Anatomy - The Autonomic System Flashcards
1
Q
What would happen to a body if we removed all consciousness?
A
All physiological processes would continue virtually unchanged because of the ANS (consciousness only represents a tiny fraction of the activities of the NS)
2
Q
10 functions of ANS?
A
- Regulates body temp2. Coordinates CV function3. Coordinates respiratory function4. Coordinates digestive function5. Coordinates excretory function6. Coordinates reproductive function7. Adjusts internal water8. Adjusts fluid electrolytes9. Adjusts nutrients in tissue fluids10. Adjusts dissolved gas concentrations in bodily fluids
3
Q
Other name for ANS?
A
Visceral motor NS
4
Q
Which special sense is considered a visceral sensory?
A
Taste
5
Q
What 5 general senses are part of the visceral sensory division of the NS?
A
- Stretch2. Pain3. Temperature4. Chemical changes5. Irritation of viscera
6
Q
What 3 tissues does the ANS innervate?
A
- Smooth muscle2. Cardiac muscle3. Glands
7
Q
What are the 2 main differences between the somatic efferent pathway and the autonomic pathway?
A
- LMNs of the SNS synapse directly onto skeletal muscle allowing for precise innervation vs autonomic pathways involve 2 neurons (CNS + PNS) and is diffuse with divergent targeting and indirect control2. LMNs are heavily myelinated therefore have faster conduction vs ANS preganglionic neurons are slightly myelinated and postganglionic ones are not at all, therefore have slower conduction
8
Q
Is ANS conduction faster in the preganglionic or postganglionic nerve?
A
Preganglionic because slightly myelinated
9
Q
Where are the autonomic preganglionic neuron bodies found? 2 names
A
Intermediolateral cell column of spinal cord = lateral horns
10
Q
Parasympathetic NS: how does the length of the preganglionic neuron compare to the postganglionic neuron? Why?
A
Longer preganglionic neuron because intramural ganglia are in the walls of the target organs
11
Q
Sympathetic NS: how does the length of the preganglionic neuron compare to the postganglionic neuron? Why?
A
Longer postganglionic neuron because paravertebral and prevertebral ganglia are close to spinal cord
12
Q
What are the 3 autonomic ganglia of the PNS?
A
- Paravertebral (chain) ganglia2. Prevertebral ganglia 3. Intramural ganglia
13
Q
Describe the organization of the spinal nerves.
A
Rootlets => dorsal/ventral roots => spinal nerves => dorsal/ventral rami
14
Q
Describe the 2 sympathetic autonomic motor innervation pathways to viscera. What does each innervate?
A
- Cardiopulmonary nerves/splanchnics (thoracic cavity): preganglionic neuron in lateral ventral horn of spinal cord => anterior root => spinal nerve => white ramus communicans => synapse in paired paravertebral ganglia (same level/up/down the spinal cord) => postganglionic neuron (cardiopulmonary nerves) => viscera 2. Splanchnics (abdominopelvic cavity): preganglionic neuron in lateral ventral horn spinal cord => anterior root => spinal nerve => white ramus communicans => paired paravertebral ganglia (no synapse and same level/up/down the spinal cord) => splanchnic nerve exiting the paravertebral ganglion => synapse in unpaired prevertebral ganglion => postganglionic neuron => viscera
15
Q
Are there more white or gray rami? Why?
A
Gray because you only need a white rami at the T1-L2 segment of the spinal cord but gray rami occur anywhere along the spinal cord
16
Q
Describe the innervation pathway of the dilation of the pupil and relaxation of the ciliary muscle.
A
Hypothalamus => neurons to thoracic spinal cord => synapse on preganglionic neuron in lateral ventral horn of spinal cord => anterior root => spinal nerve => white ramus communicans => paravertebral ganglion => inferior cervical ganglion => synapse in superior cervical ganglion (paravertebral ganglion up the spinal cord) => postganglionic neuron => gray rami communicans => spinal nerve => anterior ramus => cephalic arterial branch of postganglionic neuron => carotid artery with periarterial plexus => dilator muscles and ciliary body
17
Q
Are both pre and postganglionic nerves true splanchnic?
A
Only preganglionic
18
Q
Are cardiopulmonary splanchnic nerves true splanchnics?
A
NOPE
19
Q
Do sacral splanchnic preganglionic neurons come out of the sacral spinal cord?
A
NOPE, the thoracolumbar one and then travel down the paravertebral chain ganglion to the sacral spinal cord
20
Q
What do we call the sacral parasympathetic preganglionic neurons?
A
Pelvic splanchnics
21
Q
What are the only parasympathetic splanchnics?
A
Pelvic splanchnics
22
Q
Describe the parasympathetic autonomic motor innervation pathway to the hindgut and pelvis.
A
Preganglionic neuron in ventral horn of sacral spinal cord (S2-S4) => anterior root => spinal nerve => pelvic splanchnics => unpaired prevertebral ganglion (no synapse) => synapse in intramural ganglion => postganglionic neuron => viscera
23
Q
Describe the parasympathetic autonomic motor innervation pathway to the foregut and midgut.
A
Vagus nerve => synapse in intramural ganglion => postganglionic neuron => viscera
24
Q
How many neurons from spinal cord involved in visceral motor innervation? What is the exception?
A
2: preganglionic and postganglionic neurons which synapse at ganglia Exception: adrenal medulla composed of modified postganglionic neurons and innervated by preganglionic thoracic splanchnic sympathetic neurons
25
What are the 4 types of splanchnics and what do they each innervate? What kind of innervation does each provide?
1. Thoracic (sympathetic): foregut and midgut of abdomen, adrenal glands, kidneys2. Lumbar (sympathetic): hindgut of abdomen, pelvis3. Sacral (sympathetic): pelvis4. Pelvic (parasympathetic): pelvis and hindgut
26
What do the posterior rami supply?
Back intrinsic muscles and skin covering them
27
What do the anterior rami supply?
Limbs and ventral portion of the body
28
What are 3 other names for the sympathetic chain ganglia?
1. Paravertebral ganglia2. Paravertebral trunks3. Sympathetic ganglia
29
Other name for preganglionic neurons?
First-order neurons
30
Where do the parasympathetic preganglionic neurons synapse along the spinal cord? What do we call this?
1. Cranial nerve nuclei (III, VII, IX, X)2. S2 to S4 spinal segments (sacral spinal cord)Craniosacral outflow
31
Do sacral splanchnic preganglionic neurons come out of the sacral spinal cord?
NOPE, the thoracolumbar one and then travel down the paravertebral chain ganglion to the sacral spinal cord
32
Where do the sympathetic preganglionic neurons synapse along the spinal cord? What do we call this?
T1 to L2 spinal segments = thoracolumbar outflow
33
Sympathetic pathway to the periphery?
Preganglionic neuron in lateral ventral horn of spinal cord => anterior root => spinal nerve => white ramus communicans => synapse paravertebreal ganglion (up/down or same level of spinal cord) => postganglionic neuron in grey ramus communicans => spinal nerve => anterior or posterior ramus
34
What is sudomotion?
Actions of sympathetic nerves that stimulate the sweat glands to activity
35
What is meant by divergence of the sympathetic NS?
4 possible courses taken by presynaptic fibers within the sympathetic trunks:1. Ascend and then synapse2. Synapse at level of entry3. Descend and then synapse4. Pass through sympathetic trunk without synapsing to enter abdominopelvic splanchnic nerves
36
How will the regions that can't be innervated by the vagus nerve be parasympathetically innervated? What are these 2 regions?
Parasympathetic splanchnic nerves in the sacral spinal cord (S2-S4)Hindgut and pelvis
37
Where does vagus nerve innervation start and end?
Starts at foregut and ends after midgut at the left colic flexure (aka where transverse colon becomes the descending colon)
38
What is the parasympathetic NS concerned with?
Preserving energy
39
Describe the parasympathetic NT pathway.
Preganglionic neuron releases ACh => postganglionic nicotinic receptors leading to ACh release => target structure muscarinic receptors => inhibition or excitation of target structure
40
How can parasympathetic innervation on a target structure lead to either inhibition or activation? Example?
Muscarinic receptors can have different effects depending on locationExample: - Heart is inhibited via hyperpolarization leading to bradycardia- Digestive tract smooth muscle is excited by depolarization leading to contractions
41
Describe the sympathetic NT pathway.
Preganglionic neuron releases ACh => postganglionic nicotinic receptors leading to NE release => target strcuture adrenergic receptors
42
Does the parasympathetic NS innervate the skin?
NOPE
43
Why are the white rami communicans white?
Because preganglionic MYELINATED fibers go through them
44
Why are the grey rami communicans grey?
Because postganglionic UNMYELINATED fibers go through them
45
Can the effect of the ACh release by sympa and parasympa preganglionic neurons be either excitatory or inhibitory?
NOPE, always excitatory
46
Describe the pathway of the innervation of the adrenal medulla.
Preganglionic neuron in lateral ventral horn T5 to T9 spinal cord => anterior root => spinal nerve => white ramus communicans => paravertebral ganglion (no synapse) => greater thoracic splanchnic nerve exits => unpaired prevertebral ganglion (no synapse) => synapse on adrenal medulla => release of NE and EPI
47
Other name for prevertebral ganglion?
Collateral ganglion
48
Differences between paravertebral and prevertebral ganglia?
Paravertebral are right next to spinal cord and paired Prevertebral are further from spinal cord and unpaired
49
What are the 7 major effects produced by sympathetic post-ganglionic fibers that travel in spinal nerves (posterior and anterior rami)?
1. Constriction of cutaneous blood vessels and reduction in circulation to the skin (making it cold) as well as to most other organs in body wall2. Acceleration of blood flow to skeletal muscles3. Stimulation of energy production and use by skeletal muscle tissue4. Release of stored lipids from subcutaneous adipose tissue5. Dilation of the pupils to allow more light int the eyes and focusing of the eyes to view distant objects 6. Stimulation of arrector pili muscles, producing goose bumps7. Stimulation of skin sweat glands
50
What kind of innervation do visceral plexuses receive?
Both sympathetic and parasympathetic
51
What is an example of a visceral plexus?
Plexus on the aorta from splanchnic nerve innervation = prevertebral plexus
52
What are the 4 major effects produced by sympathetic cardiopulmonary nerves/splanchnics entering the thoracic cavity?
1. Accelerating the heart rate and increasing the strength of cardiac contractions 2. Dilating coronary vessels3. Dilating of the respiratory passageways 4. Inhibiting muscles and glands of the esophagus
53
Reaction of the heart when sympathetically stimulated?
Works harder => circulating blood at a higher rate and under increased pressures
54
Reaction of air flow when sympathetically stimulated?
Air flow is more efficient => improved delivery of O2 and elimination of CO2
55
What are the 3 types of thoracic sympathetic splanchnics? From what portion of the spinal cord does each exit from?
1. Greater splanchnics: T5 to T9 2. Lesser splanchnics: T9 to T113. Least splanchnics: T12
56
From what portions of the spinal cord do sympathetic cardiopulmonary nerves/splanchnics exit the paravertebral ganglia?
- Cervical spinal cord -T1 to T6
57
From what portions of the spinal cord do sympathetic autonomic motor neurons to the peripheral parts of the body exit from exit the paravertebral ganglia?
- C1/C2 to C8- T1 to Co
58
From what portions of the spinal cord do sympathetic lumbar splanchnics exit from?
L1 to L2
59
From what portions of the spinal cord do sympathetic sacral splanchnics exit from?
L1 to L2
60
How do the sympathetic splanchnics usually travel after they exit the paravertebral ganglion?
They piggy-back on arteries to travel to target organs
61
What are the 7 major effects produced by sympathetic splanchnics that innervate collateral ganglia?
1. Constricting small arteries and reducing flow of blood to visceral organs2. Decreasing the activity of digestive glands and organs, including the stomach, intestines, pancreas, and gallbladder3. Stimulating the release of glucose from the liver's glycogen reserves4. Stimulating the release of lipids from adipose tissue5. Reducing the rate of urine formation in the kidneys6. Relaxing the smooth muscle in the wall of the urinary bladder7. Controlling some aspects of sexual function (e.g. ejaculation in males)
62
Timing of effect of NE and EPI release?
Order of minutes
63
Timing of effects of sympathetic splanchnics that innervate collateral ganglia?
Quick
64
Timing of effects of sympathetic post-ganglionic fibers that travel in spinal nerves (posterior and anterior rami)?
Quick
65
Timing of effects of sympathetic cardiopulmonary nerves/splanchnics?
Quick
66
3 locations of parasympathetic cranial nuclei?
1. Mesencephalon2. Pons3. Medulla
67
Where are parasympathetic intramural ganglia located?
Within or adjacent to the target organs
68
Which are more divergent: sympathetic or parasympathetic preganglionic neurons? Explain
Sympathetic ones Parasympathetic postganglionic neurons synapsing with one preganglionic neuron usually are all located in the same intramural ganglion and thus influence the same target organs => more specific and localized effect
69
With how many postganglionic neurons does a typical parasympathetic preganglionic neuron synapse with?
6-8
70
Other name for postganglionic neurons?
Second order neurons
71
Is there any parasympathetic output to limbs and skin?
NOPE
72
What are the 9 major effects produced by the parasympathetic division of the ANS?
1. Constriction of the pupils to restrict the amount of light entering eyes, and focusing onnearby objects2. Secretion by digestive glands, including salivary glands, gastric glands, duodenal glands,intestinal glands, pancreas, and liver3. Secretion of hormones that promote nutrient absorption by peripheral cells4. Increased smooth muscle activity along the digestive tract5. Stimulation and coordination of defecation6. Contraction of the urinary bladder during urination7. Constriction of the respiratory passageways8. Reduction in heart rate and force of contraction9. Sexual arousal and stimulation of sexual glands in both sexes
73
Where are visceral sensory fibers usually found? Exception?
Accompany visceral motor fibers and enter spinal cord at similar spinal cord levelsException: heart sensory
74
What sensation do sympathetic sensory fibers carry?
Generally pain
75
Which parasympathetic nerve fibers carry pain sensations?
Cranial nerves IX and X
76
Which ANS neurons participate in visceral reflexes?
Preganglionic neurons in lower brain stem and spinal cord
77
What are the simplest functional units of the ANS?
Visceral reflexes
78
What CNS structure is the one that mainly modifies, facilitates or inhibits visceral reflexes? What other brain structures do this?
HypothalamusOthers:- Brain stem- Spinal cord- Amygdala- Cerebral cortex
79
What are the 9 parasympathetic reflexes?
1. Gastric and intestinal reflexes2. Defecation 3. Urination 4. Light and consensual light reflexes5. Swallowing reflex 6. Vomiting reflex 7. Coughing reflex 8. Cardioinhibitory reflex 9. Sexual arousal
80
What are the 4 sympathetic reflexes?
1. Cardioacceleratory reflex2. Vasomotor reflex3. Pupillary reflex4. Ejaculatory reflex (in males)
81
What is the point and shoot innervation of the penis?
1. Point => parasympathetic => erection2. Shoot => sympathetic => ejaculation
82
Difference in size between sympathetic and parasympathetic ganglia?
Sympa: largeParasympa: invisible to naked eye
83
Which is more complex: sympa or parasympa?
Sympa
84
Which innervates more organs: sympa or parasympa?
Sympa
85
What needs to be removed to be able to see the sympathetic trunk ganglia in a dissection?
Parietal pleura of the lungs
86
What do the sympathetic trunk ganglia attach to?
1. Spinal cord2. Intercostal nerve
87
How many sympathetic trunk ganglia are there?
Approximately one for each spinal nerve, but some fuse, especially in the head (up to 7)
88
How are prevertebral ganglia formed?
Fusion of paravertebral ganglia
89
Where are prevertebral ganglia found?
Abdomen and pelvis, anterior to the vertebral column
90
What do prevertebral ganglia look like?
Thick connective tissue, almost like cartilage
91
What are the 3 major effects produced by sympathetic nerves to the head?
1. Inhibit lacrimal, nasal, and salivary glands (i.e. dry mouth)2. Stimulate eye muscles that dilate iris, and adapt to far vision3. Stimulate eyelid muscles to keep them open
92
How does the pathway of the thoracic cardiopulmonary sympathetic splanchnics vary between the heart and lungs? How did this discovery affect heart transplants?
- Lungs: exit spinal cord at same level as the parasympathetic chain ganglia- Heart: travel to cervical sympathetic ganglion => they used to cut both the old and donor hearts through right atrium and reattach the new heart to a portion of the old RA so that the nerve supply would stay intact, hoping it would regrow around the new heart. However, this does not work (HA!) so now we just transplant the full heart and give it a pacemaker
93
What parts of the body does the parasympathetic cranial output innervate?
1. Head2. Neck3. Thorax4. Foregut/midgut
94
What 5 plexuses does the vagus nerve innervate?
1. Cardiac 2. Pulmonary plexus3. Esophageal plexus4. Celiac plexus5. Superior mesenteric plexus
95
Other name for left colic flexure?
Splenic flexure
96
What does the celiac plexus innervate?
1. Liver2. Gallbladder 3. Stomach4. Spleen 5. Pancreas
97
What plexus do the parasympathetic splanchnic nerves form in the hindgut?
Hypogastric plexus
98
Why is it important the the parasympathetic NS is not as divergent as the sympathetic one?
Responsible for excretion (urination and defecation) AND reproduction and that needs to be discretely innervated
99
Other word for erection?
Erectile tumescence
100
What does the brain do once it receives visceral sensory information?
It interprets it as hunger, fullness, pain, nausea, or well-being
101
Are visceral sensations easy to localize with precision?
NOPE
102
Does a patient experience pain when his visceral organs are cut or scraped?
NOPE
103
Are somatic sensations easy to localize with precision?
YUP
104
What is a sharp pain?
Somatic pain relating to the parietal wall (because it has somatic sensory receptors)
105
What is a dull pain?
Visceral pain
106
What is referred pain? What is it due to?
Visceral pain perceived as originating from the skin or outer body (as somatic pain)May be due to reflexive vasoconstriction in the vessels supplying the corresponding somatic segments
107
Why does the referred pain of the heart extends to the medial arm?
Because intercostal nerve T2 which becomes the brachial nerve exits the spinal cord at the same level as the visceral afferents from the heart
108
Describe the pathway of a visceral reflex arc.
Sensory receptor in viscera => visceral sensory fiber => dorsal root ganglion => dorsal root => dorsal horn of spinal cord => synapse with preganglionic neuron at integration center of the spinal cord => preganglionic neuron exits spinal cord and synapses at one of the autonomic ganglia => postganglionic neuron synapse on organ
109
Do visceral reflexes have the same basic components as somatic reflexes?
Yes, but all visceral reflexes are polysynaptic (involve an interneuron)
110
What is the enteric NS?
Complete 3 neuron reflex arc that exist entirely within the wall of the digestive tube
111
Do both urination and defecation require voluntary relaxation of sphincters?
YUP
112
Stimulus and response of cardioinhibitory parasympathetic reflex?
- Stimulus: sudden rise in BP in carotid artery- Response: reduction in heart rate and force of contraction
113
Where are the ANS cardiac reflexes coordinated?
Cardiac center of medulla oblongata
114
Stimulus and response of cardioacceleratory sympathetic reflex?
- Stimulus: sudden decline in BP in carotid artery- Response: increase in heart rate and force of contraction
115
Stimulus and response of vasomotor sympathetic reflex?
- Stimulus: changes in BP in major arteries- Response: changes in diameter of peripheral vessels to maintain normal range of BPs
116
Where are the sympathetic vasomotor reflexes coordinated?
Vasomotor center of medulla oblongata
117
Can you consciously regulate the ANS?
YUP
118
What are 2 examples of the conscious regulation of the ANS?
1. Waiting to pee2. Cheating a lie detector test
119
What brain structure mediates communication between the cerebral cortex and the hypo?
Limbic system
120
What is hyperpyrexia? 2 other names?Treatment?
Dilated veins in the face in response to stress/sympathetic stimulation = red burning face = facial blushingTreatment = ablate the sympathetic nerves innervating the facial veins
121
What are the ONLY veins in the body that respond to sympathetic innervation BY DILATING?
Facial veins
122
What is hyperhidrosis? Diagnostic test? Treatments?
Overactive sympathetic NS causing excessive sweating of the hands Test = place mixture of starch, alizarin red, and sodium carbonate on palms and elevate patient's core temperature - indicator color will go from light orange to purple if positiveTreatments = 1. Bilateral endoscopic thoracic sympathectomy (ETS): ablate the sympathetic trunk at T3/T4 (but risk of many complications because have to cause pneumothorax to reach the sympathetic chain aka pierce the pleura and compensatory sweating in other places like the back) 2. Botox injections in armpits ever 3/4 months to eliminate autonomic nerves to the hands
123
What % of the Asian population has hyperhidrosis?
20%
124
Describe the embryonic development of sympathetic structures.
Specialized neural crest cells migrate to prevertebral ganglia and then settle in GIT
125
What is Hirschsprung's disease? Treatment?
Neural crest cells destined for the GIT fail to migrate during embryonic development causing a genetic birth defect where parasympathetic innervation of the distal end of the colon fails to develop => feces and gas accumulate proximal to the affected bowel segment causing tremendous distention/hypertrophy of the bowels Treatment = surgery to remove that part of the colon
126
What is Reynaud's disease? Cause? Treatment
Intermittent attacks during which skin of fingers and toes becomes pale and then blue (cyanotic) and painful due to exposure to cold and emotional stress (after attacks the vessels fill with blood again)Cause = exaggerated sympathetic vasoconstriction response in affected regionsTreatment = drugs that inhibit vasoconstriction but severe cases may require ganglia removal
127
Describe the severity of Reynaud's disease.
Varies
128
Potential complication of Reynaud's disease?
Gangrene
129
% of elderly affected by Reynaud's disease?
9% elderly women3-5% elderly men
130
Why do vessels of extremities constrict when we are cold?
To make sure our core and brain are not cold
131
What is HT brought on by?
Overactive sympathetic vasoconstriction from continual stress
132
2 complications of HT?
1. Increases work load on heart, possibly precipitating heart attack2. Increases wear/tear on vessels
133
Stress induced HT treatment?
Drugs that inhibit binding of NE and EPI to smooth muscle cells of blood vessels
134
What is achalasia? Diagnosis? Treatment?
Impaired autonomic innervation of esophagus resulting in loss of ability to propel food inferiorly and food cannot enter the stomachDiagnosis: barium orally for imagingTreatment = longitudinal incision through muscle at inferior end of esophagus OR dilation of lower esophageal sphincter with a balloon
135
Do beta-adrenergic receptors play a role in vasoconstriction?
NOPE
136
Receptors for vasoconstriction?
Alpha adrenergic
137
To what 3 plexuses do the sympathetic sacral splanchnics go to?
1. Inferior mesenteric2. Aortic3. Hypogastric
138
To what 2 plexuses do the sympathetic thoracic and lumbar (abdominal) splanchnics go to?
1. Aortic2. Superior mesenteric
139
Other name for sympathetic thoracic and lumbar splanchnics?
Abdominal sympathetic splanchnics
140
What do we call the intramural parasympathetic ganglion where the pre and postganglionic neurons synapse going to the parotid gland?
Otic ganglion
141
What do we call the intramural parasympathetic ganglion where the pre and postganglionic neurons synapse going to the submandibular and sublingual glands?
Submandibular ganglion
142
What do we call the intramural parasympathetic ganglion where the pre and postganglionic neurons synapse going to the lacrimal and nasal glands?
Pterygopalatine ganglion
143
What 4 organs does the hypogastric plexus innervate?
1. Large intestine (para only)2. Rectum (para only)3. Urinary bladder + ureters 4. Sex organs
144
Is the vagus nerve a pre or postganglionic nerve?
Preganglionic
145
What kind of thoracic splanchnic innervates the adrenal glands?
Greater thoracic splanchnic
