Nutrient Sensing Flashcards

1
Q

what is required for gastric acid secretion

A

gastrin
histamine
ACh

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2
Q

steps in gastric acid secretion

A

gastrin activates endocrine cells
endocrine cells release histamine
histamine directed to parietal cells with contain a proton pump (Ca2+/cAMP dependent)
proton pump exchanges H+ out, K+ in causing gastric acid secretion
vagus nerve releases ACh
ACh activates Gq GPCR which activates the proton pump

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3
Q

what forms the mucus layer

A

biocarbonate ions and mucus
pH of 7

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4
Q

what is the role of the prostoglandin receptor

A

prevents proton pump activation

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5
Q

what do G cells contain

A

located in the stomach
contain gastrin

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6
Q

what do L cells contain

A

neurotensin/GIP/GLP-1/2/OXM/PYY (bowel)

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7
Q

what do EC cells contain

A

5-HT/SP/Histamine
(GI area)

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8
Q

PYY

A

pro absorptive
anti secretory (retains electrolytes and inhibits electrolyte secretion)
defends against diarrhoea
mediates ileum and colonic brakes (slows motiliy)

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9
Q

GLP

A

pro absorptive
slows gastric emptying
proliferative/anti-apoptotic in GI tract
controls blood glucose and insulin secretion (incretins)

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10
Q

GLP-1 vs GLP-2

A

GLP-1 reduces bodyweight
GLP-2 glucose sensing

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11
Q

how does GLP-2 sense glucose in the enteric secretomotor neurons

A

glucose stimulates tastant receptors TIR2
GLP-2 released
GLP-2 stimulates VIP to cause electrolyte secretion
VIP released from varicosities
cAMP-CFTR-Cl- release
counter ion/electrolyte movement

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12
Q

where is GPR119 expressed

A

highly in the pancreas and GI tract
insulin secretion
‘fat sensor’, sensing endogenous and luminal N-acylethanolamines

in mouse ileum»colon>SI

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13
Q

L cell activity

A

glucose dependent/inhibited by phloridzin = SGLT1 inhibitor

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14
Q

role of GPR119

A

reduces hyperglycemia
improves glucose tolerance
increases PYY/GLP-1/GIP release
fat sensor senses endogeneous lipids

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15
Q

FFA2 (GPR43)

A

ligands: SCFA (C2/3)
Gi/Gq coupled
PYY and GLP-1 release, satiety, anti-inflammatory,adipogenesis, inhibits lipolysis
in L cells

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16
Q

FFA3 (GPR41)

A

ligand: SCFA (C3-5)
Gi/Gq coupled
PYY and GLP-1 release, inhibits lipolysis, energy and glucose homeostasis
in enterocrine cells

17
Q

L cell activation

A

Bile acids activate TGR5/endogeneous lipids (2-MAG/2-OG) activate GPR119
increase in cAMP
PYY release - inhibits IPANs
GLP-1 release - activates CGRPs - electrolyte secretion
GLP-2 release

18
Q

ghrelin opposes GLP-1/PYY action

A

causes increases appetite/adiposity/gastric emptying/glucagon secretion
inhibits insulin secretion and thermogenesis

19
Q

FFA2 dual role

A

stimulates L cells to release PYY and GLP-1
inhibits ghrelin cells

20
Q

what occurs in RYGB (roux en Y gastric banding)

A

hypertrophy doubles L-cell number
increases PYY and PPG gene expression
alters intestinal metabolism