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Flashcards in GI Module 2 Deck (97)
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1

After initial digestive processes the stomach propels food into the ________.

Duodenum

2

What is the term for stomach distention that stimulates vagal mechanoreceptors which reflexively stimulates vagal VIP release to relax smooth muscle of stomach wall?

Vaso-vagal reflex

3

What is the stimulus for gastric emptying?

Parasympathetic activity

4

Explain the sequence of gastric emptying (2 main steps)

1. Retropulsion-contractions push food back towards body of stomach.
2. Last wave "forces" pyloric sphincter to open and allow sm. amount of chyme into duodenum

5

Pylorus opens a ______ amount.

small (1-2cm)

6

What passes fastest to the duodenum

liquids

7

What solids pass fastest to duodenum

Proteins empty faster than fats

8

What is average time to empty 50% of stomach?

50% after 2-3 hours

9

What is average total time to completely empty stomach?

4-5 hours total emptying

10

What factors can increase the rate of gastric emptying?

Larger food volume increase rate

11

What factors decrease rate of gastric emptying?

Hyper/hypotonic fluid-status of fluid concentration
Fatty Foods-take a long time to break down
Acidic food-neutralization takes time

12

What type of feedback loop are the factors that decrease or increase gastric emptying?

negative

13

T/F increased blood glucose will increase gastric motility and gastric emptying.

F!!! Increased blood glucose does increase gastric motility but DOES NOT increase gastric emptying.

14

What are the major secretions of the stomach? (5)

Mucus
Acid
Pepsinogen
Hormones
Intrinsic factor

15

What are the hormones secreted from stomach? (5)

Gastrin
Histamine
Somatostatin
Serotonin
Ghrelin

16

What is the function of mucus in the stomach?

Protects mucosal layer from acid and pepsinogen

17

What does the mucus contain that works to neutralize the H+?

High levels of bicarbonate

18

What is the pH of the mucous layer of the stomach?

7.0 (neutral)

19

What pH is the acid of the stomach?

1.5 (acidic)

20

What stimulates mucus secretion in the stomach?

Prostaglandins
Nitric Oxide

21

What can disrupt the mucus barrier in the stomach (and cause ulceration/inflammation).

1. Drugs: Aspirin, NSAIDS, ETOH
2. Bile salts - regurgitant from SI
3. H. pylori

22

What is the function of acid in the stomach?

Dissolve food
Inactivation of digested bacteria/microorganisms
Convert pepsinogen to pepsin

23

Where is acid secreted from in the stomach?

Parietal cells

24

Acid formation/secretions occurs in "exchange" for ______?

Bicarbonate

25

Increased gastric acid secretion will increase ______ entering plasma?

Bicarbonate

26

Acid secretion is stimulated by what?

Ach (acetylcholine)-via vagus nerve (parasymp)
Gastrin
Histamine

27

What would occur if only one of the three mechanisms for acid secretion occurred?

Only a small amount of acid would be produced. All 3 Ach, gastrin, and histamine work synergistically to produce a large amount of acid.

28

What works to inhibit acid secretion (5)

1 Somatastatin (universal GI inhibitor)
2. Prostaglandin E2 (PGE2)
3. Gastric Inhibitory Peptide (GIP)
4. Secretin
5. Glucagon

29

What are the 3 gastric phases of acid secretion?

1. Cephalic
2. Gastric
3. Intestinal

30

What stimulates the Cephalic Phase?

ACh CNS stimulation-sight, smell, taste, thought of food.
"The food channel effect"