Intro to Autonomics Flashcards
The peripheral nervous system is divided into ______ and ______ division
Sensory (afferent)
Motor (efferent)
The PNS is functionally divided into sensory and motor divisions. The sensory inputs and motor outputs are subdivided into what 2 categories?
Somatic vs. Visceral
General vs. Special
What serves as the general visceral motor + sensory division of the peripheral nervous system, supplying motor neuron innervation to smooth muscle, cardiac muscle, and glands as well as monitoring sensations within visceral organs?
The autonomic nervous system and visceral sensory neurons
Regulates visceral functions like heart rate, BP, digestion, and urination
The autonomic nervous system monitors what types of sensations in the visceral organs?
Stretch
Temperature
Chemical changes
Irritation
[note that no pain results when visceral organs are cut - pain results from chemical irritation or inflammation]
Visceral pain is often perceived to be of somatic origin. What is this concept called?
Referred pain
The autonomic nervous system consists of a 2-neuron system extending from the CNS to the organs. What is this 2-neuron system?
Pre-synaptic neurons in the CNS
Post-synaptic neurons in the periphery
Which branch of the ANS is considered catabolic? Why?
Sympathetic
Expends energy, prepares for fight-or-flight
The sympathetic nervous system is distributed to all ______ portions of the body; it is responsible for _________ of vessels except for coronary arteries
Vascularized
Vascoconstriction
Which branch of the ANS is considered anabolic? Why?
Parasympathetic
Promotes normal function - conserves energy; rest and digest
The parasympathetic nervous system is restricted to what body areas?
Head, neck, body cavities + genitalia
NOT found in body wall or limbs
All glandular secretion is due to the ______ nervous system with the exception of sweat glands
Parasympathetic
[note that sweat glands are controlled by sympathetic system]
What effect does the sympathetic system have on the eyes?
Dilates pupils
What effect does the sympathetic system have on the skin? (Specifically arrector pili mm., peripheral blood vessels, sweat glands)
Causes hairs to stand on end - goosebumps
Vasoconstricts
Promotes sweating
What effect does the sympathetic system have on lacrimal and salivary glands?
Slightly decreases lacrimation
Secretion of saliva decreases, becomes thicker/more viscous
What effect does the sympathetic system have on the heart?
Increases heart rate and strength of contraction; inhibits effect of parasympathetic system on coronary vessels, allowing them to dilate
What effect does the sympathetic system have on the lungs?
Inhibits effect of parasympathetic system, resulting in bronchodilation and reduced secretion, allowing for max air exchange
What effect does the sympathetic system have on digestive tract?
Inhibits peristalsis and constricts blood vessels to gut so that blood is available to skeletal muscle; contracts internal anal sphincter to aid fecal incontinence
What effect does the sympathetic system have on the liver and gallbladder?
Promotes breakdown of glycogen to glucose for energy
What effect does the sympathetic system have on the urinary tract?
Vasoconstriction of renal vessels slows urine formation; internal sphincter of bladder contracted to maintain urinary continence
What effect does the sympathetic system have on the male genital system?
Causes ejaculation and vasoconstriction resulting in remission of erection
What effect does the sympathetic system have on the suprarenal medulla?
Release of adrenaline into blood
What effect does the parasympathetic system have on the eyes?
Constricts pupil
Contracts ciliary muscle - allowing lens to thicken for near vision
What effect does the parasympathetic system have on the skin?
NO effect! Does not reach
What effect does the parasympathetic system have on the lacrimal and salivary glands?
Promotes secretion from both
What effect does the parasympathetic system have on the heart?
Decreases rate and strength of contraction (conserving energy); constricts coronary vessels in relation to reduced demand
What effect does the parasympathetic system have on the lungs?
Constricts bronchi and promotes bronchial secretion
What effect does the parasympathetic system have on the digestive tract?
Stimulates peristalsis and secretion
Contracts rectum, inhibits internal anal sphincter to cause defecation
What effect does the parasympathetic system have on the liver and gallbladder?
Promotes building/conservation of glycogen; increaes secretion of bile
What effect does the parasympathetic system have on the urinary tract?
Inhibits contraction of internal sphincter of bladder, contracts detrusor muscle of bladder causing urination
What effect does the parasympathetic system have on the genital system?
Produces engorgement (erection) of erectile tissues of the external genitals
What effect does the parasympathetic system have on the suprarenal medulla?
No effect! Does not innervate
Compare the sympathetic vs. parasympathetic nervous systems in terms of length of their post-synaptic fibers
Sympathetic: long postsynaptic fibers
Parasympathetic: short postsynaptic fibers
Compare the sympathetic vs. parasympathetic nervous systems in terms of branching of fibers
Sympathetic: highly branched, influence many organs at once
Parasympathetic: few branches; localized effects
Compare the sympathetic vs. parasympathetic nervous systems in terms of neurotransmitter released by POST-synaptic axons
Sympathetic: mostly norepinephrine (adrenergic)
Parasympathetic: acetylcholine (cholinergic)
The basic organization of the sympathetic division of the ANS:
Presynaptic neurons are found in the _______ _______horn of the spinal cord and exit from spinal nerves ____ to ____
They are linked by short nerves into ________ ________ that contain postsynaptic neurons
Lateral (intermediolateral) gray; T1 - L2/3
Sympathetic trunks
Sympathetic trunk ganglia are also called what?
Paravertebral or chain ganglia, they are found on both sides of the vertebral column
The sympathetic division of the ANS supplies _____ organs in the internal body cavities and structures of _______ body regions
Visceral; superficial
Presynaptic sympathetic neurons are arranged in interomediolateral cell columns along T1-L2/3 of the spinal cord, supplying corresponding body areas. This is known as the ________ arrangement of presynaptic sympathetic neurons
Somatotopic
The pre and post synaptic fibers of the sympathetic system communicate at the sympathetic trunks in the thoracic region via _____ and _____ _________
White (pre); gray (post) communicans
Sympathetic presynaptic neurons in the _____ horn of the spinal cord send myelinated axons through the adjacent _____ root into spinal nerves
______ _____ ________ carry these axons from the spinal nerve to the associated sympathetic trunk ganglia where they synapse
______ ______ _______ carry post-synaptic sympathetic fibers back to the spinal nerve to travel to peripheral structures
Lateral; ventral
White rami communicans
Gray rami communicans
T/F: sympathetic axons may ascend or descend in the sympathetic trunk to synapse in another ganglion
True
In the sympathetic pathway via prevertebral (collateral) ganglia, axons pass through the sympathetic trunk and exit on _______ ______ nerves.
This is only found where??
Thoracic splanchnic
Found only in abdomen and pelvis; lies anterior to vertebral column
In the sympathetic pathway via prevertebral (collateral) ganglia, axons pass through the sympathetic trunk and exit on thoracic splanchnic nerves. This is found only in the abdomen and pelvis and lies anterior to the vertebral column.
The axons synapse in prevertebral (collateral) ganglia on what structures? What effect does this have?
Abdominal aorta
Celiac ganglia
Superior and inferior mesenteric ganglia
Inhibits activity of muscles and glands in visceral organs
What is the role of the adrenal medulla in the sympathetic division of the ANS?
It is a major organ of the sympathetic nervous system
Preganglionic fibers synapse on medullary chromaffin cells, which release great quantities of epinephrine (adrenaline) and norepinephrine when stimulated
NOTE that this is an exception to the 2-neuron pathway for the ANS
How does the parasympathetic division of the ANS represent cranial outflow?
Presynaptic neurons located in brainstem exit via cranial nerves and innervate organs of the head, neck, thorax, and abdomen
Describe the sacral outflow of the parasympathetic division of the ANS
Sacral nerves emerge from S2 to S4
Supplies and innervates organs of pelvis and lower abdomen
Sacral outflow of the parasympathetic division of the ANS consists of presynaptic cell bodies located in the ____ _____ region of spinal ___ matter.
Axons run in _____ roots out via _____ rami. These form ____ _____ nerves.
Sacral outflow is distributed through the ______ ______ plexus
Visceral motor; gray
Ventral; ventral; pelvic splanchnic
Inferior hypogastric
What nervous system consists of neurons in the wall of the GI tract from the esophagus to the anus?
Enteric nervous system
Capable of autonomous functions such as coordination of GI reflexes
Enteric neurons also include postsynaptic neurons for what 2 major nerves?
Cranial nerve X - vagus
Pelvic splanchnic nerves
The sympathetic nervous system uses acetylcholine at presynaptic synapses and norepinephrine at postsynaptic synapses.
What is the exception?
Post-synaptic synapses in sweat glands are cholinergic
The presynaptic neurons are located in the brainstem and sacral spinal cord.
What makes up the cranial part?
What makes up the sacral part?
Cranial part = CN III, VII, IX, X
Sacral part = interomediolateral cell column in S2-4 of spinal cord
A non-selective muscarinic receptor blocker is given to a patient. Which organ will most likely be unaffected?
A. Sweat glands
B. Adrenal glands
C. Heart
D. Vasculature
B. Adrenal glands
[these have no ganglion, nicotinic receptors receive ACh]
Which pharmacologic agent would treat the chief complaint of diarrhea?
A. Muscarinic receptor agonist
B. Nicotinic receptor antagonist
C. Adrenergic receptor agonist
C. Adrenergic receptor agonist
[decreases peristalsis in GI tract, favors constipation]
Describe spinal distribution of sympathetic vs. parasympathetic nervous system
Parasympathetic has sacral and cervical divisions
Sympathetics are located in thoracolumbar area
Which one has the long preganglionic nerve - sympathetic fibers or parasympathetic fibers?
Parasympathetic ANS
