Regulation of gastrointestinal function Flashcards

1
Q

Name the 2 plexuses involved in intrinsic (enteric) nervous and endocrine control.

A

Myenteric (auerbach’s) plexus
Submucosal (Meissner’s) plexus

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2
Q

Stimulation of the myenteric plexus causes?

A

Peristalsis, contractions along the whole GIT

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3
Q

Stimulation of the Meissner’s plexus causes?

A

Secretions

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4
Q

Name the 3 components of the intrinsic enteric nervous system

A

Meissner’s (submucosal) plexus
Myenteric (auerbach’s) plexus
Enteroendocrine cells in mucosa/ pancreas

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5
Q

Name and describe the 2 types of sensory (afferent) neurons.

A

Mechanoreceptors: within smooth muscle layers, measures gut distension
Chemoreceptors: within mucosa, measure chemical conditions in the lumen of the gut (e.g. peptides, pH)

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6
Q

Describe interneurons

A

Travel long distances within the MYENTERIC PLEXUS (AUERBACH’S PLEXUS) and connect the myenteric and submucosal (meissners) plexus

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7
Q

List the excitatory neurocrine neurotransmitters

A

Cholinergic (secrete Ach)
peptide substances

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8
Q

List the inhibitory neurocrine transmitters

A

Peptides - somatostatin
Nitric oxide, ATP

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9
Q

Name a dual purpose peptide and its actions

A

Vasoactive intestinal peptide (VIP) which inhibits smooth muscle, and stimulates

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10
Q

List the 2 true endocrine hormones., why are these considered true hormones

A

Somatostatin and gastrin, true hormones as they have to travel via blood

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11
Q

What do enterochromaffin cells secrete

A

Secretin

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12
Q

Explain the process of paracrine secretion.

A

Cell targeting a nearby cell (no blood required)

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13
Q

Explain the process of endocrine secretion.

A

Cell targeting a distant cell via a bloodstream

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14
Q

Explain the process of holocrine secretion.

A

Cell breaking apart to release its contents

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15
Q

What hormone acts as a paracrine molecule?

A

Somatostatin

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16
Q

What nerve is the main supply for the GIT, and what is the common term for it?

A

CNX, vagus nerve

17
Q

What additional nerve supplies some of the caudal GIT?

A

Pelvic nerve

18
Q

Name the 3 sympathetic innervation (ganglia) to the GIT

A

coeliac, cranial mesenteric ganglion, caudal mesenteric ganglion

19
Q

What are 2 locations postganglionic fibres will synapse with in the sympathetic nervous system?

A

The ENS or to the smooth muscle/ glands directly

20
Q

Is the sympathetic innervation usually inhibitory/ excitatory? why?

A

Inhibitory, as its related to the stress response fight/ flight

21
Q

What are the effects on the gut from sympathetic nerve stimulation? what benefit does this serve?

A

Decreased motility, decreased blood flow to the area, decreased secretion. Allows the animal to direct more energy to the fight/ flight stimuli

22
Q

Describe the trophic effect.

A

An increase in food intake results in an increase of regulatory protein released (e.g. gastrin -> increases HCl secretion). This increases the amount of food that can be digested/ absorbed