Met Flashcards
Ferritin
Intracellular protein that acts as a buffer store of iron
ALP function
Can cause mobilisation of calcium and phosphate stores in bone to increase serum levels
Zonulin functions
Loosens tight junctions between epithelial cells of the gut lining is response to the presence of gliadin
Bacteria in Whipple disease
Tropheryma whipplei
Gram positive
Whipple disease pathophysiology
Lesions in intestinal walls
Damages billi
Also affects joints, CNS and CV systems
Diagnosis of Whipple disease
Duodenal biopsy
PAS positive staining macrophages
Pale yellow mucosa
Thickened mucosal folds
Whipple disease treatment
Penicillin, ampicillin, tetracycline, doxycycline
Vitamin supplements
Cholera toxin actions
Binds to enterocyte surface and taken up by endocytosis
Acvtiates a G protein that activates adenylyl cyclase
Increase IC cAMP levels
Overactivation of PKA
Phosphorylation of CFTR channel to open it
Large efflux of chloride ions
Water, sodium, potassium and bicarbonate follow
Rapid fluid loss leading to dehydration and diarrhoea
Define diarrhoea
Increased frequency of bowel evacuation with abnormally soft or liquid faeces with a volume of greater than 250g
Osmotic diarrhoea
Where the presence of unabsorbable products in the small intestine means that water remains in the intestines and is not absorbed
E.g. lactose intolerance
Secretory diarrhoea
Where substances are actviely trasnported into the gut lumen causing the secretion of water
E.g. cholera, salmonella
Inflammatory diarrhoea
Where bowel inflammation means the bowel is less able to absorb the products of digestion and water effectively
E.g. Crohn’s disease, ulcerative colitis
Complications of diarrhoea
Dehydration –> kidney failure, seizures, cerebral oedema, shrivelled skin, delirium, unconsciousness
Acid base imbalance - metabolic acidosis due to excessive bicarbonate loss
Malnutrition
Weight loss
Treatment of diarrhoea
ORS - glucose and sodium chloride
Diet - low fat, high fibre
Opiates (imodium) - slow transit time and increases anal sphincter tone
Bile acid sequesterants - prevents bile acids having an osmotic effect
Dietary water intake
2000-3000ml/day
Salivary secretions per day
1000-2000ml/day
Gastric juices per day
1000-2000ml/day
Bile secretions per day
500-1000ml/day
Pancreatic secretions per day
1000-2000ml/day
Intestinal secretions per day
1000-2000ml/day
How much water enters the colon per day?
1500ml/day
How much water is lost in faeces per day?
100-200ml/day
Why is water needed in the gut?
Hydrolysis reactions
Allows substances to be brought into close contact with intestinal walls
Mixes with mucin to make mucous
Propulsion of gut contents by peristalsis
How is gastric reflex prevented?
LOS tone
Acute angel where oesophagus enters stomach
Terminal oesophagus being within the abdominal cavity –> pressure collapses it
Contraction of the crural diaphragm exerts a pinch cock action on the oesophagus
Pathophysiology of heartburn
Acid entering the oesophagus can get through the epithelium
Activates spinal and vagal afferents
Travel to the CNS
Give the sensation of pain
Causes of heartburn
TLOSRs Weakened oesophageal epithelium Hypersensitivty to pain Hiatus hernia Increased intra-gastric pressure such as in obesity Decreased intra-abdominal pressure Shortened oesophagus
Risk factors for heart burn
Obesity Fatty foods Cabonated and caffeinated drinks Pregnancy Hiatus hernia Gastroparesis CCBs - relax LOS NSAIDs, SSRIs, bisphosphates, corticosteroids - irritation
Diagnosis of heartburn
Barium meal and x ray for obstructions Endoscopy for oesophagitis and masses Biopsy for Barret's oesophagus Ambulatory acid probe test Manometry
Treatment of heartburn/GORD
Actacids - neutralise stomach acid
PPIs - reduce action of H+/K+ ATPase in the parietal cells
H2 receptor antagonists - prevent binding of histamine to H2 receptors on parietal cells to decrease adenylyl cylase activation, cAMP production and therefore proton pump activation
Alginates - raft on stomach content surface
Baclofen - reduce TLOSRs
Macrolides - increase gastric motility
Surgery - fundoplication - creation of LOS with stomach
Tests for H. pylori
Urea breath test
Blood antibodies
Stool antibodies
Stomach biopsy
How does the urea breath test work?
Drink containing urea Breath into bag Air tested for CO2 levels Higher than normal CO2 = positive This is because the bacteria convert the urea into ammonia and carbon dioxide
Effects of hypoxia on EPO production
Decreased renal perfusion in hypoxia
Causes release of EPO from kidney
Causes increased RBC production in bone marrow
HIF-1 in hypoxia
Alpha subunits not degraded in hypoxia
HIF-1 can bind to promote regions of genes to promote their transcription
Upregulation of genes involved in glycogen breakdown and glycolysis
Suppression of mitochondrial fission and promotion of autophagy to reduce oxidative stress
Upregulation of VEGF to promote angiogenesis to increase tissue perfusion
Changes in glycogen breakdown in exercise
Calcium binds to calmodulin subunit of phosphorylase kinase
Activation of glycogen phosphorylase to increase glycogen breakdown
AMP also allosterically activates glycogen phosphorylase
Entry into TCA cycle in exercise
Controlled by PDC
PDC unregulated by calcium and ADP
Actions of AMP
Increases GLUT4 activity in muscles
Increases glycogen phosphorylase activity
Increases PFK-1 activity by activating AMPK which increases PFK2 action
Activates AMPK that inactivates ACC to prevent lipogenesis and promote fatty acid break down
