regulation of GI function Flashcards

1
Q

what is the enteric nervous system

A

short reflex arcs located within wall of GI tract and can operate independently of rest of body
has sensory and motor cells

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2
Q

what do simple reflex arcs consist of

A

single sensory cell and a single motor nerve cell.

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3
Q

what do complex reflex arcs consist of

A

single reflex arcs connected by interneurons

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4
Q

what do short reflex arcs enable

A

enable GI tract to have extensive control of its activities

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5
Q

what is the main transmitter of reflex arcs

A

acetylcholine

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6
Q

what does the parasympathetic system promote

A

digestion

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7
Q

where are pre-ganglionic fibres located (parasympathetic)

A

vagus nerve

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8
Q

where are post ganglionic fibres located (parasympathetic)

A

embedded in the wall of the GI tract and connect to the enteric nervous system

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9
Q

where are pre-ganglionic fibres located in the sympathetic NS

A

run in splanchnic nerves

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10
Q

what is the transmitter of pre-ganglionic fibres in SNS

A

acetylcholine

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11
Q

where are post-ganglionic fibres located in SNS

A

run along arteries to organ of innervation or in hypogastric nerves

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12
Q

what is the transmitter of post-ganglionic in SNS and function

A

noradrenaline to inhibit secretion, motility and decrease blood supply to the GI tract

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13
Q

what do entero-enteric reflexes do

A

co-ordinate activity between different parts of the GI tract

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14
Q

where is the production site of the hormone gastrin

A

caudal stomach

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15
Q

what is the stimulation of hormone Gastrin

A

peptides and amino acids
acetylcholine

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16
Q

what effect does the hormone Gastrin have

A

stimulates HCL, stimulates grown of gastric/intestinal mucosa

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17
Q

production site of secretin

A

duodenum

18
Q

what is the stimulation of secretin

A

HCL

19
Q

effect of secretin

A

stimulates pancreatic HCO3-

20
Q

production site of CCK

A

duodenum

21
Q

stimulation of CCK

A

fatty acids, monoglycerides, amino acids, peptides

22
Q

effect of CCK

A

stimulates pancreatic enzymes
contracts gall bladder

23
Q

production site of Gastric Inhibitory Peptide (GIP)

A

cranial small intestine

24
Q

stimulation of GIP

A

fat, glucose, amino acids

25
Q

effect of GIP

A

inhibits HCL
stimulates insulin production

26
Q

what are the 3 phases of regulation

A

cephalic phase - head
gastric phase - stomach
intestinal phase - intetines

27
Q

what is the cephalic phase co-oridinated by

A

ANS

28
Q

what is the gastric phase co-ordinated by

A

ANS, ENS and hormones - gastrin

29
Q

what is the intestinal phase co-ordinated by

A

ANS, ENS, and hormones - secretin, CCK and GIP

30
Q

what is the regulation of appetite controlled by in the brain

A

hypothalamus

31
Q

what does the appetite centre do

A

causes food searching and voracious eating
direct effect on animals behaviour

32
Q

what does the satiety centre do

A

causes refusal of food
inhibits appetite centre

33
Q

what are the 3 theories of mechanism of action

A

glucostat
cck
lipostat

34
Q

what is motility

A

co-ordinated contraction of smooth muscle in the GI tract

35
Q

what are the 4 types of contraction

A

segmental
peristalsis
anti-peristalsis
mass movement

36
Q

what is segmental contraction

A

mixes lumen contents
mechanical breakdown

37
Q

what is peristalsis

A

move intestinal contents in a gradual aboral direction

38
Q

what is anti-peristalsis

A

moves intestinal contents in an oral direction eg rumination/vomiting

39
Q

what is mass movement

A

empties entire sections of GI tract
eg evacuate colon contents into rectum prior to defaecation

40
Q

what happens when pacemaker cells reach threshold potential

A

action potential to cause smooth muscle contraction

41
Q

what determines strength of contraction

A

frequency of action potentials

42
Q

what are action potentials due to

A

opening of calcium channels