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2.3.5. Gastrointestinal System > Function and Pathology of the Stomach > Flashcards

Function and Pathology of the Stomach Flashcards

1
Q

Outline the basic anatomy of the stomach

A

Greater/lesser curve

Rugae

Caridia, fundus, body, antrum

Lower oesophageal sphincter

Pyloric sphincter

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2
Q

What lines the stomach?

A

Columnar = secretion

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3
Q

The holes that make up the surface of the stomach are called?

A

Gastric pits

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4
Q

What cell types are present in gastric pits?

A

Mucous cells

Parietal cells

Chief cells

G cells

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5
Q

Explain how the movements in the stomach differ

A

Upper = sustained contractions, creates basal tone

Lower = strong peristalsis mixes stomach contents

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6
Q

How does the stomach help the fact we consume food faster then we can digest it?

A

Storage site

Relaxation of stomach allows food to enter without raising intra-gastric pressure too much

Prevents reflux

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7
Q

What is the purpose of the acidic environment in the stomach?

A

Helps unravel proteins

Activates proteases (pepsinogen to pepsin)

Disinfect stomach contents

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8
Q

What cells are present in the stomach and what do they secrete?

A

Parietal cell = HCL, intrinsic factor

G cells = gastrin

Enterochromaffin like cells = histamine

Chief cells = pepsinogen

D cells = somatostatin

Mucous cells = mucus

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9
Q

What stimulates parietal cells to prod HCL?

A

Gastrin

Histamin

ACh

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10
Q

What stimulates gastrin secretion?

A

Peptides/AA in stomach lumen

ACh

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11
Q

Outline how HCL production is inhibited?

A

Food leaves stomach = no buffer present = lowers pH = activates D cells = release somatostatin = inhib G cells = no gastrin = no stim of parietal cells to release HCL

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12
Q

What are the phases of digestion?

A

Cephalic (30% of total HCL) = oral, voluntary, amylase, mixing, lubricating

Gastric (60% of total HCL) = pepsin, AA stim G cells, food acts as buffer

Intestinal (10% of total HCL) = bile, chyme stim gastrin/CCK/secretin

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13
Q

How does the stomach protect itself?

A

High turnover of epithelial cells

Prostaglandins = maintain blood flow supplying ep with nutrients

Mucus and HCO3

Released by = surface mucus cells, neck cells in gastric glands

Forms thick alkaline viscous layer on epithelium = higher pH

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14
Q

What things can breach stomach defences?

A

Alcohol

Helicobacter pylori

NSAIDs

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15
Q

Outline GERD

A

Reflux of stomach contents into the oesophagus

Symptoms = heartburn, cough, sort throat, dysphagia

Causes = LOS problems, delayed gastric emptying, obesity

Can result in Barretts oesophagus

Treatment = lifestyle modifications, antacids, PPIs

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16
Q

Describe gastritis

A

Acute mucosal inflam = heavy use of NSAIDs, alcohol, chemo

Chronic mucosal inflam = H-pylori, autoimmune

17
Q

What is peptic ulcer disease?

A

Defects extending through muscularis mucosa

Commonly affects lesser curve

Cause = stomach acid, H-pylori, NSAIDs

Symptoms = epigastric pain, bleeding, anaemia, weight loss

Treat = eradicate H-pylori, stop NSAIDs, PPIs, H2 blockers

18
Q

What is helicobacter-pylori?

A

Bacteria - spirochete

Spread = oral-oral, faecal-oral

Prod urease = converse urea to ammonium = increases pH

Lives in mucus layer

Releases cytotoxins = direct ep injury

Promotes inflam response

19
Q

What is zollinger-ellison disease?

A

Tumours in the pancreas/duodenum = large amounts of gastrin = stomach prod too much HCL

20
Q

How does the stomach physically disrupt food?

A

muscular contractions of the antrum

21
Q

What is receptive relaxation?

A

relaxation of the upper portion of the stomach to maintain a steady pressure within the stomach

22
Q

How is chyme best described as it leaves the stomach?

A

hypertonic and acidic

23
Q

What parietal cell receptor can be blocked to reduce stomach acid prod?

A

H2

24
Q

Why do NSAIDs increase the risk of peptic ulceration?

A

reduce gastric prostaglandin secretion = reduces gastric mucosal blood flow = cant maintain health cell turnover and repair mechanisms

reduce the effectiveness of the mucosal barrier

25
Q

How does H.pylori survive the acidic conditions in the stomach?

A

produce urease = urea to ammonia = raised pH

26
Q

What causes the alkaline tide following a meal?

A

movement of HCO3- across the basolateral mem

27
Q

what type of chronic gastritis can lead to megaloblastic anaemia?

A

autoimmune

attacks the parietal cells = essential for secreting intrinsic factor = which is essential for absorbing vit B12 = B12 def result in megaloblastic anaemia

2.3.5. Gastrointestinal System (17 decks)

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