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GIGU > Secretions of GI Tract and Pancreas > Flashcards

Secretions of GI Tract and Pancreas Flashcards

1
Q

Saliva is produced by what?

A

Salivary glands - parotid, submandibular and sublingual

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2
Q

What glands secrete the most saliva?

A

Submandibular and sublingual

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3
Q

Describe the salivary gland structure

A

Acinar cells with myoepithelial cells surrounding

  • Connected to intercalated duct
  • Connected to striated duct
  • Connected to excretory duct
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4
Q

The acinar cells secrete an _____ solution

A

isotonic

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5
Q

What type of cells contract to help eject saliva from the gland?

A

Myoepithelial cells

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6
Q

What part of the salivary gland and what type of cells modify the initial saliva?

A

The striated duct and its ductal cells

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7
Q

The striated duct creates a _____ solution

A

hypotonic

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8
Q

Striated ductal cells are ______ to water

A

IMPERMEABLE = helps to create the hypotonic solution

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9
Q

Describe the electrolyte concentrations in the hypotonic saliva

A

INCREASED K+ and HCO3-

DECREASED Na+ and Cl-

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10
Q

The striated ductal cells _______ more Na+ and Cl-

A

Absorb

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11
Q

The striated ductal cells _____ less K+ and HCO3- into the lumen

A

Secrete

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12
Q

Describe the net absorption of the salivary ductal cells

A

The cells absorb MORE Na+ and Cl- than they secrete of K+ and HCO3-

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13
Q

What controls the salivary secretions?

A

Autonomic Nervous System (ANS)

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14
Q

Why is the control of salivary secretions unusual?

A

The parasympathetic system and the sympathetic system BOTH ACTIVATE the salivary secretions (normally oppose eachothers actions)

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15
Q

Parasympathetic or sympathetic.. which one dominates salivary secretion control?

A

Parasympathetics

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16
Q

What stimuli activates the Parasympathetics to increase saliva secretions?

A

Conditioning
Food, smell
Nausea

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17
Q

What stimuli inhibits the Parasympathetics to decrease saliva secretions?

A

Dehydration

Sleep, fear

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18
Q

CN ___ and ___ activate release of ____ to acinar or ductal cells in the salivary glands (parasymp.)

A

CN 7 and 9 activate release of Ach

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19
Q

Sympathetics T1-T3 activate release of ____ to acinar or ductal cells in the salivary glands

A

NE

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20
Q

What inhibits the parasympathetic release of Ach to the acinar or ductal cells in the salivary glands?

A

Atropine

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21
Q

What are the cells in the body of the stomach that secrete components of gastric juice?

A

Parietal cells

Chief cells

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22
Q

What do parietal cells release in the stomach?

A

HCl and Intrinsic factor

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23
Q

Why is it important for the parietal cells to release HCl?

A

Creates a very acidic environment which is required for pepsinogen to be converted to pepsin

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24
Q

Why is it important for the parietal cells to release Intrinsic factor?

A

For the absorption of Vitamin B12

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25
Q

What do chief cells release in the stomach?

A

Pepsinogen

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26
Q

What are the cells in the antrum of the stomach that secrete components of gastric juice?

A

G cells

Mucous cells

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27
Q

What do G cells release into circulation from the stomach?

A

Gastrin

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28
Q

What is secreted and absorbed from a parietal cell in the stomach?

A 
Secreted = H+ and Cl-
Absorbed = HCO3-
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29
Q

What can inhibit the secretion of H+ from parietal cells?

A

Omeprazole

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30
Q

Agents that can stimulate H+ secretion from gastric parietal cells

A

Vagus - ACh
G cells - Gastrin
ECL cells - Histamine

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31
Q

Agents that can inhibit H+ secretion from gastric parietal cells

A

Somatostatin

Prostaglandins

32
Q

What are the 2 ways the Vagus nerve can stimulate H+ secretion from gastric parietal cells?

A
  1. Direct - release Ach to parietal cells

2. Indirect - release GRP to G cells, which then release Gastrin into circulation, which then activates parietal cells

33
Q

Somatostatin can inhibit G cells from releasing Gastrin. When the pH falls to low (too much H+ secretion from parietal cells), what will activate somatostatin to inhibit them more?

A

Gastrin itself! (negative feedback)

34
Q

Atropine can block which vagus nerve pathway for stimulation of H+ secretion from parietal cells?

A

The direct pathway because it releases ACh

– The indirect pathway releases GRP which cannot be inhibited by Atropine

35
Q

What are the 3 phases of Gastric HCl secretion?

A

Cephalic phase
Gastric phase
Intestinal phase

36
Q

What can abolish the cephalic phase of gastric HCl secretion?

A

Vagotomy

37
Q

Which phase of gastric HCl secretion accounts for the majority of secretion control?

A

Gastric phase

38
Q

What drink can stimulate Gastric HCl secretion?

A

Coffee

39
Q

What can inhibit H+ secretion from parietal cells?

A

Omeprazole

40
Q

What can inhibit ECL cells from releasing Histamine (Histamine normally activates H+ secretion)?

A

Cimetidine

41
Q

What stimulation is the most important stimulus for pepsinogen secretion?

A

Vagus nerve

42
Q

H+ triggers local _____ reactions to stimulate chief cells to release _____

A

Cholinergic

Pepsinogen

43
Q

What converts more pepsinogen to pepsin?

A

Pepsin

44
Q

What does pepsin do?

A

Degrades food proteins into peptides

45
Q

Parietal cells also release intrinsic factor. What is it required for and where does this take place?

A

Vitamin B12 absorption in the distal ileum

46
Q

Pernicious anemia

A

Stomach does NOT produce enough intrinsic factor = decreased vitamin B12 absorption

47
Q

Common causes/disruptions of pernicious anemia/absorption of B12

A

Causes: atrophic gastritis or autoimmune
- loss of parietal cells or immune attacking IF/parietal
Disruptions: Gastrectomy or Gastric bypass

48
Q

What makes up the mucosal barrier that protects the gastric epithelium?

A

Mucous + HCO3-

49
Q

What will damage the mucosal barrier that normally protects the gastric epithelium?

A

Acid, pepsin, NSAIDs, helicobacter pylori, alcohol, bile, stress

50
Q

What is the purpose of the mucosal barrier in the stomach?

A

To protect the gastric epithelium from HCl and pepsin

51
Q

Zollinger - Ellison Syndrome

A

Large secretion of gastrin by duodenal/pancreatic tumors (gastrinomas)

52
Q

Zollinger - Ellison Syndrome causes an _____ in H+ and Gastrin secretion

A

INCREASE

53
Q

How do you diagnose a gastinoma/Zollinger - Ellison Syndrome?

A

Secretin stimulation test

54
Q

Under normal conditions, secretin will do what to gastrin release?

A

INHIBIT

55
Q

With gastrinomas, secretin will do what to gastrin release?

A

Cause an INCREASE = ACTIVATE

56
Q

What are the 2 types of peptic ulcers?

A

Gastric ulcer

Duodenal ulcer

57
Q

What is a main cause of a peptic ulcer?

A

Helicobacter pylori or NSAIDs

58
Q

A peptic ulcer results in the loss of?

A

Mucosal barrier loss with excessive acid and pepsin

59
Q

Gastric ulcer levels of H+ and gastrin

A

DECREASED H+ and increased gastrin

60
Q

Duodenal ulcer levels of H+ and gastrin

A

INCREASED H+ and gastrin

61
Q

Zollinger - Ellison syndrome levels of H+ and gastrin

A

MAJORLY INCREASED H+ and gastrin

62
Q

2 main things the pancreatic juice contains?

A

HCO3- aqueous solution

Enzymes

63
Q

What is the purpose of the pancreas secreting HCO3-?

A

Neutralize the H+ acid from stomach

64
Q

What do pancreatic enzymes do?

A

Digest food

65
Q

_____ activity increases pancreatic secretions

A

Parasympathetic

66
Q

______ activity decreases pancreatic secretions

A

Sympathetic

67
Q

What cells in the pancreatic duct synthesize and secrete enzymes?

A

Acinar cells

68
Q

What cells in the pancreatic duct secrete HCO3- solution?

A

Centroacinar and ductal cells

69
Q

Pancreatic acinar cells can secrete enzymes in their active or inactive form. What is an example of enzymes they secrete in the inactive form?

A

Proteases

70
Q

For a pancreatic ductal cell, it secretes and absorbs what?

A

Secretes HCO3- and absorbs H+

71
Q

Cystic fibrosis associated with a mutation of what?

A

CFTR Cl- channel in the pancreatic ductal cell

72
Q

Cystic fibrosis mutation of the pancreas leads to what?

A

Impaired HCO3- secretion from ductal cells

73
Q

What are the pancreatic secretion phases?

A

Cephalic - enzyme secretion
Gastric - enzyme secretion
Intestinal - enzyme AND HCO3- secretion

74
Q

What molecule activates the release of pancreatic enzymes?

A

CCK

75
Q

What molecule activates the secretion of HCO3- from the pancreas?

A

Secretin

GIGU (29 decks)

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