Lecture 11: Stomach (Sanchez) Flashcards Preview

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Flashcards in Lecture 11: Stomach (Sanchez) Deck (46):
1

Why is it normal to have backflow into the stomach from the duodenum in horses?

They have a loose pylorus

2

Where do most gastric mucosa secretions occur?

fundic part of stomach

3

What is secreted from cardiac part of stomach?

mucuous, bicarb.

4

What is secreted from fundic part of stomach?

pepsin, lipase, somatostatin, histamine, HCl

5

What is secreted from pyloric part of stomach?

pepsin, lipase, somatostatin, gastrin

6

gastric glands can be comprised of many types of cells including:

mucus surface cells, mucus neck cells, enterochromaffin-like cells, parietal cells, chief cell, D cells

7

D cells produce:

somatostatin

8

ECL cells produce:

histamine

9

parietal cells produce:

HCl

10

chief cells produce:

pepsinogen, gastric lipase

11

G cells produce:

gastrin

12

Parietal cells have receptors for:

-Ach
-gastrin
-histamine (most important)

13

ECL cells have receptors for:

Ach, gastrin

14

Major mech. of secretion for parietal cells

via H/K ATPase. On the basolateral surface of the cell, Na/K, Na/H, and HCO3/Cl exchangers get K and Cl into the cell so K can be exchanged for H by H/K ATPase, ultimately allowing the free H and Cl to combine and form HCl.

15

What stimulates G cells?

Ach, amino acids in gastric lumen, gastric distension

16

What inhibits G cells?

somatostatin

17

What stimulates D cells?

acidic lumen (lower than pH 4)

18

T or F: horses are continuous acid secreters

T

19

Do ECL secretions (histamine) have a paracrine or endocrine effect?

paracrine

20

Do G cell secretions (gastrin) have a paracrine or endocrine effect?

endocrine

21

What stimulates ECL cells?

Ach, gastrin

22

What inhibits ECL cells?

somatostatin

23

Main stimulators of acid secretion

1) amino acids
2) protein
3) gastric distension
4) Helicobacter pylori bacteria

24

Main inhibitors of acid secretion

1) luminal acid
2) lower than pH 4 gastric pH

25

Where and under what conditions is pepsinogen converted to pepsin?

within gastric lumen if pH is lower than 4

26

What secretes pepsinogen?

chief cells

27

Is gastric lipase secreted in active or inactive form? What secretes it? What does it do?

active via chief cells. Hydrolyzes long chain fats, but is NOT essential to digestion/absorption of fats

28

Why is high bloodflow to the stomach important?

Digestion + High rate of turnover of gastric cells

29

prostaglandin upregulates:

bicarb/mucus secretion, mucosal blood flow

30

prostaglandin downregulates:

acid secretion

31

functional properties of mucins

-lubricate epithelial surfaces
-diffusion barrier
-bind bad things (i.e. bacteria)
-interact w/immune surveillance system

32

mucus/bicarbonate secretion stimulators

prostaglandin, CGRP, nitric oxide, bradykinin

33

mucus/bicarb. secretion inhibitors

NSAIDs, tachykinins

34

2 basic components of gastric smooth muscle activity

1) the slow wave
2) the action potential (spike) - causes actual contraction when combined with slow wave

35

what is the slow wave of gastric smooth m. activity?

recurring oscillation of the resting memb. potential (underlying electrical current of the muscle) that does not cause muscle contraction

36

fx of interstitial cells of Cajal (ICC)

located within network of pacemaker region and throughout entire GI tract to help control rate and coordination of movement of ingest through GI tract. They propagate the slow wave

37

Where do slow waves usually start?

the fundus of the stomach. Their amplitude and rate increases aborally (towards pylorus)

38

What is a terminal antral contraction?

a mixing contraction in the distal stomach against a closed pylorus. Aids in particle size breakdown

39

which empties out of stomach faster: liquids or solids?

liquids. They empty almost instantaneously

40

What is gastric receptive relaxation?

Relaxation of the stomach in preparation for consumption of a meal. As a bolus of food moves down the esophagus, lower esophageal sphincter and gastric fundus relax

41

What is gastric accomodation?

great ability of stomach to distend in response to a meal

42

What is gastric compliance?

ability of stomach to contract back down as a meal empties into the duodenum

43

Feedback inhibition of gastric motility is effected by 3 things

osmolality, caloric density (higher fat meals stay in stomach longer), and CCK

44

Compare and contrast the contents, density, and pH of the top vs. bottom of an equine stomach

top: fiber solids, low density, high pH
bottom: liquids, high density, low pH

45

Products of equine intragastric fermentation

lactate (from soluble CHO in low pH regions) and VFA (from insoluble CHO in high pH regions)

46

What part of equine GI tract is lactate at the highest lvl?

stomach, due to intragastric fermentation

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