamina VII of the thoracic and upper lumbar spinal cord
T/F: The descending pathways that influence neurons in intermediolateral horn/column are diffuse and hard to distinguish
True
Reflex pathways from afferents also impact the activity of neurons in which column?
intermediolateral horn/column
Option 1: Neuron in the intermediolateral horn (pre-ganglionic neuron) –> synapses on a neuron in the paravertebral ganglion at that __ spinal level
same
Option 1: Axon travels through the __ __ __, synapses on the post-ganglionic neuron
white rami communicantes
T/F: White rami communicantes are myelinated
True
Option 1: The postganglionic neuron sends efferents out to __ __
visceral organs
T/F: Gray rami communicantes are myelinated
False, unmyelinated
Option 1: Gray rami communicantes (unmyelinated fibres) join the __ __
spinal nerve
What are sympathetic inputs of option 1 of the SNS?
- skin, blood vessels, heart, and lungs at that spinal level
Option 2: Where do the cervical ganglia recieve fibers from?
Upper thoracic intermediolateral horn:
- Superior cervical ganglion – around the level of C1 – C4
- Middle cervical ganglion C5-C6
- Inferior cervical ganglion C7-C8
Option 2: Neuron in the intermediolateral horn (pre-ganglionic neuron) –> synapses on a neuron in a paravertebral ganglion at a __ spinal level
different
Option 2: The inferior cervical ganglion fuses with fibres from the first thoracic ganglion to form the __ __
stellate ganglion
Option 2: Superior cervical ganglion – SNS input to the __ __
cranial nerves
Option 2: nerves travel along blood vessels and often join the parasympathetic fibres of __ __
cranial nerves
Option 2: Which cranial nerves does the superior cervical ganglion house?
CNs III, VIII, IX, X
Option 2: Middle + stellate – SNS input to:
- heart
- trachea, bronchi, bronchioles
The __ and __ receive inputs from “Option 1” and “Option 2” gray ramii, forming web-like cardiac and pulmonary plexuses that innervate these structures
heart; lungs
Option 2: Long ciliary nerves –> SNS input to pupil causing? Accompanies by?
- pupillary dilation
- accompany short ciliary nerves (CN III)
Option 2: T/F: SNS input tends to make tears, saliva less “watery”, more “mucus-y”
True
Option 2: The SNS inputs tend to accompany the cranial nerves at some point along their course, which cranial nerves?
CN VII, IX
Option 3: Neuron in the intermediolateral horn –> passes through the paravertebral ganglion (no synapse) –> synapses on a ___ __
pre-vertebral ganglion
Option 3: The __ __ form nerves on the way to the prevertebral ganglion
white ramii
Option 3: greater splanchnic nerve –> __ __ (T5 – T9)
celiac ganglion
Option 3: lesser splanchnic nerve –> __ __ __, __ __ (T10 – T11)
superior mesenteric ganglia, aorticorenal ganglia
least splanchnic nerve –> __ __ (T12)
renal plexus/ganglia
lumbar & sacral splanchnic nerves –> __ __ __, plexuses to pelvic and lower abdominal organs (L1 – L2)
inferior mesenteric ganglia
Option 3: What is the celiac ganglion responsible for?
pancreas, liver
Option 3: What is the aorticorenal ganglia responsible for?
- kidney
- gonad
- suprarenal gland
Option 3: What is the superior mesenteric ganglion responsible for?
- ascending colon
- transverse colon
- small intestine
Option 3: What is the inferior mesenteric ganglion responsible for?
- descending colon
Compare and contrast SNS & PNS
Sympathetic nervous system
- short pre-ganglionic fibres, longer post-ganglionic fibres
- Neuronal cell bodies in the intermediolateral horn of T1 – L3
- Ganglia can be paravertebral or prevertebral
- Pre-ganglionic fibres can be white rami communicantes from the spinal cord or splanchnic nerves
Parasympathetic nervous system
- Long pre-ganglionic fibres, short post-ganglionic fibres
- Neuronal cell bodies in the brainstem (cranial nerve nuclei) or sacral spinal levels
- No prevertebral or postvertebral ganglia
T/F: Parasympathetic nervous system is cranial nerve and sympathetic nervous system is spinal nerves (but can combine with cranial nerves)
True
Edinger-Westphal nucleus (midbrain) –> ciliary ganglion –> causing pupillary constriction
CN III
Superior salvitory nucleus (pons) –> sphenopalatine –> lacrimal gland, nasal mucous secretions
CN VIII
superior salivatory nucleus (pons) –> submandibular ganglion –> sublingual, submaxillary salivary glands
CN VIII
inferior salivatory nucleus (medulla) –> otic ganglion –> parotid salivary glands
CN IX
Salivary & lacrimal secretion is mainly under control of which nervous system?
parasympathetic nervous system control
T/F: PNS causes more saliva, more watery, more digestive enzymes
True
T/F: SNS causes less fluid, more “sticky”
True
What is the cranial nerve responsible for most of parasympathetic nervous output?
vagus
What nucleus is associated with the vagus nerve?
dorsal motor nucleus of the vagus
What is the pathway of the vagus nerve?
- Longest course of any cranial nerve – leaves through jugular foramen and descends alongside the carotid arteries
- Forms anterior and posterior trunks at the stomach and divides to supply plexuses in the abdominal cavity, all the way to the left (distal) colon
Where are the bodies of the parasympathetic sacral efferents found?
S2-S4
What do the parasympathetic sacral efferents travel with?
pelvic splanchnic nerves
What does the parasympathetic sacral efferent supply?
- rectum
- bladder
- male & female reproductive organs
Fill in the blocked out spots
intermediolateral column, T1-L3
pre vertebral & paravertebral
brainstem nuclei & sacral segments
small ganglia in walls of viscera
What is the main neuro-transmitter & main receptor of SNS preganglionic?
- acetylcholine
- nicotinic
What is the main neuro-transmitter & main receptor of SNS postganglionic?
- norepinpehrine (+ epinphrine in adrenal medulla)
- adrenergic, alpha + beta
What is the main neurotransmitter & main receptor of PaNS preganglionic?
- acetylcholine
- nicotinic
What is the main neurotransmitter & main receptor of PaNS postganglionic?
- acetylcholine
- muscarinic (acetylcholine)
What are exceptions to SNS postganglionic neurotransmission?
- Acetylcholine in skin
- Adrenal glands don’t have post-ganglionic innervation… they “are” the ganglion
When is acetylcholine used in SNS postganglionic neurotransmission?
- sweat glands (muscarinic)
Where does the parasympathetic nervous system have impact on blood vessels?
- the GI system
- the reproductive system
Where is acetylcholine synthesized & stored?
Acetylcholine is synthesized in presynaptic nerve terminals and then stored in vesicles
- Reaction:
Acetyl-CoA + Choline —————-> Acetylcholine
Enzyme: choline acetyltransferase
After acetylcholine is secreted into the synapse it is degraded by what?
acetylcholinesterase
What is acetylcholine degraded to?
acetate and choline (choline is taken back up into the presynaptic terminal)
Where is acetylcholinesterase distributed?
Acetylcholinesterase is widely distributed in connective tissue throughout the body and in the synapse of cholinergic terminals
How is norepinephrine synthesized?
Outside the vesicle:
- Tyrosine ———————> Dopa (hydroxylation)
- Dopa ————————-> Dopamine (decarboxylation)
Then, dopamine is transported into the synaptic vesicle:
- Dopamine ——————-> Norepinephrine (hydroxylation)
In the adrenal medulla, most norepinephrine is converted into epinephrine through methylation (in the vesicle)
- Norepinephrine ————> Epinephrine (methylation)
hormones made by adrenal glands
caetcholamines
__-__% of secreted norepinephrine is taken up again into the presynaptic terminal
50 – 80
How is epinephrine taken back up?
secreted into the bloodstream by the adrenal medulla (endocrine)
__ can be broken down by monoamine oxidase near the synapse and catechol-O-methyl-transferase (COMT)
Norepinephrine
Both the parasympathetic (__) and sympathetic (__) outputs are important for pupillay size
However, focusing the lens is mostly under control of the __ system
constriction; dilation; parasympathetic
Nasal, lacrimal, salivary, gastrointestinal glands:
Strongly stimulated by __ activity – lots of watery secretions that are rich in enzymes (when enzymes apply)
Glandular secretion can also be stimulated by the __ – less watery, therefore usually lower rate of secretion
The glands of the intestines are less controlled by the ___, more by the food in the lumen of the gut
parasympathetic; sympathetic; autonomic NS
Sweat glands: stimulated by the __ – however, the neurotransmitter secreted is __
sympathetic nervous system; acetylcholine
Blood vessels:
__ nervous system – vasoconstriction in most vascular beds – mediated by alpha-1 receptors - Vasodilation in others mediated by __ in skeletal muscles, heart, liver
__ nervous system – very limited effect on any blood vessels outside the GI tract and reproductive organs
Sympathetic; beta-2 receptors; Parasympathetic
Heart:
__ nervous system – beta-1 receptors increase contractility (basically, force of contraction) and heart rate –> increased cardiac output
__ – muscarinic receptors decrease heart rate but have a small (negative) influence on contractility
Sympathetic; Parasympathetic
Glucose metabolism:
No role for the __ nervous system
Gluconeogenesis, glycogenolysis, hyperglycemia with __ nervous system stimulation
parasympathetic; sympathetic
The parasympathetic nervous system usually causes __, __ responses
specific localized
The sympathetic nervous system can participate in specific, localized responses as well – the usual day-to-day function of the SNS + overwhelmingly activated (mass discharge) to accomplish the “__ _ __” response
fight or flight
Major reflexes include:
Baroreceptor reflex
- __ – baroreceptors from CNs IX and X
- __ – parasympathetic and sympathetic CN X, thoracic plexus
GI reflexes mediated by sensing food (whether sight/taste/smell or presence of food/secretions in the lumen)
- __ – visceral receptors from CN X
- __ – CN X
Micturition (urination) reflex
- afferents & efferents at the level of the __ __ __
afferent; efferent
afferent; efferent
sacral spinal cord
__ __ __ in the medulla receives input from the afferents, sends output to a wide variety of other brain areas
Nucleus tractus solitarius
Prevention of storage in the NT vesicle
Reserpine – blocks VMAT –> depletion of catecholamines, increase or decrease in catecholamine transmission?
decrease
Non-vesicle-mediated “leakage” of neurotransmitter from the presynaptic terminal
Amphetamine, tyramine, increase or decrease in catecholamine transmission?
increase
Inhibition of reuptake at the presynaptic terminal
Cocaine, selective norepinephrine reuptake inhibitors (i.e. Effexor)
Increase or decrease in catecholamine transmission?
increase
Inhibition of NT degradation
Mono-amine oxidase inhibitors (tranylcypromine)
Increase or decrease in catecholamine transmission?
Increase
Inhibition of NT release due to auto-receptor activation
Clonidine thought to be a major example
Increase or decrease in catecholamine transmission?
Decrease
a substance that activates a receptor when it binds to it
agonist
a substance that binds to a receptor but doesn’t activate it fully
partial agonist
a substance that inactivates a receptor or enzyme when it binds to it
antagonist
T/F: Antagonist can be reversible & irreversible
True
Alpha and beta receptors have different __ for different agonists and antagonists
affinities
beta receptors have a high affinity for __, but alpha receptors have a negligible affinity. __ is therefore a selective beta-agonist
isoproterenol
Beta-1 receptors have a high affinity for __, but beta-2 receptors don’t. __ is therefore a selective beta-1 antagonist
metoprolol
Phenylephrine
- Selective agonist for __ receptors
- Main indication is as an over-the-counter __ - Causes vasoconstriction and decreased secretions from the nasal mucosa
- Can also be used IV (emergently) to increase __ __
- alpha-1
- decongestant
- blood pressure
Clonidine
- Selective __ agonist - Acts on presynaptic terminals to reduce __ transmission in the central nervous system
- Main indication is as an __ – reduction of sympathetic nervous system activity
- alpha-2
- adrenergic
- antihypertensive
Isoproteronol – activates __ and __ receptors
Dobutamine – activates __ receptors with less __ receptor effect
Both increase cardiac output… but dobutamine will increase blood pressure the most
Why would this be?
beta-1; beta-2
beta-1; beta-2
Increase HR –> increases contractility –> increases SV
Albuterol, salbutamol are inhaled selective __ agonists
Activate __ receptors in the bronchioles
beta-2; beta-2
