Nervous System Flashcards
Are visceral Afferent neurons motor or sensory neurons?
Which direction do they carry information?
Afferent = sensory
Carry info TO the CNS from viscera
= pain, stretch, distention, chemo and baro receptors (poorly localized)
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Are visceral Efferent neurons motor or sensory neurons?
Which direction do they carry information?
Efferent = motor (visceromotor)
Carry info from CNS to viscera
Innervates smooth and cardiac muscle and gland cells
Does the Visceral Afferent or Visceral Efferent neurons form the ANS?
Visceral Efferent
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What are the 2 types of Visceral Efferent neurons?
Somatic efferent and Visceral efferent
What is the major difference b/t somatic efferent neurons and somatic visceral neurons?
Somatic efferent neurons have only one neuron b/t the CNS and effector cell; The neuron soma is always in CNS.
Visceral efferent neurons have 2 neurons b/t CNS and effector cell (pre and post ganglionic); only the preganglionic soma is in CNS (34)
Where do sympathetic fibers exit CNS?
Where do parasympathetic fibers exit CNS?
Sympathetic = T1-L2 (thoracolumbar)
Parasympathetic = S2,3,4 and CN III, VII, IX, X (craniosacral)
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Where are preganglionic sympathetic cell bodies located?
Gray matter of the Lateral Horn T1-L2
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Where are postganglionic sympathetic cell bodies located?
Paravertebral ganglia (make up sympathetic trunk) Prevertebral ganglia (near organs)
How many paravertebral ganglia are typically present?
22-23 2-3 cervical 12 thoracic 4 lumbar 4 sacral
How do virtually all spinal nerves connect to the sympathetic trunk?
Gray rami communicantes
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Describe the sympathetic innervation to the head and neck structures.
Preganglionic sympathetic fibers enter chain through white rami communicantes of T1-T5 spinal nerves, ascend, and terminate on postganglionic neurons of cervical chain ganglia
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The superior cervical chain ganglion is made up of postganglionic axons at what cervical level?
Middle?
Inferior?
Superior = C1-C3/4 cervical spinal nerves Middle = C4-6 Inferior = C7-8
Where are prevertebral ganglia found?
Near organs they supply
*Include postganglionic sympathetic neurons
**The axons of these neurons are distributed primarily via arterial plexuses to effector cells
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How are postganglionic neurons of the prevertebral ganglion innervated?
Innervated by preganglionic sympathetic neurons whose fibers traverse through the sympathetic trunk w/out synapse and travel through splanchnic nerves to the specific ganglia
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Where is the celiac ganglion?
What does it innervate?
Celiac ganglion found near celiac artery
Innervates foregut and midgut
Receives preganglionic fibers from greater splanchnic nerves
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Where is the superior mesenteric and aorticorenal ganglia?
Where do they innervate?
Near superior mesenteric and renal arteries
Innervate midgut
Receive preganglionic fibers from lesser splanchnic nerves
Where is the inferior mesenteric ganglion?
What does it innervate?
Near inferior mesenteric artery
Innervate hindgut
Receives preganglionic fibers from lumbar splanchnic nerves
Describe the functions of the sympathetic division of ANS as it relates to 1) cutaneous structures (arteries of skin, sweat glands, arrector pili muscles)
2) Arteries of skeletal muscle
3) Pupils
4) heart rate/blood pressure
1) Vasoconstrict arteries of skin, increase sweat gland secretion, activate arrector pili
2) Vasodilate arteries in skeletal muscle
3) Dilate pupils
4) Increase heart rate and blood pressure
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Where are preganglionic parasympathetic neuron cell bodies located?
Brain-exit via CN III, VII, IX, X
and spinal cord-exit via spinal nerves S2,3,4
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Are preganglionic parasympathetic axons myelenated?
Yes
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Where are postganglionic parasympathetic neuron cell bodies located?
Parasympathetic ganglia = near/in the wall of organs they innervate
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How many pairs of parasympathtic ganglia are there? What are they?
Four parasympathetic ganglia
1) Ciliary - receives preganglionic fibers from CN III
2) Submandibular - receives preganglionic fibers from CN VII
3) Sphenopalatine - receives preganglionic fibers from CN VII
4) Otic - receives preganglionic fibers from CN IX
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What type of neurons are found in Auerbach’s plexus (smooth muscle of GI tract); Meissner’s (submucosal plexus); Cardiac plexus; Pulmonary plexus; Pelvic plexus?
Postganglionic Parasympathetic fibers. These are all examples of intramural ganglia
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Where are preganglioinic fibers to intramural ganglia from?
CN X and spinal nerves S2,3,4
Are postganglionic parasympathetic axons myelenated?
No
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Describe functions of the Parasympathetic Nervous System as it relates to:
1) Heart rate/blood pressure
2) Glands of digestion
3) Peristalsis of the gut
4) Pupils
1) Decrease HR and BP
2) Increase glands of digestion (salivary/GI)
3) Increase peristalsis of the gut
4) Constrict pupils
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Visceral pain afferent fibers enter the spinal cord through what spinal nerves?
T1-L2
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Visceral physiological (chemoreception, baroreception, distention) afferent fibers enter the spinal cord through…?
CN IX, X and S2,3,4
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