Flashcards in Autonomic Nervous System Deck (36)
What are the roles of the parasympathetic system?
Enhances energy storage; decreases cardiac output, blood pressure, increase gut peristalsis, salivation, pupillary constriction and bladder contraction.
What are the roles of the sympathetic nervous system?
Energy needs to be expended; increase heart rate, decreases peristalsis, blood from gut to muscles, adrenal gland can dump epinephrine into circulation so widespread, long-lasting effects possible.
What does the autonomic system control?
-Controls visceral activity
-You have no conscious awareness of heartbeat, breathing, digestion, sweat, diversion of blood to active muscles
What are the 3 main divisions of the autonomic system?
3) Enteric nervous system
What are the similarities between the somatic and autonomic nervous systems?
-Visceral sensory fibers
-Descending pathways control motor neurons
What is the one major difference between the somatic and autonomic systems?
-Sympathetic & parasympathetic efferents do not reach their targets directly: a two-neuron chain is involved
1) Preganglionic cell body in CNS, 2) postganglionic neuron in ganglion
Where are sympathetic ganglia located?
Where are parasympathetic ganglia located?
near innervated organ
True or false: Sympathetic and parasympathetic preganglionic fibers have thin myelin.
True or false: Sympathetic and parasympathetic postganglionic fibers are myelinated.
Where is the neurotransmitter Ach (Acetylcholine) used?
In parasympathetic and in the 1st synapse in the sympathetic. Although they have different Ach receptors.
Where is the neurotransmitter NE (norepinephrine) used?
In the 2nd sympathetic synapse.
Where are the sympathetic preganglionic fibers?
from T1 to L2/3 segments
What is the path of the sympathetic preganglionic fibers?
travel in spinal nerve ---> sympathetic change ---> prevertebral ganglia ---> adrenal gland
Where are parasympathetic preganglionic neurons located?
in the brainstem & sacral cord
How do parasympathetic nerves travel?
in cranial & sacral nerves
Where does the parasympathetic system outflow to?
thoracic, abdominal and pelvic viscera, none to limbs
What are the components in cranial parasympathetics?
- III, pupil sphincter and ciliary muscle, accomodation reflex
- VII, pterygopalatine ganglion
- IX, otic ganglion
- X, to heart, lungs, lower esophagus, stomach, ascending and transverse colon, pancreas
What are key points on the path of CN III Oculomotor?
- Edinger-Westphal nucleus, located in midbrain
-It controls pupillary constrictor muscle fibers, which decrease pupil diameter (pupillary reflex)
-It controls the ciliary muscle, which accommodates lens for near vision
What are key points on the path of CN VII Facial?
-Superior salivatory nucleus in tegmentum of pons, made up of parasympathetic preganglionic cell bodies
-Axons exit along with other facial nerve fibers, they terminate in 1) the pterygopalatine ganglion and lacrimal gland; and 2) the submandibular ganglion and sublingual salivary glands
What are key points in the path of CN XI Glossopharyngeal?
-Inferior salivatory nucleus in the medulla, parasympathetic preganglionic cell bodies of glossopharyngeal nerve are there.
-Axons exit along with other glossopharyngeal nerve fibers and terminate in the otic ganglion and parotid salivary gland
What are key points in the path of CN X Vagus?
- Dorsal motor nucleus has Parasympathetic preganglionic cell bodies serving GI tract and gut derivatives, and Nucleus ambiguus which has Parasympathetic preganglionic cell bodies serving heart. Both of these are in medulla.
-Axons exit along with other vagal nerve fibers, they terminate in the wall of target tissue (viscera from thorax to transverse colon)
What are key points in the path of Sacral Parasympathetic Outflow?
- Sacral cord, S2-4 level, region of lateral horn, location of preganglionic parasympathetic cell bodies
- Axons exit within ventral root and course within splanchnic nerves
- They terminate in wall of target tissue (Viscera from transverse colon to rectum
Includes bladder, uterus, etc.)
Location of postganglionic nerve cell bodies
Select the correct matching pair.
A) Superior salivatory nucleus: IX
B) Edinger-Westphal: IV
C) Nucleus ambiguus: X
D) Inferior salivatory nucleus: VI
E) Selena Gomez: Justin Bieber
C) Nucleus ambiguus: X
Where is the source of sympathetic preganglionic fibers?
Spinal cord levels T-1 to L-2/3
After preganglionic sympathetic fibers leave ventral root they do 1 of 4 things ...
1) Some fibers synapse in nearest ganglion
2) Some ascend chain, synapse in SCG or MCG
3) Some descend, synapse in lumbar/ sacral ganglia
4) Some traverse chain, emerge as splanchnic nerves
Preganglionic sympathetic fibers leave the cord at thoracic and upper lumbar levels using ventral roots then ...
They travel to the sympathetic chain on white communicating rami (white because the preganglionic fibers are myelinated) some end in the sympathetic chain at that level they exited from while others proceed to another level.
Postganglionic sympathetic fibers rejoin the spinal nerve via ...
gray communicating rami (so named because they are unmyelinated).
True or false: Only T1 to L2/3 spinal nerve have white communicating rami while gray communicating rami (and postganglionic sympathetic fibers) are present on all spinal nerves.