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STRUC+FUNC 2 (vet) > Gastric Function > Flashcards

Gastric Function Flashcards

1
Q

what are the three main tasks of the stomach?

A

temporary food store (most important)
some degradation of protein and starch - smaller surface area
Hydrochloric acid kills bacteria in food - and enzyme (Pepsin) activation

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2
Q

most important stomach function?

A

temporary food store

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3
Q

band of muscle down the pipe of the oesophagus?

A

sphincter

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4
Q

what is almost absent in horses and really small in other species apart from pigs where it is large?

A

cardia

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5
Q

sphincters are?

A

muscular bands

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6
Q

when the stomach is empty, what is maintained?

A

contraction is maintained = tonic contraction

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7
Q

when an animal eats, what happens to the stomach?

A

the muscles relax = receptive relaxation

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8
Q

what is receptive relaxation regulated by?

A

via vagal fibres

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9
Q

what does relaxation allow for?

A

it allows for increase in stomach content without the increase in pressure - this aids the ‘food storage’ function of the stomach

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10
Q

what area of the stomach is the distal stomach referring to?

A

mainly to pyloric area

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11
Q

what does the arrival of waves of depolarisation result in?

A

large parts of the pylorus wall contracting simultaneously, increasing luminal pressure and forcing chyme through the partially open sphincter

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12
Q

type of epithelial on oesophageal sphincter?

A

stratified squamous

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13
Q

why does more active digestion occur in the distal stomach?

A

due to stronger peristaltic contractions

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14
Q

why are larger particles held back in the stomach?

A

so they can be broken down further

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15
Q

what are the 4 types of cells in the crypts/pits of the stomach?

A

mucin producing
parietal
chief
endocrine

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16
Q

what do the mucin producing cells secrete?

A

mucin

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17
Q

‘ogen’

A

inactive precursors

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18
Q

what do parietal cells secrete?

A

HCl and intrinsic factor

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19
Q

what do chief cells secrete?

A

pepsinogen

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20
Q

what do endocrine cells secrete?

A

G cells secrtee gastrin or ECL cells which secrtee histamine)

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21
Q

where is most gastric juice produced?

A

in the glands of fundus and corpus

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22
Q

what do the glands in the cardia region secrete?

A

only mucus - protective role

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23
Q

what do gastric juices consist mainly of?

A

HCl and pepsinogen

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24
Q

what mainly secretes HCl?

A

mainly from parietal cells

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25
Q

what does HCl do to tissue/muscle?

A

degrades connective tissue and muscle

26
Q

what does HCl do to microorganisms?

A

kills them

27
Q

carbonic anhydrase>?

A

enzyme for conversion of co2 and h2o to h2co3

28
Q

after being fed, pH?

A

increases

29
Q

pepsinogen stored and synthesised by?

A

chief cells

30
Q

what is pepsinogen?

A

the inactive form of pepsin

31
Q

what does pepsin do?

A

degrades feed proteins to peptides

32
Q

type of catalysis that pepsinogen is used in?

A

autocatalysis role of pepsin

33
Q

what three substances exert stimulatory effects in order to regulate gastric secretion?

A

ACh
gastrin
histamine

34
Q

Where is HCl mainly secreted from?

A

mainly from parietal cells

35
Q

for the regulation of gastric secretion, what three substances exert stimulatory effects?

A

ACh
Gastrin
Histamine

36
Q

signals to nervous system good for?

A

stops overfeeding and over secretion

37
Q

what happens during anticipatory part of secretion?

A

saliva and vagal nerve stimulation

38
Q

summary of secretion:

A

saliva + vagal nerve stimu
vagal stimu of chief cells - pepsinogen
vagal stimulation of parietal cells - HCl
stimulation of G cells to release gastrin (+ve feedback on parietal cells and ECL cells)
ECL cell stimulation (histamine) drivers further HCl secretion

39
Q

point of mechanoreceptors in stomach?

A

they detect the stomach wall stretching - drives secretion until feed is complete

40
Q

how is secretion inhibited?

A

signals from duodenum
if pH falls too low - somatostatin release (blocks gastrin release)
At start of meal (b4 food reaches stomach) HCl secretion is low but H+ conc high
This blocks further acid secretion
When animal eats, stomach supplied with buffer (proteins) so [H+] decreased + gastrin is released

41
Q

what happens when the animal is going to eat?

A

the stomach is supplied with buffer (proteins), [H+] decreases and gastrin is released

42
Q

what happens if pH falls too low?

A

somatostatin release (blocks gastrin release)

43
Q

level of HCl before food reaches the stomach (at the start of the meal)?

A

HCl secretion is low but [H+] is high

44
Q

what does low HCl and high [H+] do?

A

it blocks further acid secretion

45
Q

where is recently swallowed food found?

A

in the proximal area of the stomach

46
Q

contraction in the proximal area of stomach - strength, meaning?

A

the contractions are weak so food layers in the order it was eaten - enables enzymes to act before becoming deactivated e.g. amylase for starch

47
Q

describe the food found in the distal portion of the stomach?

A

it is well mixed with HCl and pepsin

48
Q

gut’s own nervous system?

A

enteric nervous system

49
Q

factors affecting gastric emptying?

A

expansion of the stomach wall
gastrin
Distension of duodenum
high fat and protein concentrations (requires slower digestion)
reduced pH
important mediators

50
Q

what does GIP do?

A

mediates changes in gastric emptying

51
Q

what does secretin do?

A

stimulated by acidity, increases HCO3 production by pancreas

52
Q

what do the epithelial glands of the abomasum produce?

A

producing pepsinogen and HCl

53
Q

what do young ruminants produce from the abomasum? what is this used for?

A

they also produce rennin
helps with digestion of milk

54
Q

because the absomasum is not a storage organ - what does it do?

A

it receives a continuous flow of ruimen content

55
Q

pH of the absomasum?

A

low pH

56
Q

how is emptying regulated in the abomasum?

A

the same way as the stomach

57
Q

what does HCl do for the stomach?

A

degrades connective tissue and muscle
and kills microorganisms

58
Q

what does HCl do to pepsinogen?

A

it transforms pepsinogen (precursor) to pepsin (active enzyme)

59
Q

How is HCl produced?

A

Produced by: H/K ATP-ase pump which provides the H+
and the HCO3-/Cl- pump which provides Cl-

60
Q

How is HCl produced after a meal?

A

Production of HCl after a meal requires simultaneous stimulation of parietal cells by all three substances (ACh, gastrin, histamine)
Gastrin is released into the blood to stimulate secretion of HCl, pepsinogen and to promote gastric motility
Histamine acts as a paracrine hormone, stimulating HCl secretion
Vagal reflexed are stimulated by stomach expansion

61
Q
A

STRUC+FUNC 2 (vet) (29 decks)

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