Gastro Flashcards
What does maltase do?
cleaves disaccharide maltose to glucose + glucose
What does sucrose do?
cleaves sucrose to fructose and glucose
what does galactose do?
cleaves disaccharide lactose to glucose + galactose
What is the source/stimulus/actions of gastrin?
G cells in antrum of the stomach
Stimulated by:
Distension of stomach, vagus nerves (mediated by gastrin-releasing peptide), luminal peptides/amino acids
Inhibited by:
• low antral pH • somatostatin
↑ HCL= Increases acid secretion by gastric parietal cells, pepsinogen and IF secretion, increases gastric motility, stimulates parietal cell maturation
What is the source/stimulus/actions of CCK?
I cells in upper small intestine
Stimulated by:
Partially digested proteins and triglycerides
↑ secretion of enzyme-rich fluid from pancreas, contraction of gallbladder and relaxation of sphincter of Oddi, ↓ gastric emptying, trophic effect on pancreatic acinar cells, induces satiety
what is the source/stimulus/actions of secretin?
S cells in upper small intestine
Stimulated by:
Acidic chyme, fatty acids
↑ secretion of bicarbonate-rich fluid from pancreas and hepatic duct cells, ↓ gastric acid secretion, trophic effect on pancreatic acinar cells
what is the source/stimulus/action of VIP?
Small intestine / pancreas
Stimulated by:
Neural
Stimulates secretion by pancreas and intestines, inhibits acid and pepsinogen secretion
what is the source/stimulus/action of somatostatin?
D cells in the pancreas & stomach
Stimulated by:
Fat, bile salts and glucose in the intestinal lumen
↓ acid and pepsin secretion, ↓ gastrin secretion, ↓ pancreatic enzyme secretion, ↓ insulin and glucagon secretion
inhibits trophic effects of gastrin, stimulates gastric mucous production
what are the 3 principle mediators of acid secretion?
Principle mediators of acid secretion
• Gastrin
• Vagal stimulation
• Histamine
what are 4 factors that will increase acid secretion?
Factors increasing acid secretion
• Gastrinoma
• Small bowel resection (removal of inhibition)
• Systemic mastocytosis (elevated histamine levels)
• Basophilia
what are 2 factors that will decrease acid secretion?
Factors decreasing acid secretion
• Drugs: H2-antagonists, PPIs
• Hormones: secretin, VIP, GIP, CCK
What is a pharyngeal pouch?
–where is this situated anatomically?
-who is this most commonly found in?
Pharyngeal Pouch is a posteromedial diverticulum or herniation through Killian’s dehiscence.
Killian’s dehiscence is a triangular area in the wall of the pharynx between the thyropharyngeus and cricopharyngeus muscles.
It is more common in older patients and is 5 times more common in men
what are 5 features of pharyngeal pouch?
Features
• Dysphagia
• Regurgitation
• Aspiration
• Neck swelling which gurgles on palpation
• Halitosis (noticeably unpleasant odors exhaled in breathing)
what is travellers diarrhoea?
Travellers’ diarrhea may be defined as at least 3 loose to watery stools in 24 hours with or without one or more of abdominal cramps, fever, nausea, vomiting or blood in the stool.
what is the most common cause of travellers diarrhoea?
-what are the clinical features?
-what is the incubation period?
The most common cause is Escherichia coli
Watery stools
Abdominal cramps and nausea
12-48hours
what is ‘acute food poisoning’? and what are the typical causes?
Another pattern of illness is ‘acute food poisoning’. This describes the sudden onset of nausea, vomiting and diarrhea after the ingestion of a toxin. Acute food poisoning is typically caused by Staphylococcus aureus, Bacillus cereus or Clostridium perfringens.
which pathogen causes Prolonged, non-bloody diarrhea?
what should be found in stool?
what is the treatment?
Giardiasis
Diagnosis – look for cysts or parasites in stool
Treatment – metronidazole
which pathogen causes Profuse, watery diarrhea?
what is this commonly assoc with?
Cholera
toxin mediated disease often associated with outbreaks – refugee camps
uncommon
which pathogen causes bloody diarrhoea?
-what are other features?
-what is the incubation period?
Shigella
Vomiting and abdominal pain
48-72 hours
which pathogen causes severe vomiting?
-what is the incubation period?
-what foods are assoc?
Staph. Aureus
short incubation
Foods that have been frequently implicated in SFD are meat and meat products, poultry and egg products, milk and dairy products, salads, bakery products, especially cream-filled pastries and cakes, and sandwich fillings
which pathogen causes a flu-like prodrome
followed by crampy abdominal pains
fever and diarrhoea which may be bloody?
-what syndrome is assoc with this?
-is this common?
-what is the incubation period?
Campylobacter
complications included guillian barre
most common cause in the UK
48-72 hrs
which pathogen causes 2 types illness:
vomiting within 6 hours
diarrhoeal illness occurring after 6 hours
-what food assoc exists?
-what is the incubation period?
Bacillus cereus
-Bacillus cereus infection most commonly results from reheated rice
-1-6hrs
which pathogen causes Gradual onset bloody diarrhea abdominal pain and tenderness may last for several weeks?
-what seen on stool microscopy?
-what is treatment with?
-what can this disease also cause?
Amoebiasis
-stool microscopy may show trophozoites if examined within 15 minutes or kept warm (known as a ‘hot stool’)
-Treatment is with metronidazole
-Treatment for invasive amoebiasis should be followed by a luminal amoebicide to eradicate the cystic stage which is resistant to metronidazole and tinidazole (which are used against the invasive stage).
-Amoebiasis also causes liver and colonic abscesses.
describe the liver abscesses caused by amoebiasis?
-where abouts is this found?
-what 2 clinical features are seen?
-what investigations can be done?
usually a single mass in the right lobe (may be multiple). The contents are often described as ‘anchovy sauce’
features: fever, RUQ pain
serology is positive in > 90%