Lecture 11: Stomach (Sanchez) Flashcards Preview

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

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

A

They have a loose pylorus

2
Q

Where do most gastric mucosa secretions occur?

A

fundic part of stomach

3
Q

What is secreted from cardiac part of stomach?

A

mucuous, bicarb.

4
Q

What is secreted from fundic part of stomach?

A

pepsin, lipase, somatostatin, histamine, HCl

5
Q

What is secreted from pyloric part of stomach?

A

pepsin, lipase, somatostatin, gastrin

6
Q

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

A

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

7
Q

D cells produce:

A

somatostatin

8
Q

ECL cells produce:

A

histamine

9
Q

parietal cells produce:

A

HCl

10
Q

chief cells produce:

A

pepsinogen, gastric lipase

11
Q

G cells produce:

A

gastrin

12
Q

Parietal cells have receptors for:

A
  • Ach
  • gastrin
  • histamine (most important)
13
Q

ECL cells have receptors for:

A

Ach, gastrin

14
Q

Major mech. of secretion for parietal cells

A

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
Q

What stimulates G cells?

A

Ach, amino acids in gastric lumen, gastric distension

16
Q

What inhibits G cells?

A

somatostatin

17
Q

What stimulates D cells?

A

acidic lumen (lower than pH 4)

18
Q

T or F: horses are continuous acid secreters

A

T

19
Q

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

A

paracrine

20
Q

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

A

endocrine

21
Q

What stimulates ECL cells?

A

Ach, gastrin

22
Q

What inhibits ECL cells?

A

somatostatin

23
Q

Main stimulators of acid secretion

A

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

24
Q

Main inhibitors of acid secretion

A

1) luminal acid

2) lower than pH 4 gastric pH

25
Q

Where and under what conditions is pepsinogen converted to pepsin?

A

within gastric lumen if pH is lower than 4

26
Q

What secretes pepsinogen?

A

chief cells

27
Q

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

A

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

28
Q

Why is high bloodflow to the stomach important?

A

Digestion + High rate of turnover of gastric cells

29
Q

prostaglandin upregulates:

A

bicarb/mucus secretion, mucosal blood flow

30
Q

prostaglandin downregulates:

A

acid secretion

31
Q

functional properties of mucins

A
  • lubricate epithelial surfaces
  • diffusion barrier
  • bind bad things (i.e. bacteria)
  • interact w/immune surveillance system
32
Q

mucus/bicarbonate secretion stimulators

A

prostaglandin, CGRP, nitric oxide, bradykinin

33
Q

mucus/bicarb. secretion inhibitors

A

NSAIDs, tachykinins

34
Q

2 basic components of gastric smooth muscle activity

A

1) the slow wave

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

35
Q

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

A

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

36
Q

fx of interstitial cells of Cajal (ICC)

A

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
Q

Where do slow waves usually start?

A

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

38
Q

What is a terminal antral contraction?

A

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

39
Q

which empties out of stomach faster: liquids or solids?

A

liquids. They empty almost instantaneously

40
Q

What is gastric receptive relaxation?

A

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
Q

What is gastric accomodation?

A

great ability of stomach to distend in response to a meal

42
Q

What is gastric compliance?

A

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

43
Q

Feedback inhibition of gastric motility is effected by 3 things

A

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

44
Q

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

A

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

45
Q

Products of equine intragastric fermentation

A

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

46
Q

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

A

stomach, due to intragastric fermentation

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