physiology of the GI tract Flashcards

1
Q

what makes up the upper GI tract?

A
oral cavity 
salivary glands 
pharynx 
oesophagus 
stomach 
pancreas
liver 
gall bladder
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2
Q

what makes up the lower GI tract?

A

small and large intestine

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3
Q

what are the major sites of absorption?

A

stomach
small intestine
large intestine

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4
Q

what is absorbed in the stomach?

A

alcohol and water

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5
Q

what is absorbed in the small intestine?

A
minerals 
glucose 
amino acids 
fats 
vitamins 
water 
alcohol 
bile salts
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6
Q

what is absorbed in the large intestine?

A

sodium
potassium
some fatty acids, gases and water

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7
Q

what is the function of the oral cavity?

A

mastication

mixes food with saliva

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8
Q

what are the names of the three pairs of salivary glands?

A

parotid
submandibular
sublingual

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9
Q

what cells are present in the salivary glands and what do they secrete?

A

mucus cells secrete mucus
serous cells secrete thin fluid rich in amylase
mixed acinus has both

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10
Q

what is the function of saliva?

A
moisten 
begin starch and fat digestion 
cleanse teeth 
inhibit bacteria 
bind food into bolus
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11
Q

what is the pharynx and what is its function?

A

air filled cavity
transports food from the mouth to the stomach
constrictor muscles in pharynx move bolus into oesophagus

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12
Q

what is the function of the stomach?

A
stores food 
minimizes ingestion of bacteria 
reduces food to chyme 
regulates the rate that contents empty into the small intestine 
secretes intrinsic factor
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13
Q

what cells line the gastric glands?

A
goblet 
stem cells 
parietal cells 
chief 
enteroendocrine
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14
Q

what do goblet cells secrete in the gastric glands?

A

mucus

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15
Q

what is the function of parietal cells in the gastric glands?

A

secrete HCl acid and intrinsic factor

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16
Q

what is the function of chief cells in the gastric glands?

A

secrete pepsinogen

and chymosin and lipase in infancy

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17
Q

what is the function of enteroendocrine cells in the gastric glands?

A

G cells secrete gastrin
D cells secrete somatostatin
enterochromaffin- like cells secrete histamine

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18
Q

what are the main components of gastric juice?

A

hydrochloric acid
mucus
enzymes: pepsinogens, gastric lipase
intrinsic factor

19
Q

what stimulates gastric acid production?

A

cephalic phase and gastric phase

gastrin, acetylcholine and histamine

20
Q

what inhibits gastric acid production?

A

intestinal phase

somatostatin

21
Q

what is the function of gastric acid?

A

activates pepsin and lingual lipase
denatures proteins
breaks up connective tissues and plant cell walls
converts ingested ferric ions to ferrous ions
destroys ingested bacteria and pathogens

22
Q

what enzymes does the pancreas produce?

A
trypsin 
chymotrypsin 
carboxypeptidase 
pancreatic amylase 
lipases
23
Q

what is the hepatopancreatic ampulla?

A

where the common bile duct and pancreatic duct meet

24
Q

what is the function of the liver?

A

sythesises and stores bile

25
Q

what is the function of bile salts?

A

emulsifies dietary lipids, rendering them accessible to pancreatic lipases
facilitates the absorption of fat-soluble vitamins

26
Q

what are the three sections of the small intestine?

A

duodenum
jejunum
ileum

27
Q

what are peyer patches in the small intestine?

A

populations of lymphocytes

28
Q

what cells are present in intestinal crypts?

A

absorptive cells
goblet cells
rapidly dividing cells
paneth cells

29
Q

what is secreted by the small intestine?

A

mucus
water
hormones

30
Q

what are scretagogues?

A

hormones controlling secretions

31
Q

how is gastric acid produced?

A

H+ and HCO3- produced from CO2 and H20 by carbonic anhydrase
H+ secreted into stomach lumen by a H+/K+ ATPase
HC03- exchanged for Cl-
Cl- pumped out and joins with H+ forming HCl

32
Q

where is gastrin produced?

A

in the antrum of the stomach by epithelial endocrine cells

33
Q

what is the stimulus for gastrin release?

A

amino acids and peptides in stomach

34
Q

what effect does gastrin have in the stomach?

A

stimulates HCl secretion

35
Q

where is cholecystokinin produced?

A

in the small intestine by intestinal endocrine cells

36
Q

what is the stimulus for cholecystokinin release?

A

amino acids, peptides and fatty acids in the small intestine

37
Q

what effect does cholecystokinin have in the stomach?

A

inhibits acid secretion

38
Q

where is secretin produced?

A

in the small intestine by intestinal endocrine cells

39
Q

what is the stimulus for secretin release?

A

acid in the small intestine

40
Q

what effect does secretin have in the stomach and pancreas?

A

inhibits acid secretion in the stomach

stimulates bicarbonate secretion in the pancreas

41
Q

where is GIP produced?

A

in the small intestine by intestinal endocrine cells

42
Q

what is the stimulus for GIP release?

A

glucose and fat in the small intestine

43
Q

what is the effect of GIP in the pancreas?

A

stimulates beta cells to secrete insulin