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(LUSUMA) Gastro-intestinal System > S5) Function and Pathology of the Stomach > Flashcards

S5) Function and Pathology of the Stomach Flashcards

1
Q

What do epithelial cells do in the stomach?

A

Epithelial cells cover the surface and extend into pits/glands

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2
Q

Identify 4 epithelial cells in the stomach

A
  • Mucous cells
  • Parietal cells
  • Chief cells
  • G cells
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3
Q

Identify the muscle layers in the stomach

A
  • Circular
  • Longitudinal
  • Oblique
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4
Q

What is the effect of stomach muscle contractions?

A
  • Mix/grind contents
  • Move contents along
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5
Q

What is the function of the upper stomach?

A

The upper stomach has sustained contractions (tonic) to create basal tone

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6
Q

The lower stomach is more muscular.

Describe its function

A

The lower stomach has strong peristalsis which mixes stomach contents

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7
Q

Describe how contractions occur in the stomach

A
  • Contractions are coordinated
  • Contractions occur every 20 seconds
  • Contraction are proximal to distal
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8
Q

What is receptive relaxation?

A

Receptive relaxation is the vagally mediated relaxation of orad stomach

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9
Q

What is the purpose of receptive relaxation?

A
  • Allows food to enter stomach without raising intra-gastric pressure too much
  • Prevents reflux of stomach contents when swallowing
  • Gastric mucosal folds (rugae) allow distension
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10
Q

Identify 3 functions of the acidic conditions of the stomach

A
  • Helps unravel proteins
  • Activates proteases: pepsinogen → pepsin
  • Disinfects stomach contents
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11
Q

Identify 4 substances which are secreted by the stomach

A
  • HCl
  • Intrinsic factor
  • Mucus/HCO3-
  • Pepsinogen (pepsin)
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12
Q

Identify the substances secreted from the following cells:

  • Parietal cell
  • G cell
  • Enterochromaffin like cell
A
  • Parietal cell: HCl & intrinsic factor
  • G cell: gastrin
  • Enterochromaffin like cell (ECL): histamine
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13
Q

Identify the substances secreted from the following cells:

  • Chief cell
  • D cells
  • Mucous cells
A
  • Chief cell: pepsinogen
  • D cells: somatostatin
  • Mucous cells: mucus
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14
Q

Identify the substances secreted from the following regions in the stomach:

  • Cardia
  • Fundus/body
  • Pylorus
A
  • Cardia: predominantly mucus secretion
  • Fundus/body: mucus, HCL, pepsinogen
  • Pylorus: gastrin, somatostatin
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15
Q

Identify the 3 substances which stimulate HCl production and state their origins

A
  • Gastrin from G cell
  • Histamine from ECL cells
  • Acetylcholine from vagus nerve
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16
Q

Where are G cells located?

A

G cells located in antrum

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17
Q

Identify the 2 factors which stimulate Gastrin secretion

A
  • Peptides/AA in stomach lumen
  • Vagal stimulation:

I. Acetylcholine

II. Gastrin-releasing peptide (GRP)

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18
Q

When food leaves the stomach, the pH drops.

How can HCl production be inhibted?

A
  • Low pH stimulates D cells which release somatostatin
  • Somatostatin inhibits G cells and ECL cells
  • Stomach distension reduces due to reduced vagal activity
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19
Q

Identify the 3 phases of digestion

A
  • Cephalic
  • Gastric
  • Intestinal
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20
Q

How much HCl is produced in the cephalic phase?

A

30% of total HCl

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21
Q

Outline the parasympathetic stimuli in the cephalic phase of digestion

A
  • Smelling, tasting, chewing, swallowing
  • Direct stimulation of parietal cells by vagus nerve
  • Vagus nerve releases GRP which stimulates of G cells
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22
Q

How much HCl is produced in the gastric phase of digestion?

A

60% of total HCl

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23
Q

State 4 events which occur in the gastric phase of digestion

A
  • Stomach distension stimulates vagus nerve
  • Vagus nerve stimulates parietal cells and G cells
  • Amino acids and small peptides stimulates G cells
  • Presence of food acts removes inhibition on Gastrin production (buffer)
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24
Q

What is the role of the enteric nervous system in the gastric phase of digestion?

A

ENS and gastrin causes strong smooth muscle contractions

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25
Q

How much HCl is produced in the intestinal phase of digestion?

A

10% of total HCl production

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26
Q

State the 4 events occurring in the intestinal phase of digestion

A
  • Chyme stimulates gastrin secretion due to the detection of partially digested proteins by duodenum
  • G cells are then inhibited
  • Enterogastric reflex is activated by lipids which reduces vagal stimulation
  • Chyme then stimulates CCK and secretin
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27
Q

Which substances are released to protect the stomach lining?

A
  • Mucus
  • HCO3-
28
Q

Where are mucus and hydrogen carbonate secreted from in the stomach?

A
  • Surface mucus cells
  • Neck cells in gastric glands
29
Q

What are the effects of mucus and hydrogen carbonate secretion in the stomach?

A
  • Thick alkaline viscous layer is formed which adheres to epithelium
  • Epithelial surface kept at higher pH
30
Q

Apart from mucus/HCO3-, identify and describe 2 other stomach defences

A
  • High turnover of epithelial cells to keep epithelia intact
  • Prostaglandins to maintain mucosal blood flow and supply epithelium with nutrients
31
Q

Identify 3 substances that breach the stomach defences and state their effects

A
  • Alcohol – dissolves mucus layer
  • Helicobacter pylori – causes chronic active gastritis
  • NSAIDS – inhibits prostaglandins
32
Q

Up to 40% of adults suffer from dyspepsia per year.

What is dyspepsia?

A

Dyspepsia is pain/discomfort in the upper abdomen

33
Q

Identify 6 common gastric disorders

A
  • Gastro-oesophageal reflux disease (GORD)
  • Gastritis
  • Peptic ulcer disease
  • Zollinger-Ellison disease
  • Stress ulcers
  • Stomach cancer
34
Q

What is GORD?

A

Gastro-oesophageal reflux disease (GORD) is a digestive disorder that affects the lower oesophageal sphincter and causes the reflux of stomach acid/contents into the oesophagus

35
Q

Identify 4 symptoms of GORD

A
  • Heartburn
  • Cough
  • Sore throat
  • Dysphagia
36
Q

Identify 4 causes of GORD

A
  • LOS problems
  • Delayed gastric emptying (raised intra-gastric pressure)
  • Hiatus hernia
  • Obesity
37
Q

Identify 3 compound problems which can arise from GORD?

A
  • Oesophagitis
  • Strictures
  • Barrett’s oesophagus
38
Q

Identify 3 types of treatment for GORD

A
  • Lifestyle modifications
  • Pharmacological
  • Surgery (rare)
39
Q

Identify 3 types of pharmacological treatments for GORD

A
  • Antacids
  • H2 antagonists
  • PPIs
40
Q

What is Barrett’s Oesophagus?

A
  • Barrett’s oesophagus is the metaplasia of squamous epithelium to columnar
  • It increases the risk of developing adenocarcinoma (30-40x)
41
Q

What is gastritis?

A

Gastritis is a condition involving the inflammation of the stomach lining

42
Q

What are the 2 types of gastritis which can occur in the body?

A
  • Acute
  • Chronic
43
Q

Acute gastritis is an acute mucosal inflammatory process.

Identify 4 of its causes

A
  • Heavy use of NSAIDS
  • Lots of alcohol
  • Chemotherapy
  • Bile reflux
44
Q

Identify the possible symptoms which may arise from acute gastritis

A
  • Either: asymptomatic
  • Or: pain, nausea, vomiting and occasional bleeding
45
Q

What are the 2 types of chronic gastritis which can occur in the body?

A
  • Autoimmune
  • Bacterial
46
Q

Compare and contrast the causes of chronic autoimmune and bacterial gastritis

A
  • Bacterial Gastritis – caused by H. pylori infection (commonly)
  • Autoimmune Gastritis – caused by antibodies to gastric parietal cells
47
Q

Identify a complication of chronic autoimmune gastritis

A

Autoimmune gastritis can lead to pernicious anaemia

48
Q

Identify the possible symptoms which may arise from chronic bacterial gastritis

A
  • Either: asymptomatic
  • Or: pain, nausea, vomiting and occasional bleeding
49
Q

In chronic bacterial gastritis, symptoms may develop due to complications.

Identify 3 of its complications

A
  • Peptic ulcers
  • Adenocarcinoma
  • MALT lymphoma
50
Q

Identify the symptoms of chronic autoimmune gastritis

A
  • Symptoms of anaemia
  • Glossitis
  • Anorexia
  • Neurological symptoms
51
Q

What is peptic ulcer disease?

A

Peptic ulcer disease is a condition which occurs when ulcers form and extend into the muscularis mucosae of the stomach due to defects in the gastric/duodenal mucosa

52
Q

Identify 2 common locations of peptic ulcers

A
  • Most common in first part of duodenum
  • Commonly affects lesser curve of stomach
53
Q

Peptic ulcer disease is caused by mucosal injury.

Identify 3 factors which may cause/contribute to this injury

A
  • Stomach acid
  • H. pylori
  • NSAIDS
54
Q

A major symptom of peptic ulcer disease is epigastric pain.

Describe the features of this pain

A
  • Burning/gnawing
  • Follows meal times
  • Often at night (especially DU)
55
Q

Identify 3 serious symptoms of peptic ulcer disease

A
  • Bleeding/anaemia
  • Satiety (early)
  • Weight loss
56
Q

What is Zollinger-Ellison syndrome?

A

Zollinger-Ellison syndrome is a condition when 1/more gastrin-secreting tumors (gastrinoma) form in your pancreas and duodenum

57
Q

What is stomach cancer?

A

Stomach cancer is a condition which involves tumour formation in the stomach lining

58
Q

Identify 4 different means of diagnosing gastric pathology

A
  • Upper GI endoscopy (biopsies/H-pylori)
  • Urease breath test
  • Erect chest X-ray (perforation)
  • Blood test (anaemia)
59
Q

Identify 3 ways of treating gastric pathologies

A
  • Eradicate H-pylori (PPI+ Clarithromycin + Amoxicillin)
  • Stop NSAIDS
  • PPIs
60
Q

Identify 2 pharmacological interventions for gastritis and provide examples for each

A
  • H2 blockers e.g. cimetidine, ranitidine
  • Proton pump inhibitors e.g. omeprazole
61
Q

Describe the structure, function and location of Helicobacter pylori

A
  • Structure: helix shaped, gram negative, flagellum
  • Function: produces urease, converts urea to ammonium, increases local pH
  • Location: mucus layer/adheres to gastric epithelia
62
Q

How does H.pylori spread?

A

Oral to oral/faecal to oral

63
Q

Identify 3 of H.pylori’s destructive functions

A
  • Releases enzymes (urease) causing direct epithelial injury
  • Degrades mucus layer
  • Promotes inflammatory response (self injury)
64
Q

State how the symptoms of H.pylori vary according to location

A
  • Antrum: duodenal ulceration
  • Antrum and body: asymptomatic
  • Body: leads to cancer
65
Q

Identify 5 causes of stress ulcerations

A
  • Severe burns
  • Raised intracranial pressure
  • Sepsis
  • Severe trauma
  • Multiple organ failure

(LUSUMA) Gastro-intestinal System (18 decks)

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