Exam 3 - ANS - Composition Flashcards
The ______ is a system of visceral sensory (afferent) and visceral motor (efferent) neurons that regulates the activity of smooth muscle, cardiac muscle, and many glands
autonomic nervous system
Like the somatic nervous system, the autonomic nervous system operates via
reflex arcs
A continual flow of nerve impulses from ______ in visceral organs and blood vessels propagate into integrating centers in the central nervous system
autonomic sensory neurons
impulses in _______ propagate to various effector tissues (smooth muscle, cardiac muscle, many glands)
autonomic motor neurons
Peripheral nervous system (PNS) consists of all nervous tissue outside the central nervous system: name all three
-SNS, ANS, and ENS
-Each subdivision of the PNS has both sensory and motor neurons. The motor part of the autonomic nervous system consists of two branches:
sympathetic division and parasympathetic division
Look at slide 4 of the PPT
NICE!
Input to the ANS:
Most input to the autonomic nervous system comes from autonomic sensory neurons, which are mostly interoceptors, such as . . .
Chemoreceptors that monitor blood CO2 levels
Mechanoreceptors that detect the degree of stretch in walls of organs (stomach, urinary bladder, intestines, uterus) or blood vessels
monitor blood CO2 levels
Chemoreceptors
detect the degree of stretch in walls of organs (stomach, urinary bladder, intestines, uterus) or blood vessels
Mechanoreceptors
Input to the ANS:
The signals are not consciously perceived most of the time, but intense activation of ____ may produce conscious sensation (such as angina pectoris from inadequate blood flow to the heart)
interoceptors
regulate visceral activities by increasing (exciting) or decreasing (inhibiting) activities in their effector tissues (cardiac muscle, smooth muscle, glands)
Autonomic neurons
Unlike skeletal muscle, tissues innervated by the ANS often have an _____ that enables them to continue to operate even if their nerve supply is damaged (heart beat, gastrointestinal tract contractions)
intrinsic function
ANS motor innervation:
Whereas a single myelinated somatic motor neuron extends from the CNS to the skeletal muscle fibers in its motor unit, autonomic motor pathways consist of …
…two motor neurons in series
image on slide 7 of PDF
ANS motor innervation:
The first neuron has its cell body in the CNS, and its myelinated axon extends from the CNS to….
an autonomic ganglion. This is the pre-ganglionic neuron
image on slide 8 of PDF
ANS motor innervation:
The second neuron has its cell body in the ganglion, and its unmyelinated axon extends from…
…the ganglion to the effector. This is the post-ganglionic neuron
An additional difference between somatic and autonomic motor neurons is that _____ release only acetylcholine (Ach) as their neurotransmitter, but ______ release either acetylcholine or norepinephrine (NE)
somatic motor neurons
autonomic motor neurons
somatic motor neurons release….
… only acetylcholine (Ach) as their neurotransmitter
autonomic motor neurons release….
…either acetylcholine or norepinephrine (NE)
As a general principle, nerve impulses from one division of the ANS stimulate increased activity in an organ (excitation), and impulses from the other division decrease activity (inhibition), for example:
Explain the heart
Explain the GI tract
The heart rate is increased by an increased rate of nerve impulses from sympathetic division, and decreased by an increased rate of nerve impulses from the parasympathetic division
Muscular movements of the GI tract are slowed by sympathetic stimulation, and increased by parasympathetic stimulation
Dual innervation:
An increase of activity in one division of the ANS is generally accompanied by a corresponding decrease of activity in the other division. As the vertical reference line above moves to the left or right, the activity of one division increases and the activity of the other correspondingly decreases
Look at slide 13 of PPT for a visual
is called the “fight-or-flight” division because its actions result in increased alertness and increased metabolic activities
The sympathetic division
is termed the “rest-and-digest” division since its activities conserve and restore body energy and are involved in digestion
The parasympathetic division
Autonomic motor pathways consist of two neurons:
Preganglionic neuron
Postganglionic neuron
The first of the two motor neurons in any autonomic motor pathway
Cell body is in the brain or spinal cord
Axon exits the CNS as part of a cranial nerve or spinal nerve
Conveys nerve impulses from the CNS to autonomic ganglia
Preganglionic neuron
The second of the two motor neurons in any autonomic motor pathway
Cell body and dendrites are in an autonomic ganglion
Relays nerve impulses from autonomic ganglia to visceral effectors
Postganglionic neuron
Preganglionic neurons of the sympathetic division have their cell bodies in the lateral gray horns of the 12 thoracic segments and the first 2 lumbar segments of the spinal cord
Sympathetic division preganglionic motor neurons
Preganglionic neurons of the parasympathetic division have their cell bodies in the nuclei of cranial nerves _______, and in the lateral gray horns of the ________ segments of the spinal cord
III, VII, IX, and X of the brain stem
second through the fourth sacral
are the sites of synapses between sympathetic preganglionic and postganglionic neurons
Sympathetic ganglia
Sympathetic ganglia are of two major types:
Sympathetic trunk ganglia
Prevertebral ganglia
Also called vertebral chain ganglia, or paravertebral ganglia
Ganglia lie in a vertical row on each side of the vertebral column
Preganglionic axons are usually short
Postganglionic axons mostly innervate organs above the diaphragm
Postganglionic axons are generally fairly long
Sympathetic trunk ganglia:
Sympathetic trunk ganglia:
Also called….
vertebral chain ganglia, or paravertebral ganglia
Sympathetic trunk ganglia:
Ganglia lie in a…
vertical row on each side of the vertebral column
Sympathetic trunk ganglia:
______ axons are usually short
Preganglionic
Sympathetic trunk ganglia:
_____ axons mostly innervate organs above the diaphragm
Postganglionic
Sympathetic trunk ganglia:
______ axons are generally fairly long
Postganglionic
Prevertebral ganglia:
The ganglia are ____ to the vertebral column, close to the large abdominal arteries
Postganglionic axons mostly innervate organs below the diaphragm
As with paravertebral ganglia, preganglionic axons are usually short and postganglionic axons are generally fairly long
anterior
Prevertebral ganglia:
_____ axons mostly innervate organs below the diaphragm
As with paravertebral ganglia, preganglionic axons are _____ and postganglionic axons are ____
Postganglionic
usually short
generally fairly long
There are five major prevertebral ganglia:
Celiac ganglion
Superior mesenteric ganglion
Inferior mesenteric ganglion
More worried about first 3
Aorticorenal ganglion
Renal ganglion
Parasympathetic ganglia:
Preganglionic axons of the parasympathetic division synapse with….
Most terminal ganglia are located….
Preganglionic axons are typically ___
Postganglionic axons are…
…postganglionic neurons in terminal ganglia
…close to or within the wall of the visceral organ
long
…short, or seemingly non-existent
Parasympathetic ganglia:
Parasympathetic ganglia of the head have specific names:
Ciliary ganglion
Pterygopalatine ganglion
Submandibular ganglion
Otic ganglion
Parasympathetic splanchnic nerves extend to viscera
Parasympathetic splanchnic nerves extend to
viscera
Axons of parasympathetic neurons extend to parasympathetic postganglionic neurons in terminal ganglia in the walls of the colon, ureters, urinary bladder, and reproductive organs by means of ….
Pelvic splanchnic nerves
Sympathetic trunk ganglia connections:
Sympathetic preganglionic neurons arriving at sympathetic trunk ganglia may connect with postganglionic neurons by….
NAME ALL FOUR EXAMPLES
Synapsing in the ganglion it first reaches,
OR BY…
Ascending or descending before synapsing,
OR BY…
Continuing, without synapsing, through the trunk ganglion to a prevertebral ganglion and synapsing there with postganglionic neurons,
OR BY…
Continuing without synapsing through both the sympathetic trunk ganglion and a prevertebral ganglion to extend to chromaffin cells of the adrenal medullae
Projection patterns: sympathetic branch
This is a ____ projection pattern
Explains in part why sympathetic responses typically affect….
divergent
…almost the entire body, and why they do so simultaneously
Projection patterns: sympathetic branch
Postganglionic axons of the sympathetic division usually terminate in….
everal effectors after leaving their ganglia
Projection patterns: sympathetic branch
Postganglionic axons of the sympathetic division usually terminate in….
Several effectors after leaving their ganglia
Projection patterns: parasympathetic branch
Parasympathetic preganglionic neurons have few _____, and synapse with a limited number of postganglionic neurons, all of which are in the same ____
This is technically a divergent projection pattern (but not much divergence)
Explains in why parasympathetic responses can be localized to a single effector
axon collaterals
visceral effector
Projection patterns: parasympathetic branch
This is technically a divergent projection pattern (but not much divergence)
Explains in why parasympathetic responses can be….
….localized to a single effector
Projection patterns: parasympathetic branch
Parasympathetic postganglionic axons terminate in the…
…same effector after leaving their ganglia (rather than branching out to different effectors)
______ are tangled networks of neurons formed jointly by the sympathetic and parasympathetic nervous systems
Autonomic plexuses
They are present in the thorax, abdomen, and pelvis
Many of them lie along major arteries
Autonomic plexuses
Although autonomic plexuses are generally a component of autonomic motor pathways, they may also contain….
sympathetic ganglia and axons of autonomic sensory neurons
Visceral afferent fibers are commonly also present in
autonomic plexuses
Autonomic plexuses:
There are a number of plexuses in the body, the major ones being:
THORAX
ABDOMEN
PELVIS
Thorax:
Cardiac plexus
Pulmonary plexus
Abdomen:
Celiac plexus
Superior mesenteric plexus
Inferior mesenteric plexus
Pelvis:
Hypogastric plexus
Renal plexus
Major autonomic plexuses in the body
Thorax:
Cardiac plexus
Pulmonary plexus
Major autonomic plexuses in the body
Abdomen:
Celiac plexus
Superior mesenteric plexus
Inferior mesenteric plexus
Major autonomic plexuses in the body
Pelvis:
Hypogastric plexus
Renal plexus
at the base of the heart, it surrounds the large blood vessels emerging from the heart. It is contributed to by both post-ganglionic sympathetic and pre-ganglionic parasympathetic nerves. Sympathetic neurons to this plexus increase heart rate and contractility. Parasympathetic innervation, provided by the vagus nerve, supplies fibers to the heart that slow heart rate.
Cardiac plexus:
posterior to each lung, sympathetic and parasympathetic branches of the autonomic nervous system serve the lungs, bronchi, and pulmonary blood vessels.
Sympathetic innervation causes bronchodilation.
Parasympathetic pathway causes bronchoconstriction and increased secretion from mucous glands of the bronchial tree
Pulmonary plexus:
It is contributed to by both post-ganglionic sympathetic and pre-ganglionic parasympathetic nerves. Sympathetic neurons to this plexus increase heart rate and contractility. Parasympathetic innervation, provided by the vagus nerve, supplies fibers to the heart that slow heart rate.
Cardiac plexus:
Pulmonary plexus:
Sympathetic innervation causes…
Parasympathetic pathway causes…
…bronchodilation.
…bronchoconstriction and increased secretion from mucous glands of the bronchial tree
Celiac plexus (AKA solar plexus): the largest autonomic plexus, it surrounds the celiac and superior mesenteric arteries, and is at the level of the last thoracic / first lumbar vertebrae.
Superior mesenteric plexus: supplies the small and large intestine
Inferior mesenteric plexus: innervates the large intestine
Abdominal plexuses
Abdominal plexuses all three?
Celiac plexus (AKA solar plexus): the largest autonomic plexus, it surrounds the celiac and superior mesenteric arteries, and is at the level of the last thoracic / first lumbar vertebrae.
Superior mesenteric plexus: supplies the small and large intestine
Inferior mesenteric plexus: innervates the large intestine
Hypogastric plexus: supplies pelvic viscera, which comprises the urinary bladder and genital organs
Renal plexus: located near the kidneys (as the name implies), supplies renal arteries within the kidneys and the ureters
Pelvic plexuses
Pelvic plexuses
Hypogastric plexus: supplies pelvic viscera, which comprises the urinary bladder and genital organs
Renal plexus: located near the kidneys (as the name implies), supplies renal arteries within the kidneys and the ureters
Cell bodies are part of the lateral horns of all thoracic segments plus the first two or three lumbar segments of the spinal cord
Preganglionic axons leave the spinal cord through the anterior root of a spinal nerve along with somatic motor neurons at the same level, and exit through the intervertebral foramina
The axons are myelinated
Sympathetic Preganglionic Neurons
The myelinated axons pass through a white ramus communicans to enter an adjoining paravertebral (chain) ganglion, thereby forming part of the sympathetic trunk, AKA sympathetic chain
White rami communicantes
White rami communicantes are present only in the thoracic and first two lumbar nerves (T1-L2), since those are the only regions with sympathetic outflow
White rami communicantes
______ are paired, one on each side of the vertebral column, typically consisting of:
3 cervical ganglia 11 or 12 thoracic ganglia 4 or 5 lumbar ganglia 4 or 5 sacral ganglia 1 coccygeal ganglion (fused at midline)
Sympathetic trunk ganglia
Sympathetic trunk ganglia are paired, one on each side of the vertebral column, typically consisting of:
3 cervical ganglia 11 or 12 thoracic ganglia 4 or 5 lumbar ganglia 4 or 5 sacral ganglia 1 coccygeal ganglion (fused at midline)
Cervical ganglia:
Sympathetic preganglionic fibers that serve the head and neck emerge from spinal cord segments T1 – T6, and ascend to synapse with postganglionic neurons within cervical ganglia in the neck, comprising:
Superior cervical ganglion
Middle cervical ganglion
Inferior cervical ganglion
Cervical ganglia:
Superior cervical ganglion postganglionic sympathetic fibers supply the head and heart
Sweat glands Smooth muscle of the eye Blood vessels of the face Salivary glands Pineal gland Lacrimal glands Heart
Cervical ganglia:
Middle cervical ganglion and inferior cervical ganglion postganglionic sympathetic fibers supply the ____
heart
Which cervical ganglia supply the heart
middle and inferior cervical ganglion
The thoracic region receives most of the….
sympathetic preganglionic axons
Postganglionic fibers from the thoracic sympathetic trunk innervate . . .
Heart Lungs Bronchi Sweat glands Blood vessels of the skin Arrectores pilorum muscles
Sympathetic trunk pathways
Axons leave the sympathetic trunk in four possible ways:
Enter spinal nerves
Form cephalic periarterial nerves
Form sympathetic nerves
Form splanchnic nerves
What are the four ways that axons leave the sympathetic trunk?
Enter spinal nerves
Form cephalic periarterial nerves
Form sympathetic nerves
Form splanchnic nerves
Sympathetic trunk pathways: enter a spinal nerve
Some incoming sympathetic preganglionic neurons synapse with postganglionic neurons either in the ganglion at the level of entry, or farther up or down the sympathetic chain
True
Sympathetic trunk pathways: enter a spinal nerve
Axons of those postganglionic neurons leave the trunk by means of a…
and then merge with?
…gray ramus (gray ramus communicans)
then merge with the anterior ramus of a spinal nerve
what is the gray ramus communicans?
AKA the gray ramus, in which the sympathetic trunk pathway of a spinal nerve has axons of postganglonic neurons that leave the trunk via the gray ramus and then merge with the anterior ramus of a spinal nerve
Sympathetic chains:
Axon collaterals from preganglionic neurons may pass up or down the sympathetic trunk for a variable distance, forming….
…sympathetic chains, which are the fibers on which the ganglia are located
Gray rami communicantes:
Unmyelinated postganglionic axons pass through a gray ramus communicans to connect the….
….ganglia of the sympathetic trunk to spinal nerves
Rami communicantes:
Since gray rami communicantes are associated with all spinal nerves, they outnumber white rami communicantes, which are associated with…
…only the thoracic nerves and two or three lumbar nerves
Sympathetic trunk pathways: cephalic periarterial nerves
Some preganglionic neurons ascend in the sympathetic trunk to the _____, where they synapse with postganglionic neurons
superior cervical ganglion
Sympathetic trunk pathways: cephalic periarterial nerves
Those postganglionic neurons extend to the head by wrapping around and following certain arteries (such as the carotid artery) from the neck to the head, forming….
cephalic periarterial nerves
cephalic periarterial nerves
postganglionic neurons extend to the head by wrapping around and following certain arteries (such as the carotid artery) from the neck to the head
Sympathetic trunk pathways: cephalic periarterial nerves
Cephalic periarterial nerves supply sympathetic innervation to
- skin of the face (sweat glands, smooth muscle of blood vessels, arrectores pilorum muscles)
- visceral effectors of the head (smooth muscles of the eye, lacrimal glands, pineal gland, nasal mucosa, salivary glands)
Sympathetic trunk pathways: sympathetic nerves
After synapsing with preganglionic neurons, some postganglionic neurons form sympathetic nerves that extend to visceral effectors in the thoracic cavity, providing:
Sympathetic nerves to the heart (the superior, middle, and inferior cervical ganglia, and first through fourth thoracic ganglia)
Sympathetic nerves to smooth muscle of bronchi and lungs
Some sympathetic preganglionic neurons pass through the trunk without terminating in it. They then form nerves called
splanchnic nerves (SPLANK-nik) that generally extend to prevertebral ganglia
what do splanchnic nerves typically extend to?
prevertebral ganglia
Splanchnic(pertaining to the viscera) nerves are formed by ______ that pass through the sympathetic trunk without terminating in it, then terminate in prevertebral ganglia
preganglionic axons
Postganglionic neurons of the greater splanchnic nerve supply . . .
Liver Stomach Spleen Small intestine Kidney
Postganglionic neurons of the lesser splanchnic nerve innervate . . .
Small intestine
Colon
Postganglionic neurons of the lumbar splanchnic nerve innervate . . .
Colon
Rectum
Genitals
Urinary bladder
Adrenal medulla
Although there are no postganglionic neurons from the adrenal medullae, developmentally the adrenal medullae are derived from the same type of precursor cell (chromaffin cell) that gives rise to postganglionic neurons elsewhere in the body.
Anymore brain busters?
Adrenal medulla
the adrenal medullae themselves comprise a large complex of ______, the cells of which release hormones into the blood (mostly epinephrine, some norepinephrine, a trace of dopamine)
postganglionic neurons
_____ extend to the adrenal medullae
Sympathetic preganglionic neurons
Parasympathetic Preganglionic Neurons
Cell bodies are in nuclei in the ______ of the second through fourth sacral segments of the spinal cord
brain stem and in the lateral horns
Parasympathetic Preganglionic Neurons
Axons emerge as part of a cranial nerve, or as part of the anterior root of a spinal nerve:
The ______ consists of preganglionic axons from the brain stem in four of the cranial nerves
The ______ comprises preganglionic axons in anterior roots of the second through fourth sacral spinal nerves
The axons are myelinated, and end in terminal ganglia close to the organ they innervate
cranial parasympathetic outflow
sacral parasympathetic outflow
Cranial parasympathetic ganglia
Paired (left and right), and located close to the organs they innervate:
Ciliary ganglia located near the posterior aspect of each eyeball; preganglionic axons from oculomotor nerves (CN III); postganglionic axons innervate smooth muscles in eyeball
Pterygopalatine ganglia (ter-i-gō-PAL-a-tin); preganglionic axons from facial (VII) nerves; postganglionic axons to nasal mucosa, pharynx, and to lacrimal glands
Cranial parasympathetic ganglia
Paired (left and right), and located close to the organs they innervate:
______ located near the posterior aspect of each eyeball; preganglionic axons from oculomotor nerves (CN III); postganglionic axons innervate smooth muscles in eyeball
_______ (ter-i-gō-PAL-a-tin); preganglionic axons from facial (VII) nerves; postganglionic axons to nasal mucosa, pharynx, and to lacrimal glands
Ciliary ganglia
Pterygopalatine ganglia
Cranial parasympathetic ganglia:
_____ located near submandibular salivary gland ducts; preganglionic axons from facial (VII) nerves; postganglionic axons to submandibular salivary glands and sublingual salivary glands
Otic ganglia inferior to each foramen ovale; pregangliionic axons from glossopharyngeal (IX) nerves; postganglionic axons to parotid salivary glands
Submandibular ganglia
Cranial parasympathetic ganglia:
_____ inferior to each foramen ovale; pregangliionic axons from glossopharyngeal (IX) nerves; postganglionic axons to parotid salivary glands
Otic ganglia
Cranial parasympathetic ganglia
List four examples:
Ciliary ganglia
Pterygopalatine ganglia
Submandibular ganglia
Otic ganglia
Vagal outflow
Most (80%) of the total craniosacral outflow is carried by preganglionic axons that leave the brain as part of the vagus nerves (cranial nerve X)
The vagus nerve sends axons to the . . .
Heart Airways of the lungs Liver Gallbladder Stomach Pancreas Small intestine Large intestine
Parasympathetic splanchnic nerves
Preganglionic neurons of the sacral parasympathetic outflow form pelvic splanchnic nerves, the postganglionic neurons of which innervate smooth muscle and glands in . . .
Colon
Ureters
Reproductive organs
Urinary bladder
Parasympathetic splanchnic nerves
Preganglionic neurons of the sacral parasympathetic outflow form ______, the postganglionic neurons of which innervate smooth muscle and glands in . . .
pelvic splanchnic nerves
sympathetic trunk ganglia AKA
vertebral chain ganglia
paravertebral ganglia
