Neuro: 4.2 - Autonomic Nervous System

Front 1

What are the functions of the ANS?

Back 1

- Maintain homeostasis
- Emergency responses
- Facilitate reproduction function

Front 2

What is the modality of the ANS?

Back 2

Visceral Motor

Front 3

What are some target organs innervated by the ANS?

Back 3

- Cardiac muscle
- Smooth muscle
- Glands

Front 4

What are the divisions of the ANS?

Back 4

- Sympathetic
- Parasympathetic
- Enteric

Front 5

What are the NT used by the preganglionic and postganglionic Sympathetic neurons?

Back 5

- Preganglionic: ACh
- Postganglionic: mostly NE, but on sweat glands and vasodilator fibers ACh

Front 6

What are the NT used by the preganglionic and postganglionic Parasympathetic neurons?

Back 6

- Preganglionic: ACh
- Postganglionic: ACh

Front 7

What is the relative divergence of the sympathetic vs parasympathetic fibers? Which has more divergence?

Back 7

- SNS: 1:10
- PNS: 1:3
* Sympathetic has more divergence

Front 8

What is the length of preganglionic and postganglionic fibers in the SNS?

Back 8

- Pre: short
- Post: long

Front 9

What is the length of preganglionic and postganglionic fibers in the PNS?

Back 9

- Pre: long
- Post: short

Front 10

Sympathetic fibers leave the spinal cord at what levels?

Back 10

Thoracolumbar: T1-L2

Front 11

Parasympathetic fibers leave the spinal cord at what levels?

Back 11

Craniosacral: CN III, VII, IX, X; S2-S4

Front 12

Which cranial nerves have parasympathetic function?

Back 12

CN III, VII, IX, X

Front 13

What are the four courses of a sympathetic preganglionic axon?

Back 13

1. Establish synaptic contact with postganglionic neuron in paravertebral chain (sympathetic trunk) at same level
2. Pass up or down sympathetic trunk to synapse on postganglionic neuron at different level
3. Pass through paravertebral ganglion to contact postganglionic neuron in a prevertebral ganglion (celiac, sup. or inf. mesenteric)
4. Pass through paravertebral ganglion en route to adrenal medulla

Front 14

CN III - Oculomotor:
- Brainstem Nuclei
- Peripheral Ganglia
- Target Organ

Back 14

- Edinger-Westphal Nucleus
- Ciliary Ganglia
- Sphincter Pupillae m.

Front 15

CN VII - Facial:
- Brainstem Nuclei
- Peripheral Ganglia
- Target Organ

Back 15

- Superior Salivatory Nucleus
- Pterygopalatine Ganglia --> Lacrimal Gland (crying)
- Submandibular Ganglia --> Sublingual and Submandibular (saliva)

Front 16

CN IX - Glossopharyngeal:
- Brainstem Nuclei
- Peripheral Ganglia
- Target Organ

Back 16

- Inferior Salivatory Nucleus
- Otic Ganglia
- Parotid Gland (saliva)

Front 17

CN X - Vagus:
- Brainstem Nuclei
- Peripheral Ganglia
- Target Organ

Back 17

- Dorsal Motor Nucleus
- Myenteric and Submucosal (terminal) Ganglia
- Smooth muscle and glands of GI tract

Front 18

What are the symptoms of Vasovagal Syncope?

Back 18

1. Muscle weakness
2. Warm sensation
3. Nausea
4. Sweating

Front 19

What is the possible explanation for Vasovagal Syncope?

Back 19

- Peripheral venous pooling -->
- Splanchnic pooling activates low pressure mechanoreceptors (interpreted by brain as increased venous pressure) -->
- Withdrawal of sympathetic activity and increase in vagal activity -->
- Inappropriate peripheral vasodilation and bradycardia -->
- Hypotension and syncope

Front 20

What are the ANS components of the baroreceptor reflex?

Back 20

- Stretch receptors in carotid sinus (IX) and aortic arch (X)
- Glossopharyngeal n. (IX) and vagus n. (X) provide afferent limb
- CNS processing in nucleus solitarius
- Efferent limb: PNS axons of CN X from neurons in dorsal motor nucleus (cardioinhibitory)
- Efferent limb: SNS interomediolateral cell column of spinal cord (cardiostimulatory and pressor responses)

Front 21

What ANS receptors are involved in the baroreceptor reflex?

Back 21

Stretch receptors in carotid sinus (IX) and aortic arch (X)

Front 22

What nerve carries the afferent information for the baroreceptor reflex?

Back 22

Glossopharyngeal (IX) and Vagus (X)

Front 23

Where is the baroreceptor reflex processed?

Back 23

In the CNS - Nucleus Solitarius

Front 24

What nerve carries the efferent information for the baroreceptor reflex?

Back 24

- PNS: axons of Vagus (X) from neurons in dorsal motor nucleus (cardioinhibitory)
- SNS: interomediolateral cell column of spinal cord (cardiostimulatory and pressor response)

Front 25

What are the symptoms of Horner's Syndrome?

Back 25

- Ptosis (drooping eyelid)
- Miosis (constriction of pupil)
- Anhidrosis (inability to sweat)
- Enophthalmos (posterior displacement of eyeball within orbit due to ptosis)

Front 26

What is the cause of Horner's Syndrome?

Back 26

- Loss of sympathetic innervation (dilator pupillae m., superior tarsal m., facial sweat glands)
- Cervical sympathetic pathway from hypothalamus is interrupted (may be central, preganglionic, or postganglionic in origin)

Front 27

In what Syndrome is Horner's Syndrome a part of?

Back 27

Part of Lateral Medullary Syndrome, AKA Wallenberg Syndrome

Front 28

What is the other name for Lateral Medullary Syndrome? Symptoms?

Back 28

- Wallenberg Syndrome
- Dysarthria
- Dysphagia
- Contralateral loss of pain and temperature
- Ipsilateral loss of facial sensation
- Horner's Syndrome (ptosis, miosis, anhydrosis, enopthalmos)

Front 29

Autnomic Dysreflexia affects people with spinal cord injuries at what level?

Back 29

T5 and above

Front 30

What is the cause of Autonomic Dysreflexia?

Back 30

Disordered autonomic response - causes sympathetic hyperreflexia

Front 31

What kind of stimulus can trigger Autonomic Dysreflexia?

Back 31

Overfull bladder (blocked catheter) or noxious stimulus --> Causes activation of sympathetic outflow

Front 32

What are some symptoms of Autonomic Dysreflexia following a spinal cord injury?

Back 32

- Headache
- Hypertension
- Bradycardia
- Piloerection
- Pallor
- Can be life-threatening

Front 33

What is the route for controlling micturition (urination)?

Back 33

S2-S4 --> Pelvic Splanchnic nerves --> Inferior Hypogastric Plexus --> Postganglionic Fibers --> Detrussor Muscle --> Contraction (Micturition)

Front 34

What is the route for controlling urinary storage?

Back 34

1) Interomediolateral cell column (T11-L2) --> Lumbar Splanchnic Nerves --> Internal Urethral Sphincter --> Contraction --> Storage
2) Somatic Motor Innervation (S2-S4 / Pudendal n.) --> External Urethral Sphincter --> Contraction --> Storage

Front 35

How is male reproductive function controlled by the ANS?

Back 35

- Sexual stimulation --> Erection (vascular and controlled by PNS)
- Ejaculation --> Emission and ejaculation (controlled by SNS and somatic control)

Front 36

How is female reproductive function controlled by the ANS?

Back 36

- External genitalia by ilioinguinal and perineal nerves (somatic)
- Internal reproductive structures receive not only autonomic innervation, but also regulated by hormones

Front 37

What is the cause of Hirschprung's Disease?

Back 37

- Congenital absence of myenteric (Auerbach's) plexus
- Failure to produce ganglion cells located between layers of muscularis externa
- No peristalsis in denervated colon (appears small) compared to proximal part of colon which becomes distended

Front 38

What are the symptoms of Hirschprung's Disease? Treatment?

Back 38

- Constipation
- Surgically attach normal colon to rectum