Autonomic Nervous System Flashcards
Where are all neuronal cell bodies found and why?
In the CNS or near it (none in arms and legs): better protected
Define Neurolemma
The nuclei and cytoplasm of Schwann cells wrapped around the outside of the myelin sheath
Define Ganglia, nuclei, nerves, and tracts (and the difference between them)
Ganglia: collection of nerve cell bodies in the PNS
-Nerves: collection of axons in the PNS
Nuclei: collection of nerve cell bodies in the CNS
-Tracts: collection of axons in the CNS
Dorsal Roots
Contains sensory information (afferent impulses)
-posterior part of spinal cord
Ventral Roots
-Motor (efferent nerves)
-Anterior part of spinal cord
-Gray matter of spinal cord (cell bodies)
-white matter is axons
Nervous System divisions
CNS
-brain
-spinal cord
PNS
-Cranial Nerves
-Spinal Nerves
-somatic
-ANS
PNS divisions
somatic (voluntary): carries info to the skeletal muscles
Autonomic (visceral, involuntary): supplies smooth muscles, glands, and conducting system of the heart
Somatic vs ANS (how many neurons transmit messages?)
Somatic efferent impulses utilize a single neuron to transmit info from CNS to skeletal muscle
symp and parasymp efferent information is transmitted through 2 neurons
-Preganglionic and postganglionic (very specific to ANS)
Somatic sensory info:
touch, pain, temp, proprioception
motor fibers: innervate muscle fibers, controls VOLUNTARY movement
Where are cell bodies located for preganglionic and postganglionic neurons?
Preganglionic: CNS
Postganglionic: autonomic ganglion (ends at target organ)
-whether parasympathetic or sympathetic, preganglionic neuron originates in CNS
-where it ends depends on symp or parasymp
Where along the spine do sympethetic preganglionic neurons originate?
Lateral!! horn of thoracolumbar!! spinal cord (T1-L3)
Through where do preganglionic axons exit the spinal cord?
Ventral (anterior) roots
Preganglionic and postganglionic neuron lengths: sympathetic vs parasympathetic
Sympathetic: pre = short, post = long
-pregang neurons go to the paravertebral ganglia chain (22 pairs)
parasympathetic: pre = long, post = short
-Preganglionic neurons go to ganglions located on or near target organs
sympathetic preganglionic fibers: routes to synapse with postganglionic neuron (paravertebral ganglionic chain)
1: enter and immediately synapse with postgang in paravert ganglion at its respective vertebral level
2: pass through and ascend before synapsing
3: pass through and descend before synapsing
4: pass through the paravertebral ganglia without synapsing and continue via splanchnic nerves to the PREvertebral ganglia anterior to the AORTA and synapse there
-celiac, superior/inferior ganglia
Prevertebral aortic ganglia
-Just know this is an option of where neurons could go, not all will go to ganglionic chain
-A MAJORITY of sympathetic preganglionic neurons are SHORT and go to the paravertebral area
Sympathetic postganglionic neurons
-enter the gray rami and re-enter and travel along the spinal nerves to the target organ
-gray rami: essentially houses pre and postganglionic neurons I guess
Which cranial nerves have preganglionic cell bodies from the parasympathetic system? Where on the vertebrae?
-CN III, VII, X, IX
-S2-S4 (craniosacral!!!)
-innervate pelvic viscera and some abdominal structures
-innervate smooth muscle in the eye (CN III), salivary glands and lacrimal glands (CN VII)
-Vagus nerve carries 80% of parasympathetic nerves
-Gray matter of brainstem
Clarification: This slide is describing where parasympathetic neurons originate, being in the brain as well as sacral region of the vertebrae (Vagus literally innervates most major organs involved in parasympathetic responses involved in important processes of homeostasis)
Which nerves have their parasympathetic ganglia located directly in their target organs?
Vagus nerve: heart, lungs, liver, esophagus, most of GI tract up to transverse colon
pelvic splanchnic nerves (S2, S3, S4): reproductive organs and bladder
CN III, CN VII, CN IX (not X)
-Synapse in cranial ganglia near target organ
-oculomotor: Ganglia located behind the eyes, innervating pupil
-Facial: innervates the sublingual and submandibular salivary glands, lacrimal glands, and glands in nasal cavity
-Glossopharyngeal: innervating the parotid salivary gland
Which neurotransmitter is released by ALL preganglionic neurons?
Ach (Cholinergic)
-cholinergic:
-nicotinic
-muscarinic
Acetylcholine binds to what receptors on ALL postganglionic cell bodies?
Nicotinic
-this opens ion channels allowing Na+ and Ca2+ to enter the neuron and activate the postganglionic neuron
Most postganglionic neurons release what at a SYMPATHETIC synapse?
Norepinephrine (NE)
-adrenergic neurons
In sympathetic synapses, what is the 1 case without NE/adrenergic
Sweat glands (cholinergic [Ach], muscarinic)
In the sympathetic pathway, adrenergic receptors can be divided into:
alpha (1,2) and beta (1,2,3)
-reminder: exception of sweat glands and first synapse from CNS which use cholinergic receptors