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RHSC 420 > Visceral Nervous System > Flashcards

Visceral Nervous System Flashcards

1
Q

What is another term for the motor portion of the visceral nervous system?

A

Autonomic NS

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2
Q

What spinal levels is the sympathic nervous system at?

A

T1-L2

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3
Q

What spinal levels is the parasympathetic nervous system at?

A

Brainstem + cranial nerves

S2-S4

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4
Q

How does the distribution of sympathetic vs. parasympathetic innervation differ in the body?

A

Sympathetic goes everywhere
Parasympathetic doesn’t go to the periphery!

In other words - the core has both sympathetic and parasympathetic innervation, but the extremities only have sympathetic innervation

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5
Q

Where are preganglionic sympathetic neurons found?

A

In the lateral horns of the SC from T1-L2

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6
Q

Describe the location of sympathetic Ganglia with relation to distance from SC and distance from target organ

A

Sympathetic ganglia are far from their target organ and close the spinal cord (sympathetic chain)

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7
Q

As a rule, where are MOST pre-ganglionic and postganglionic neurons found (for both sympathetic and parasympathetic?)

A

Preganglionic neurons are found inside the CNS, postganglionic are found outside the CNS with cell body in a ganglion

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8
Q

Which sympathetic ganglia do not lie within the sympathetic chain?

A

Prevertebral, or pre-aortic ganglia (they are close to the aorta) - the neurons travel through the sympathetic chain without synapsing to get to the prevertebral ganglia and synapse

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9
Q

What regions do the pre-aortic ganglia go to? What about the sympathetic chain ganglia?

A

Pre-aortic = abdominal and pelvic viscera

Sympathetic chain = thorax and limbs

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10
Q

In the sympathetic NS, pre-ganglionic neurons release ___________ and post-ganglionic neurons release ___________ .

A

acetylcholine, adrenaline or noradrenaline

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11
Q

Describe the location of parasympathetic Ganglia with relation to distance from SC and distance from target organ

A

Parasympathetic ganglia are found far from the spinal cord and close to their target organ

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12
Q

Which sympathetic organ is considered a misplaced sympathetic ganglion?

A

The adrenal medulla - it is directly innervated by a preganglionic sympathetic neuron

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13
Q

Give some examples of when the sympathetic and parasympathetic nervous systems are not working anatagonistically (which they usually do)?

A

Sexual function - they work together

Blood vessels - only receive sympathetic stimulation

Salivary gland secretion - only parasymp. stim.

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14
Q

Why is it called the parasympathetic NS?

A

Because “para” = around - the parasympathetics are situated around the sympathetics

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15
Q

Where do pre-ganglionic parasympathetic fibers come from?

A

Specific brainstem nuclei, or lateral horn of the spinal cord at level S2-S4

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16
Q

What neurotransmitters are used in the parasympathetic NS?

A 
Preganglionic = Ach
Postganglionic = Ach
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17
Q

What is the overall role of the parasympathetic nervous system?

A

Enhance energy storage

18
Q

What is the main function of the autonomic nervous system?

A

To maintain homeostasis

19
Q

How does the autonomic nervous system maintain homeostasis?

A

It integrates with the endocrine system (hypothalamus integrates)

20
Q

Give some examples of symp. and parasymp. working antagonistically

A 
Symp = increase HR, promote bowel filling
Parasymp = decrease HR, promote bowel emptying
21
Q

How do the sympathetic and parasympathetic NS work together for sexual function?

A

Parasymp - promote erection

Symp - ejaculation

22
Q

how does the parasympathetic nervous system decrease HR?

A

Signal is sent to dorsal motor nucleus and nucleus ambiguus of vagus nerve -> vagus nerve to heart

23
Q

How does the parasympathetic NS decrease blood pressure?

A

By decreasing heart rate and force of contraction -> this decreases cardiac output -> decreased BP

24
Q

What spinal levels promote increased HR in the sympathetic NS?

A

T1-T4

25
Q

How do the carotid sinus reflexe work?

A

Visceral sensory neurons (baroreceptors) in carotid sinus and aortic arch sense changes in BP -> info is sent to CN IX and X -> reaches brainstem nuclei -> CN IX and X send motor response to either increase or decrease HR -> @ same time, the opposite system will be inhibited -> results in either increased or decreased BP

26
Q

What causes Horner’s Syndrome?

A

Lack of sympathetic outflow to the head

Damage to T1 up to the ganglia in the head (because T1 controls sympathetic outflow to the head)

27
Q

What are the sx. or Horner’s syndrome?

A

Ptosis - droopy eyelid
Anhydrosis - not sweating
Miosis - constriction of pupil
Vasodilation of skin arterioles

28
Q

Who is at highest risk of Autonomic Dysreflexia?

A

Those with cervical injuries, but can happen to anyone with SCI T6 or higher

29
Q

What is the trigger for autonomic dysreflexia? How does the body respond? What are the symptoms?

A

1) Trigger is a noxious stimulus BELOW the level of SCI
2) Stimulus activates symp. NS and BP increases (below the level of injury) -> there is no cortical inhibition so BP really increases -> results in sweating, extremely high BP, erythema (redness), and headache

30
Q

What are some things that can cause Autonomic Dysreflexia?

A

UTI, urinary retention, blocked catheter, kidney stones, fecal impaction or fissures in bowel, pressure ulcers in skin

31
Q

What parts of the nervous system are involved in the urinary system? what are their roles?

A

Parasympathetic = visceral sensory neurons send bladder fullness signal -> goes to spinal cord and then to both parasympathetic preganglionic neuron and somatic motor neuron -> message goes to the Pontine Mictruition Center, but also can complete reflex arc without -> contraction of detrusser muscle when bladder is completely full (only activated when completely full)

Sympathetic = in those with prostates, it keeps the internal urethral sphincter closed to prevent backflow during ejaculation - this is inhibited when there is a full bladder

Somatic - conscious control over the timing of bladder emptying - somatic NS innervates the external urethral sphincter

32
Q

When the bladder is ready to empty the parasympathetic NS receives ___________ signals and the symp NS receives _________ signals

A

excitatory, inhibitory

33
Q

What is the role of the PMC in bladder emptying?

A

Coordinate inhibition of symp, excitation of parasymp, and inhibition of somatic motor during bladder emptying

34
Q

What can cause hyperreflexive (spastic) bladder? Explain the mechanisms. What are the symptoms of spastic bladder?

A

Damage above S2

Still have reflex emptying of bladder due to parasympathetic reflex arc - detruser muscle contracts when bladder is full

No longer have cortical control over somatic neurons below level of damage (i.e. cannot control somatics at S2-S4) so unable to relax EUS (no inhibition, high tone)

Results in incomplete emptying and backflow of urine which can cause chronic UTIs, can also result in overflow incontinence

35
Q

What can cause areflexive bladder? What are the mechanisms and symptoms?

A

SC damage at S2-S4 (including cauda equina)

Reflex arc is damaged - unable to contract detruser muscle, it is flaccid. The somatic MNs innervating the EUS are damaged which results in flaccid EUS.

Result is constant dribbling of urine.

36
Q

What parts of the NS are involved in bowel control? What are their roles?

A

Parasympathetic - vagus nerve innervates the upper and midgut, S2-S4 innervates the hindgut and internal anal sphincter - parasympathetic activation causes gut peristalsis and secretions, and relaxation of the internal anal sphincter

Sympathetic - L1 and L2 (or T5 to L2, UNCLEAR?) - prevents peristalsis and tightens internal anal sphincter

Somatic - conscious control over external anal sphincter and abdominal muscles

37
Q

Describe the symptoms and mechanisms of hyperreflexive bowel (AKA UMN bowel syndrome)

A

Damage above S2-S4

  • Parasympathetics can still reflexively do peristalsis
  • Not cortical input to somatic motor system, so the external anal sphincter has high tone and cannot be inhibited
  • Results in some constipation
  • Often can have BM with digital stim.
38
Q

Describe the symptoms and mechanisms of areflexive bowel (AKA LMN bowel syndrome)

A

Damage to S2-S4 LMN results in inability to do peristalsis in hindgut. Also, somatic innervation to external anal sphincter is damaged, so cannot tighten it. Leads to high degree of constipation, and incontinence when fecal matter reaches EAS

39
Q

Describe the roles of the sympathetic and parasympathetic nervous systems in sexual function

A

Parasympathetic (S2-S4):

  • erection
  • sexual secretions

Sympathetic (T10-L2):

  • decrease psychogenic arousal
  • inhibiting parasympathetics
  • vaginal and vas deferens contractions
  • ejaculation
40
Q

Describe the impacts of different levels of injury on sexual function

A

1) Above T10 - no psychogenic erection (can get reflex erection)
2) At L1-L2 - no ejaculation
3) Above L1 - reflex ejaculation is possible
4) At S2-S4 - no reflex erection, can get psychogenic erection

41
Q

How does referred pain work?

A

Visceral nervous system sends pain signal to dermatome from same spinal level that innervate the internal organ that is in pain

42
Q

What is the name of the condition that results form disruption to sympathetic outflow to the head?

A

Horner’s Syndrome

RHSC 420 (13 decks)

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