Lecture 15: Enteric Nervous System (Sanchez) Flashcards Preview

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Flashcards in Lecture 15: Enteric Nervous System (Sanchez) Deck (26)
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1
Q

explain the 3 divisions of the ANS to the GI tract

A

1) sympathetic (via thoracolumbar divisions)
2) enteric (via submucous-myenteric plexuses)
3) parasympathetic (via cranio-sacral divisions)

2
Q

where does the myenteric ganglion of the enteric nervous system reside?

A

between circular and longitudinal muscles of the GI tract

3
Q

motor innervation of the myenteric plexus

A

circular and longitudinal muscles

4
Q

secretomotor innervation of the myenteric plexus

A

mucosa

5
Q

Where do the projections of the myenteric plexus extend?

A

submucosal ganglia, enteric ganglia of gall bladder, sympathetic ganglia

6
Q

major function of the submucous plexus

A

intestinal secretion

7
Q

innervation of the submucous plexus

A

muscularis mucosa, intestinal endocrine cells, submucosal vasculature

8
Q

3 types of sensory receptors

A

mechanoreceptors, chemoreceptors, and thermoreceptors

9
Q

what do mechanoreceptors of the GI tract detect?

A

muscular stretch, villous distortion, mucosal motion

10
Q

what do chemoreceptors of the GI tract detect?

A

acid, amino acids, lipid, glucose, osmolarity of meal

11
Q

intrinsic primary afferent neurons

A

neurons that remain intrinsic and modulate GI activity at a local reflex level

12
Q

extrinsic primary afferent neurons

A

neurons that project from the GI tract to the brainstem via the vagus n, or to the spinal cord via the dorsal root ganglion to initiate central modulatory responses

13
Q

prominent peptides involved in afferent neural transmission

A

serotonin, substance P, and CGRP

14
Q

Where do enteric motor neurons arise?

A

brainstem (for parasymp.) or spinal cord (for symp.)

15
Q

Explain pathway of splanchnic nerve transmission

A

visceral sensory receptor –> primary afferent fiber –> dorsal root gangion –> synapses on sympathetic neuron –> symp. preganglionic fiber –> paravertebral ganglion –> prevertebral ganglion –> symp. postganglionic neuron

16
Q

pathway of vagal n. transmission

A

afferent sensory –> nucleus tractus solitarius in medulla –> synapses on dorsal motor nucleus and nucleus ambiguus –> descending efferent motor nerves

17
Q

primary inhibitory neurotransmitters in PARASYMPATHETIC enteric nervous system

A

VIP, nitric oxide

18
Q

stimulatory neurotransmitters in parasympathetic enteric nervous system

A

substance P, Ach. Substance P causes contraction, Ach causes relaxation.

19
Q

primary inhibitory NT in SYMPATHETIC enteric nervous system

A

NE

20
Q

Where do sympathetic enteric motor neurons synapse?

A

within paravertebral ganglia. (They are post-ganglionic fibers)

21
Q

default state of circular muscle intrinsic primary afferent neurons?

A

relaxed. Activation via ascending excitatory reflex results in contraction proximally, and distal relaxation via descending inhibitory reflex to move ingesta through the GI tract

22
Q

hypersensitivity

A

alteration in pain threshold; an extenuated pain reflex

23
Q

allodynia

A

when something that normally isn’t painful becomes painful

24
Q

ileus

A

general term for decreased motility in GI tract. Can be from inflammation, pain, etc.

25
Q

colic

A

general term for abdominal pain

26
Q

inflammation –> GI motility

A

decreases

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