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88 Cards in this Set

  • Front
  • Back
2 major morphological divsions of the NS:
1. CNS
2. PNS
What is the CNS composed of?
Brain + Spinal Cord
What is the PNS composed of? (3 things)
CNS fiber outflow
Sensory fiber inflow
Peripheral ganglia
What structures are found in the CNS?
-Cell bodies/major process of the Brain, Spinal Cord, and Interneurons
What structures are found in the PNS?
-Afferent neurons projecting into the CNS
-Efferent neurons projecting out of the CNS
2 Major FUNCTIONAL divisions of the PNS:
1. Somatic nervous system
2. Autonomic nervous system
What does Somatic mean?
That the somatic axons innervate skeletal muscle (either motor or sensory).
What does Autonomic mean?
That the axons innervate
-Smooth muscle
-Cardiac muscle
-GI neurons
Where somatic efferents/afferents cause changes in the external environment, what do Autonomic Efferents/afferents do?
Cause and sense changes in the body's internal environment
What is the ANS derived from?
Neural Crest
Does neural crest only give rise to the ANS?
Obviously no, it gives rise to many things.
What determines the fate of neural crest cells?
Their axial level
What does neural crest at the Cranial spinal cord level give rise to?
Parasympathetic ganglia
What does neural crest at the Vagal spinal cord level give rise to?
-Enteric ganglia
-Parasympathetic ganglia
-Superior cervical ganglion
What does neural crest at the Trunk spinal cord level give rise to?
-Sympathetic ganglia
-Adrenal medulla
What does neural crest at the Lumbosacral spinal cord level give rise to?
-Enteric ganglia
-Parasympathetic ganglia
3 divisions of the ANS:
What does the SNS function to do?
Equips the body for intense muscular action required in offense and defense
What does the PNS function to do?
Restore and conserve energy and give rest to vital organs.
What does the ENS function to do? (4 things)
1. Regulate enteric secretions
2. Renerate intestinal epithelium
3. Contract smooth muscles
4. GI motility
How is the ENS related to the PNS and SNS?
It can operate independently, but is modulated by SNS and PNS fibers.
At what spinal cord levels are SNS preganglionic neurons?
At what spinal cord levels are PNS preganglionic neurons?
-Brainstem nuclei
Where are the Enteric preganglionic neurons found?
In the walls of the gut
What is the cell column in the SC that houses SNS/PNS pregang. neurons?
Intermediolateral cell column
How are pre- and postganglionic neurons different in both the SNS and PNS?
Pre = myelinated
Post = unmyelinated
Where do preganglionic neurons synapse on postganglionics?
At clusters of cell bodies called GANGLIA
What type of ANS input do most organs recieve?
Input from both SNS and PNS, which is usually opposing.
What organs recieve parallel (both excitatory) input from the SNS and PNS?
Salivary glands
8 Responses included in a Sympathetic outflow increase:
-Increased heartrate
-Increased blood pressure
-Increased Cardiac output
-Diversion of bloodflow from skin to skeletal muscle
-pupil dilation
-Bronchiolar dilation
-Sphincter contraction
-Mobilization of fat/glycogen
How are ganglia of the SNS situated relative to the spinal cord?
Close to it and in chains
How are ganglia of the PNS situated relative to the spinal cord?
Far from it - ganglia are within or close to target organs.
4 Primary Things that happen during a PNS outflow increase:
-Reduced heartrate
-Reduced blood pressure
-Digestion/nutrient absorption
-Waste excretion
What is another name for the interomediolateral cell column that houses s2-S4 PNS neurons?
SPN - sacral parasympathetic nucleus
What is the effect of SNS vs PNS action on the Eye?
SNS = dilates pupil

PNS = constricts pupil
What is the effect of SNS vs PNS action on the Lacrimal gland?
PNS stimulates lacrimation
What is the effect of SNS vs PNS Salivary glands?
SNS = viscous secretion
PNS = watery secretion
What stimulates sweat glands?
What is the effect of SNS vs PNS action on the lungs??
SNS = bronchial relaxation

PNS = bronchoconstriction
How does the SNS affect Vascular smooth muscle? (Skin vs muscle)
Skin vessels = contracts
Muscle vessels = relax
How does the PNS affect all vascular smooth muscle?
What is the effect of SNS vs PNS action on the GI tract?
SNS: relax muscle walls, contract sphincters, decrease motility
PNS: opposite
What is the effect of SNS vs PNS action on the Bladder and Bladder Sphincter??
SNS: slight relaxation of the bladder, constricts sphincter.
PNS: contraction of bladder, relaxation of sphincter.
What is the effect of SNS vs PNS action on the penis and seminal vesicles?
SNS: ejaculation
PNS: erection
(point and shoot)
What efferents found exiting the spinal cord belong to the ANS?
ALL of them except those innervating skeletal muscle!
So what type of system is the ANS predominantly?
An efferent motor system of general Visceral Efferents - GVE
What are most of the GVAs concerned with?
Mediation of visceral sensation and regulation of vasomotor and respiratory reflexes - PNS
What GVA axons carry sensations from baro/chemoreceptors in the heart? To where?
cn IX and X - to the brainstem (NTS)
What carries GVA fibers from the gut to the CNS?
-Vagus nerves
-Splanchnic nerves
-Pelvic nerves
What carries pain fibers from blood vessels?
Somatic nerves
What happens once afferents from bloodvessels, heart and viscera reach the brain?
They elicit reflex responses through efferents.
General nature of ANS reflexes:
GVEs transmit impulses from ___ to ____:
From CNS to peripheral systems.
Where are visceral motor responses elicited?
In smooth muscle and glands
What is the main difference in the ANS compared to somatic in terms of how its targets are stimulated?
It uses 2 groups of neurons (SNS and PNS) instead of one.
Where are the Preganglionic neurons for the ANS housed?
in the CNS
Confirm whether the SNS chain ganglia are in the CNS or PNS
Where do preganglionics project to?
Ganglia (paravertebral, prevertebral, etc) where they synapse with postganglionics
Where do postganglionics go?
To the target organ
What are postganglionics called? Are they in the CNS or PNS?
Motor neurons - in the PNS; so autonomic ganglia lie in the peripheral NS too.
Where are the autonomic ganglia found?
-Sympathetic paravertebral chain
-Symp Collateral ganglia (prevertebral)
-Parasymp Intramural ganglion
Where are the cell bodies of SNS preganglionic neurons found?
In the intermediolateral horns of SC segments T1-L2
What is the special name for the spinal cord output from SNS at T1-L2?
Thoracolumbar outflow
Where do the paravertebral sympathetic chains extend?
From cervical to sacral SC levels - so longer than the actual cell bodies in the cord.
What is achieved by the sympathetic chains being longer than the levels of cell bodies?
Divergance - 1 cell body can give 10 postganglionic fibers, and these can reach other parts of the body.
What is the general configuration of the SNS pre and post fibers?
PRe = short
Post = long
Where do Preganglionic SNS fibers exit the spinal cord?
Out the ventral horn
Where do SNS preganglionics go after exiting the ventral horn?
To the mixed root, then branch off as white rami communicantes which can do one of 3 things.
What are the 3 alternatives available to white rami communicantes?
1. Synapse within the chain
2. Pass up or down to another level to synapse
3. Pass through and go to a prevertebral ganglion
What are the prevertebral nerves that pass thru without synapsing in the paravertebral chain?
Splanchnic nerves
What are gray rami for?
These are the unmyelinated postganglionic fibers that carry the nerve impulse from chain ganglion to target organ.
Where are white rami found? Where are gray rami found?
White: only T1-L2 levels
Gray: at every level
Why is the sympathetic chain longer than T1-L2?
So that it can give innervation to the head/neck/lower abdomen, not just the thorax.
What are the SC levels at which Splanchnic nerves originate?
Where do Splanchnic nerves synapse?
At the Celiac and Superior mesenteric ganglia
What carries postganglionics from the Celiac / Sup mesenteric ganglia to the target organs?
What spinal cord levels give rise to lower Splanchnic nerves that innervate the inferior mesenteric ganglion and hypogastric plexuses?
What is the special name for preganglionic parasymp outflow?
Where does the cranial and sacral PNS outflow originate?
Cranial: In the motor nuclei of cranial nerves 3, 7, 9, and 10

Sacral: in S2-S4
Where are the sacral outflow preganglionic PNS fibers' cell bodies housed? Where do they exit the spinal cord?
In the intermmediolateral cell column - exit via the ventral horn.
Where does the craniosacral PNS outflow go?
To the ganglion that is situated close to the target organ
So what is the general arrangement of the 2-neuron system for PNS outflow?
Pre = long
Post = short
What are autonomic plexuses?
Networks of nerves that redistribute SNS and PNS nerves
What does the hypogastric plexus innervate?
Most of the large intestine and abdominal and genital organs
What forms the Cardiac plexus?
-Cardiac sympathetic nerves
-Vagus nerve branches
What forms the Pulmonary plexus?
-Upper thoracic SNS nerves
-Vagus nerve branches
What forms the Celiac plexus?
-SNS fibers from celiac ganglia and thoracic aortic plexus
-PNS fibers from vagus via the esophageal plexus
You know about the enteric nervous system