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gastric physiology Flashcards

1
Q

functions of stomach min 5

A 
Store and mix food
Dissolve and continue digestion
Regulate emptying into duodenum
Kill microbes
Secrete proteases 
Secrete intrinsic factor
Activate proteases
Lubrication
Mucosal protection
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2
Q

surface of gastric mucosa cells

A

mucous cells

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3
Q

where is gastric acid made

A

fundus and body of stomach

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4
Q

names of the three phases of gastric acid secretion

A

cephalic phase
gastric phase
duodenal phase

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5
Q

what to g cells make and their function

A

gastrin stimulate secretion of hcl and histamine

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6
Q

what does ach do in the cephalic phase - turning it on

A

acts on parietal cells to turn them on and triggers the release of gastrin and histamine

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7
Q

What do d cells make derek for

A

derek for somastin

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8
Q

gastric phase for the production of gastric acid ?

A 
g cells release gastrin 
acts on parietal cells
gastrin triggers release of histamine 
histamine acts directly on parietal cells
net goal= to increase acid production
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9
Q

function of proteins in the lumen

A

act as a buffer , mopping up H+ ionss causing ph to rise ,decreased secretion of somatostatin
more parietal cell activity due to lack of inhibition

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10
Q

how to stop gastric phase

A

low luminsl ph inhibits gastrin secretion via a negative feedback loop
inhibits histamine via gastrin
stimulates somastatin release inhibits parietal cell activity

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11
Q

turning off in the intestinal phase

A

Presence of chyme in duodenum stimulates entero endocrine cells to release cholecystokinin and secretin
Inhibit gastric acid secretion

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12
Q

which nerve innervate ach

A

VAGUS NERVE

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13
Q

what is a peptic ulcer

A

a breach in the musocal surface

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14
Q

causes of peptic ulcers

A

Helicobacter pylori infection
Drugs – NSAIDS
Chemical irritants – alcohol, bile salts, ? Dietary factors
Gastrinoma

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15
Q

treatment for peptic ulcers

A

tablets for one week

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16
Q

how does gastric mucosa defend itself

A

alkaline mucus
Tight junctions between epithelial cells
Replacement of damaged cells
Feedback loops

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17
Q

what does Helocobacter pylori do to cause peptic ulcer and treatment

A

Secretes urease , split urea into co2 and ammonia
Treatment - proton pump inhibitor to lower on
Followed by antibiotics

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18
Q

how do NSAID’s work to cause peptic ulcer

A

Inhibit cox-1
Reduced production of prostaglandin
More mucosal injury

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19
Q

how do bile salts cause peptic ulcer

A

Duodeno-gastric reflux
Regurgitated bile strips away mucus layer
Reduced mucosal defence

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20
Q

what cells produce pepsinogen

A

chief cells

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21
Q

what enzyme does the stomach produce

A

NO ENZYME

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22
Q

protease activation

A

positive feedback loop
pepsinogen into pepsin via HCL.
Pepsin is very ph dependant

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23
Q

how does pepsin help in protein digestion

A

breaks down collagen into meat, helps shred meat into smaller pieces , greater surface area

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24
Q

peristalsis

A

peristalsis waves- contractions weak at fundus and cardia then towards pylorus they become stronger and then closes

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25
What do the interstitial cells of cajal do
Pacemaker cells Control the frequency of contractions 3 a minute
26
what happens if you overfill the duodenum
dumping syndrome, vommiting , cramps, diarrhoea
27
gastroparesis
delayed gastric emptying
28
effects of gastroparesis
nausea, anorexia, abdo pain, vomit undigested food
29
Gastric acid secretion step by step
H20 and co2 combine to produce carbonic acid catalysed by carbonic anhydrase Carbonic acid dissociates into h+ and bicarbonate ion H+ moves into stomach via action be transport HCO3- out the cell and swap with cl- H and cl to make hcl
30
How to increase gastric acid production 2 ways
1)Via ach released from the vagus nerve Direct stimulation of parietal cells Produced during gastric phase where intrinsic nerves detect distension stimulating ach 2)activation of g cells leads to gastric release Gastrin released and binds to CCK receptors on parietal cells which elevates calcium levels causing increased vesicular fusion.
31
How does pepsinogen get converted to pepsin
By hcl
32
functions of the colon
Absorption of water and electrolytes Production of vitamins Excretion of waste
33
start oof the bowel
ileocaecal valve/ junction
34
layers of the colonic wall
Mucosa Submucosa Muscularis propria Serosa
35
histology of colon
columnar epithelium , goblet cells
36
what is the gastro-colic- reflex
Stomach stretching and food in the jejunum leading to mass movement of the colon
37
How do we know we need a poo?
Rectum fills Reflex relaxation of internal anal sphincter Sampling reflex
38
To complete defaecation
External sphincter relaxes Puborectalis relaxes Rectum contracts Valsalva maneuver
39
What do enterochromaffin ecl cells secrete
Histamine
40
What do H2 receptors do
Histamine binds to them Causing increased gastric aid production in stomach
41
How many layers of muscle in the stomach
3
42
two functions of pancreas
Endocrine secretion Exocrine secretion Aqueous bicarbonate secretion Enzyme secretion
43
what does the enyzme cholecystokinin do
Gallbladder contraction Inhibition of gastric acid secretion Delays gastric emptying
44
where is the enzyme Cholecystokinin produced
I cells of duodenum & jejunum
45
How does secretin inhibit gastrin and reduce gastric acid production
Release of somastatin | Inhibits release of gastrin in the pyloric antrum
46
action of the enzyme gastrin
HCl secretion (parietal cells) enzyme release (acinar cells)
47
consequences of exocrine dysfunction
malnutrition, osteoporosis, increased cardiovascular morbidity,
48
protein digestion ?
Pepsin initiates in stomach. Trypsin & Chymotrypsin packaged into secretory vesicles as proenzymes; prevents auto digestion Enterokinase embedded in Smallintestine mucosa. Active trypsin activates chymo and trypsinogen
49
what is a mesentery
The mesentery attaches your intestines to the wall of your abdomen.
50
How to work out bmi
Weight / height 2
51
What is bmr
Basal metabolic rate | The amount of energy needed to stay alive at rest
52
What can increase your bmr
Being overweight Male Pregnancy Exercise
53
What can decrease your bmr
Increase in age Malnutrition Starving Hypothyroidism
54
How is gastric acid produced
Parietal cells have a proton pump that release protons in exchange for k , proton binds with cl in lumen Ecf cells release histamine which bind to h2 receptors on parietal cells for more proton release Gastrin also promoted hcl production
55
Layers of the stomach
Mucosa Submicosa Muscularis externa Serosa
56
What happens in the cephalic phase
Activated upon seeing , smelling food etc Stimulation via vagus nerve and ach Ecl cells secrete histamine , g cells also release gastrin
57
What happens in the gastric phase
Stomach distension Triggers gastrin release , activates histamine release Hcl continues to be secreted in response to distension and amino acids digested due to proteases
58
What happens in the intestinal phase
Duodenum initially enhances gastrin secretion but soon inhibits it Enterogastroc reflex, duodenum sends inhibitory impulses to the stomach
59
What is gastric motility mediated by
Acetylcholine , parasympathetic vagus nerve | Nitric oxide serotonin
60
What increases the strength of gastric contractions
Gastrin | Distension of stomach
61
What decreases the strength of gastric contractions
Duodenal distension Increase in duodenal fat Decrease in duodenal fat Increase sympathetic stimulation
62
Role of pepsinohgen
Pepsinogen as an inactivate Zymogen of Pepsin Activated by low ph Increase protein digestion Shreds meat
63
What is gastric motility
Peristaltic contraction
64
Difference between large and small intestine
Small Smaller No appendices Wall smooth ``` Large Larger Longitudinal muscle is not continuous Has appendices Sacculated ```

Gastrointestinal (8 decks)

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