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Body Systems > The stomach > Flashcards

The stomach Flashcards

1
Q

describe the anatomy of the stomach

A

check home screen folder

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2
Q

what is the role in secretion and motility of the lower oesophagus and cardia of the stomach

A

secrete mucus and HCO3-
prevention of reflux
entry of food
regulation of belching

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3
Q

what is the role in secretion and motility of the fungus and body of the stomach

A

secrete - H+, intrinsic factor mucus, HCO3-, pepsinogens, lipase
acts as reservoir, tonic force during emptying

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4
Q

what is the role in secretion and ruction of the antrum and pylorus

A

secrete mucus

role in mixing grinding sieving and regulation of emptying

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5
Q

which part of the stomach accepts and holds food

A

fundus and body

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6
Q

what is the function of the antrum and pylorus in he stomach

A

antrum - churning and grinding food as well as involved in emptying
pylorus is involved in emptying

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7
Q

what does accommodation of the stomach require

A

vago-vagal reflex

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8
Q

what does accommodation of the stomach depend on and what does it involve

A

depends on stretch receptors signalling the vagus which act on the enteric system resulting in relaxation of the stomach and dilation of the fungus and body

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9
Q

what size particles cannot pass through the pyloric sphincter

A

larger than 1-2 mm

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10
Q

when the duodenum senses delivery of acid, amino acid and lips what happens

A

duodenum secretes hormones such as CCK, secretin and GIP which decrease gastric motility

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11
Q

describe what happens in the cephalic reflex

A

sight, smell, taste or thought of food
sight/thought - cerebral cortex which triggers hypothalamus and medulla (which are directly stimulated by taste and smell)
stimulated vagus nerve - stimulates stomach secretory activity

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12
Q

how does depression affect the cephalic reflex

A

loss of appetite such as in depression affects cerebral cortex and lack of stimulation of para symp centre which inhibits stomach activity

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13
Q

what happens in the stimulatory gastric phase

A

stomach distension activates stretch receptors which targets local reflexes and vasovagal reflex - medulla and vagus nerve which all stimulate secretory activity
food chemicals and rise in ph triggers G cells to secrete more gastrin into blood which means more secretory activity

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14
Q

what decreases stomach secretory activity in the gastric phase

A

excessive acidity - decrease in gastrin secretion

emotional distress increases sympathetic nervous system

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15
Q

what stimulates secretory stomach activity in the intestinal phase

A

presence of low ph and partially digested food in the duodenum - intestinal gastrin release into blood and more secretory stomach activity

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16
Q

what actions in the intestinal phase inhibit stomach secretory activity

A

distension of duodenum with presence of fatty, acidic, hypertonic, chyme or irritants
these all lead to local reflexes, pyloric sphincter and vagal nuclei in medulla which stimulate enterogastric reflex and inhibit stomach secretion

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17
Q

describe the anatomy of gastric pits and glands

A

check home screen folder for diagram

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18
Q

what do mucus cells secrete

A

mucus and HCO3-

19
Q

what do parietal cells do and what are they also called

where are they primarily found

A

oxyntic - secrete HCL and intrinsic factor

found in the fungus and body

20
Q

what do chief cells do

A

also called peptic cells and they secrete pepsinogen

21
Q

what are the two types of gastrin and what is it

A

peptide hormone released from G cells
G17 - main from secreted from antrum
G34 - C-terminal 17 are the same as G17 - main form secreted from the duodenum

22
Q

what is gastrin homologous with

A

CCK-PZ and can share receptors

23
Q

what simulate release of gastrin

A

lumen protein / amino acids

para symp input mediated by gastrin releasing peptide and interneurons

24
Q

what inhibits gastrin release

A

lumen H+ via negative feedback

25
Q

what are the main actions of gastrin

A

stimulate acid secretion and promote mucosal growth

26
Q

what are the two types of somatostatin

A

14 and 28 - 28 most common

27
Q

where is somatostatin released

A

D cells in stomach, duodenum and pancreas

28
Q

how does somatostatin reach its target

A

mainly paracrine and endocrine

29
Q

what stimulates release of somatostatin - what inhibits it

A

lumen H+ and inhabited by ACh

30
Q

what is the role of somatostatin

A

acts on G cells to inhibit gastrin release and also CCk and secretin

31
Q

what is the anatomical difference between raton and active parietal (oxyntic)

A

resting have tubulovesicles

active have canaliculus

32
Q

what protects the epithelium

A

bicarbonate and mucus secretion

33
Q

what is intrinsic factor, where is it released and what do it do

A

55 kDa glycoprotein
rebased from parietal cells in stomach
binds to cobalamin (vit B12) but not until it reaches the small intestine
essential for cobalamin uptake in the ileum

34
Q

what mediates effect of gastrin

A

CCK-a receptors

35
Q

what are pepsins

A

family of proteases secreted from the chief and mucus cells

36
Q

when are pepsins released

A

in response to ACh H+, minor effects of secretin, cck and gastrin

37
Q

what are pepsins secreted as and how are they activated

A

secreted as pro hormones (pepsinogens)
cleaved spontaneously at low pH less than 5 and quickly less than 3
cleaved by pepsin (autolysis)

38
Q

what is a pepsin(s)

A

endoproteases - they are cut within the peptide chain rather than going for the terminal amino acid
optimum pH 2-3
denature above 5-7

39
Q

what is and what is the role of gastric lipase

A

involve din initial digestion of triglycerides

cleave the outer fatty acids off triglycerides leaving diacyl glycerol

40
Q

what is the optimum ph for gastric lipase

A

4 - stable in the stomach but denatured by pancreatic proteases

41
Q

what does ptyalin a amylase do and is its optimum ph

A

initial digestion of polysaccharides

optimum ph of 7 and denatured at ph 4

42
Q

what are the causes of vomiting

A

vagal afferents in response to irritants
psychogenic (pain, revulsion)
motion sickness (labyrinthine disorders)
drugs or toxins
pregnancy

43
Q

what is the central role of vomiting

A

area postrema = chemotrigger zone

44
Q

what are the consequences of vomiting

A

salivation, sweating, hyper ventilation
retrograde peristalsis
retching (involuntary contractions of diaphragm and abdominal wall
displacement of the cardia in the thorax

Body Systems (77 decks)

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