Extra lab questions Flashcards
What is the 24 h intragastric pH profile?
Approximately 3 waves of increase intragastric pH; corresponding to main meals of the day, ranges from 3 to 1 pH of 1 during the night
What are the factors that affects the intragastric pH profile?
How often one eats Type of food Amount of fluids Drugs
Name the methods to diagnose Helicobacter pylori infection
Breath test - most accurate Stool antigen Blood test - antibody Histological biopsy
Explain the breath test for diagnosing H pylori infection
Testing for urease activity Bacteria synthesise CO2 from the urea and thus the %CO2 determines the urease activity
- Describe the mechanism by which Helicobacter pylori infection predisposes to duodenal ulcer disease
a. (NH2)2CO2 + H20 —> CO2 + 2 NH3 b. Ammonia makes mucous cloud around the lumen of the epithelium c. This sends message that the pH is too high and increased secretion of acid is stimulated d. Some evidence that bacteria causes also inflammation
What are the protective mechanisms of the oesophagus?
- Intrinsic sphincter - Extrinsic sphincter - Intra-abdominal oesophagus - Angle of His/Flap valve - Secondary peristalsis
What are the results of failure of protective mechanisms of the oesophagus?
Impaired defences ○ Hiatus hernia ○ Transient lower oesophageal relaxations ○ Low sphincter pressure ○ Impaired oesophageal clearance Increased offences ○ Increased intra-abdominal pressure ○ Reduced gastric emptying
What are the characteristics of the greater omentum?
Covers the bowel Under ventral abdominal wall Blocks possible openings Helps to stop infection Attached to tranverse colon
What are the spaces between liver and diaphragm and what divides them?
Left and right subphrenic spaces divided by fold of peritoneum called Falciform ligament
What is ligamentum teres?
Round ligament at the bottom of Falciform lig; remnant of the umbilical vein which became fibrous core
What is the infra-colic compartment?
Space behind greater omentum below transverse colon
What is lesser omentum?
Covers the stomach and other organs, has the omental bursa
What is epiploic foramen?
Also omental foramen, passage between the greater and lesser sacs
What are the 2 types of hiatus hernia?
Sliding type Rolling type - stomach slips in
What are the tests used to assess pancreatic function?
Test for reducing sugars - tests for the extent of digestion of carbohydrates as only the last carbon in the chain has reducing powers
Which cells store the normal and abnormal fat in steatosis of the liver?
Normal - parasinusoidal cells Abnormal - Hepatcytes
How are drugs removed by the liver?
Lipid soluble drugs are converted to water soluble by the liver, these are excreted in urine Phase I and phase II metabolisms
Describe phase I metabolism for removal of drugs by the liver
Dependent on cytochrome P450 enzyme system; produces more polar metabolites by oxidation, reduction and hydrolysis
Describe phase II metabolism for removal of drugs by the liver
Converts parent drug into a more polar form by combining it with glycine, glutamine, sulphate or glucuronic acid; or by adding an acetyl or a methyl group
What is therapeutic range?
Concentration that causes the desired effect vs the concentration that causes toxic effects; usually associated with blood concentration
Describe the changes to fluid volume in diarrhoea associated with NaCl and water loos
Dehydration -> decreased glomerular filtration rate and tubular luminal flow rate -> increased tubular reabsorption -> rise in serum urea -> significant reduction in extracellular fluid volume
What factors control the composition of the gut bacterial flora?
Physiochemical - pH, nutrients Host-bacteria interactions - secretions, immune system Microbe-microbe interactions - Bacteriophages, toxic metabolites
What is the range of potentially harmful metabolic activity of the colonic flora
Hydrolysis, aromatization, reduction, synthesis, degraduation
What are the potential harmful products of the colonic flora?
Carcinogens and toxins, azo dyes, phenols and paracresols, H2S, hydroxy fatty acids, secondary bile acids
