Gastric, Pancreatic, and Intestinal Secretion Flashcards Preview

Physio U4 > Gastric, Pancreatic, and Intestinal Secretion > Flashcards

Flashcards in Gastric, Pancreatic, and Intestinal Secretion Deck (59)
Loading flashcards...
1

Pepsinogen Function

digest 10-20% of proteins into peptides

2

Pepsinogen as inactive proenzyme

pH <5 and autocatalyzes pepsinogen to pepsin

3

Optimal pH for pepsin activity

1.5-2

4

Factors that increase pepsinogen secretion

ACh, pH <3, Gastrin

5

Gastric Lipase Function

digests 15% triglycerides to 2-monoglyceride and 2FFA

6

Optimal pH for gastric lipase activity

3-8

7

Gastric lipase in infants

more important bc pancreatic lipase is not abundant

8

Factors that increase gastric lipase

ACh

9

Intrinsic Factor Function

Binds Vitamin B12 in duodenum and transporting it to ileum for absorption

10

Gastric mucosal barrier

mucin glycoproteins and water with trapped HCO3

11

Function of Gastric mucosal barrier

Protect mucosa from pepsin and H+, slow-back diffusion of H+ into enterocytes, Trap any luminal H+ and buffer with HCO3

12

Mucin Function

protect mucosa from pepsin, HCl, bacterial invasion, and physical damage, and lubricate food

13

Mucin secretion

from surface mucus cells and mucus neck cells via exocytosis (continuous) and cell exfoliation (cells replaced every 3 days)

14

Factors that increase mucin secretion

ACh, gastrin, and prostaglandins

15

Bicarbonate Secretion Function

buffer H+ that enters the gastric mucosal barrier

16

Bicarbonate Secretion

from surface mucus cells and mucus neck cells using HCO-Cl antiporter (CA generates HCO)

17

Factors that increase Bicarbonate Secretion

prostaglandins, H+ in lumen, ACh

18

ALL surface mucus cells and mucus neck cells secrete

Mucus and HCO

19

What is the pH at the apical cell surface (beneath the gastric mucosal barrier)?

7

20

Prostaglandins are cytoprotective, function is

Decrease H+ secretion, increase mucus and HCO secretion, and increase gastric blood flow

21

Pepsin is inactive within the mucosal barrier, Why? and why is this important

mucosal barrier has a pH of 7 (pepsin inactive at 7), important to avoid digesting stomach lining

22

Peptic Ulcer Disease

loss of mucosal surface, imbalance of gastric acid and pepsin, and protective elements (mucus, HCO, and prostaglandins)

23

Causes of PUD

H. pylori, NSAID use

24

Zollinger-Ellison Syndrome

gastrinoma producing elevated levels of gastrin, causes PUD

25

H. pylori infection

adheres to and colonizes gastric-type epithelium causing an inflammatory and bacterial response altering cell characteristics

26

Chronic H. Pylori + pangastritis

results in hypochlorhydia, high levels of gastrin normal level of H+ (cytokines inhibit H+ secretion)

27

Chronic H. Pylori + antral gastritis

results in hyperchlorhydia, high levels of gastrin AND H+, due to somatostatin dysfunction

28

H. pylori produces urease

splits urea into ammonia CO2 and HCO3, increasing pH and allowing survival of bacteria and weakening the mucosal barrier

29

NSAIDs and peptic ulcers

COX inhibitor prevents synthesis of prostaglandins, allowing increased H+ secretion, decreased mucus and HCO secretion, and decreased gastric blood flow

30

COX2

does not effect GI, but will reduce swelling and pain