Lecture 15: Enteric Nervous System (Sanchez) Flashcards Preview

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

explain the 3 divisions of the ANS to the GI tract

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

2

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

between circular and longitudinal muscles of the GI tract

3

motor innervation of the myenteric plexus

circular and longitudinal muscles

4

secretomotor innervation of the myenteric plexus

mucosa

5

Where do the projections of the myenteric plexus extend?

submucosal ganglia, enteric ganglia of gall bladder, sympathetic ganglia

6

major function of the submucous plexus

intestinal secretion

7

innervation of the submucous plexus

muscularis mucosa, intestinal endocrine cells, submucosal vasculature

8

3 types of sensory receptors

mechanoreceptors, chemoreceptors, and thermoreceptors

9

what do mechanoreceptors of the GI tract detect?

muscular stretch, villous distortion, mucosal motion

10

what do chemoreceptors of the GI tract detect?

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

11

intrinsic primary afferent neurons

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

12

extrinsic primary afferent neurons

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

prominent peptides involved in afferent neural transmission

serotonin, substance P, and CGRP

14

Where do enteric motor neurons arise?

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

15

Explain pathway of splanchnic nerve transmission

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

16

pathway of vagal n. transmission

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

17

primary inhibitory neurotransmitters in PARASYMPATHETIC enteric nervous system

VIP, nitric oxide

18

stimulatory neurotransmitters in parasympathetic enteric nervous system

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

19

primary inhibitory NT in SYMPATHETIC enteric nervous system

NE

20

Where do sympathetic enteric motor neurons synapse?

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

21

default state of circular muscle intrinsic primary afferent neurons?

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

hypersensitivity

alteration in pain threshold; an extenuated pain reflex

23

allodynia

when something that normally isn't painful becomes painful

24

ileus

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

25

colic

general term for abdominal pain

26

inflammation --> GI motility

decreases

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