20. GI secretory products Flashcards Preview

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Flashcards in 20. GI secretory products Deck (27):
1

Intrinsic factor - source

Parietal cells
(stomach)

2

Intrinsic factor - action

Vitamin B12–binding
protein (required for B12
uptake in terminal ileum)

3

Autoimmune destruction
of parietal cells -->

chronic
gastritis and pernicious
anemia.

4

Gastric acid -SOURCE

Parietal cells
(stomach)

5

Gastric acid - ACTION

dECREASED stomach pH

6

Gastric acid - REGULATION

INCREASED by histamine,
ACh, gastrin
DECREASED by somatostatin,
GIP,
prostaglandin,
secretin

7

Pepsin -SOURCE

Chief cells
(stomach)

8

Pepsin - ACTION

Protein digestion

9

Pepsin - REGULATION

increased by vagal
stimulation,
local acid

10

Pepsinogen (inactive) is
converted to

pepsin (active) in
the presence of H+.

11

Bicarbonate trapped in

Trapped in mucus that covers
the gastric epithelium.

12

Bicarbonate -SOURCE

Mucosal cells
(stomach,
duodenum,
salivary glands,
pancreas) and
Brunner glands
(duodenum)

13

Bicarbonate - ACTION

Neutralizes acid

14

Bicarbonate -REGULATION

INCREASED by pancreatic
and biliary
secretion with
secretin

15

• In pernicious anemia, destruction of gastric ____ cells leads to deficiency of ____ required for vitamin B12 uptake in the ____.


Parietal; intrinsic factor; terminal ileum

16

• A patient has chronic abdominal pain and numerous peptic ulcers refractory to proton pump inhibitors. What tumor should be suspected?

Gastrinoma, which is a gastrin-secreting tumor that results in high levels of acid secretion

17

• Describe how pepsin is activated.

It is activated by vagal stimulation of increased acid output, which cleaves inactive pepsinogen to active pepsin

18

• What is the primary role of pepsin? What cells secrete it, and where are these cells found?

Functions in protein digestion; secreted by the gastric chief cells

19

• Bicarbonate is secreted by ____ cells and ____ glands; its function is to ____ acid.

Mucosal; Brunner; neutralize

20

• A patient with a gastrinoma can be expected to also have excessive activation of which pro-enzyme?

Pepsinogen (activated by acid, the release of which is stimulated by gastrin)

21

• Produced by these cells found in this organ, pepsinogen becomes pepsin when there is a high acid content in the stomach.

Chief cells of the stomach

22

• Increased levels of what three molecules cause parietal cells to release gastric acid?

Acetylcholine, histamine, and gastrin

23

• Decreased levels of which hormones will cause parietal cells to secrete gastric acid?

Somatostatin, GIP, prostaglandin, secretin

24

• Increased secretin levels increase the secretion of this molecule, whose main purpose is to neutralize acid.

Bicarbonate

25

• Where is bicarbonate typically trapped in the GI system?

Bicarbonate is trapped in the mucus that covers the gastric epithelium

26

• A patient has vitamin B12 deficiency. What part of the GI system could be damaged, impacting vitamin B12 levels?

Parietal cells of the stomach or the terminal ileum (the latter is where vitamin B12 is absorbed as a complex with intrinsic factor)

27

• Where are bicarbonate-secreting mucous glands found? What about bicarbonate-secreting Brunner glands?

Stomach, duodenum, salivary glands, pancreas; duodenum

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