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GI week 2 > Gastic secretion > Flashcards

Gastic secretion Flashcards

1
Q

How does the stomach participate in protein digestion>

A

acid hydrolysis and pepsin cleavage

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2
Q

How does the contents from the stomach enter the SI?

A

at a controlled rate to optizmize further digestion and absoprtion

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3
Q

Bezoar

A

ball of foreign material trapped in stomach (hairball)

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4
Q

Emesis

A

Vomiting, forcible ejection of stomach contents through the mouth

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5
Q

Dyspepsia

A

indigestion, pain in upper abdomen after eating

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6
Q

Gastroparesis

A

delayed emptying

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7
Q

Migrating Motor Complex

A

clears undigested material from the GI tract

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8
Q

Regurgitation

A

flow of material that has not reached the stomach back up the esophagus

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9
Q

Rugae

A

Stomach folds which expand as stomach fills

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10
Q

Scintigraphy

A

using a dual-radiolabeled solid and nutrient liquid meal, to measure gastric emptying

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11
Q

Trituration

A

grinding of food into small molecules

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12
Q

Paritel cell secretes

A

HCL, IF (for B12 absoprtion in the ileum)

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13
Q

Chief cells secrete

A

pepsinogen for protien digestion

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14
Q

surface mucous cells secrete

A

mucus, HCO3 fir gastroprotection

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15
Q

G cells in the antrum secrets

A

gastrin which activate parietall cells in the fundus to secrete acid

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16
Q

What kind of receptor does gastrin bind to

A

CCK2

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17
Q

what triggers gastrin release from the g cells in teh antrum?

A

seeing food or stomach distention causes vagal stimulation, causing gastrin releasing peptide, aromatic AA in the lumen

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18
Q

What activates parietal cells?

A

gastrin, histamine, and AcH

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19
Q

What activates ECL cells?

A

AcH, gastrin

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20
Q

ECL cells release what?

A

histamine which then binds to parietal cells

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21
Q

What happens upon parietal stimulation?

A

tubulovesicular membranes fuse with canalicular membranes increasing the density of H+, K+ ATPase molecules at the apical membrane.

22
Q

Describe the ion transport of the parietal cells

A

Protons are made in the cytosol and pumped out via - H+, K+ ATPase into the lumen, bicarb in exported in from the basolateral (blood) side by vesiscular fusion/CH/HCO3 exchanger and enters blood stream

23
Q

How does Cl move during parietal cell stimulation>

A

passive from basolateral side to lumen, water follows

24
Q

What is the electrical potential exists across the gastric mucosa at rest? during activation?

A

-70, -30

25
Q

What inhibits gastrin release?

A

somatostatin which is secreted from D cells in the atrum when the pH is <3

26
Q

What happens during the gastric phase?

A

You get an icnrease in pH due to food which decreases somatosatin secretion

27
Q

what does somatisatin inhibit?

A

Inhibits formation of cAMP(prostiglandins also do this) via a Gi-dependent signaling pathway in parietal cells,
indirectly inhibits ECL secretion of histamine,
G cells release of gastrin

28
Q

What does the feedback from the duodenum do to parietal cells

A

nervous reflux blocks activation of parietal cells, enterogastrones like secretin block secretion of histamine by ECL cells

29
Q

What is the Interdigestive Phase

A

Low acid secretion, D cells secrete somatostatin to maintain low levels of Gastrin

30
Q

Cephalic Phase

A

dorsal vagal complex integrates input from higher centers (seeing and tasting food) to activate Vagus nerves. GRP activates gastrin release and Ach activates ECL and parietal cells.

31
Q

Gastric Phase

A

distension of the stomach activates vagal afferents and the enteric nervous system. Amino acids activate gastrin secretion and food raises pH decreasing somatostatin secretion.

32
Q

Intestinal Phase

A

introduction of the gastric contents into the small intestine activates duodenal G cell secretion of gastrin. Activation of secretin and other enterogastrones and neural reflex decreases secretion.

33
Q

Do PPI have an effect on intrsic factor?

A

NO! can still absorb b12

34
Q

What can cause a lack of B12 absoportion

A

autoimmune destriction of parietal cells, BYPASS SURGERY! can get megablastic anemia and neurological defects

35
Q

What secretes pepsinogen? in response to what

A

chief cells, AcH and gastrin,

36
Q

what inhibits pepsingen secretion?

A

secretin

37
Q

what kind of molecule is pepsinogen

A

inactive prozyme proteases, activated by acid

38
Q

what kind of molecule is pepsin

A

endopeptidase, can further activate pepsinogen by autolysis

39
Q

What do surface epithelial cells secrete?

A

mucus and bicarb in response to PGE2

40
Q

What effect does NSAIDS have on muscus seretion?

A

It decreases it since it blocks PGE2, this contributes to gastric irritation

41
Q

What can catecholamines do to gastric mucosa?

A

suppress bicarb secretion, this contributes to gastric ulcers- STRESS ULCERS!

42
Q

How do you regenerate disrupted epitheloum?

A

by using trefoil factors and growth factors

43
Q

What is Zollinger Ellison Syndrome?

A

its a gastrin secreting tumor in the pancrease or intestine, excess H secretion as well as hyperplasia and hypertrophy of parietal cells, treat with PPi?

44
Q

Peptic ulcer disease is due to?

A

hyperacidity, deterioration of the gastro musocsal barrier, get increase bleeding,

45
Q

Some causes of gastric and duedenal ulcers

A

Infection – Helicobactor pylori
Poor secretion of mucus, bicarbonate by the surface epithelium
Stress (may contribute but doesn’t cause)
Irritation by alcohol, acid, digestive enzymes, bile

46
Q

Tx ulcers with>

A

antibiotics (amoc/cipro) and proton pump inhibitor. Stop NSAID

47
Q

what is the pathophysiology of peptic ulcers?

A

increased gastin levels because somatostain is not active in fasting state, causes increase acid, pepsin, hyperplasa of ECL cells,

48
Q

Peptic ulcers in patients with hypochlohydria is related to?

A

gastritis and destruction of gastric epithelial cells, decrease of acid production?

49
Q

Achlorhydria is due to

A

reduced acid secretion, caused by aging, autoimmune attack of H/K atpase, PPI, infection, atropic gastritis,

50
Q

Side effects of achlorhydria?

A

increase bacteria growth, HIP fractures due to decrease CA, FE def anemia, decreased pep, increased diarrhea

GI week 2 (8 decks)

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