Flashcards in Small Intestine and pharmacology Deck (57)
What is SGLT1?
Na/glucose co transporter in small intestine which takes these molecules from lumen to blood. Na down conc gradient, glucose against
Describe blood supply to jejunum and ileum
Supplied by SMA
Branches into ileocolic artery
Which branches into jejunal and ileal
How can one distinguish between jejunum and ileum?
Jejunum - long vasa recta, 1/2 arcades, wide bore, thick folded wall
Ileum - short vasa recta, multiple arcades, narrow bore, thin smooth wall
What is the risk of proximal duodenal ulcers?
Perforation of gastroduodenal artery which will bleed profusely
Describe the blood supply to the duodenum
Proximal supplied by coeliac trunk - gastroduodenal and superior pancreaticoduodenal
Distal supplied by SMA - inferior pancreaticoduodenal
What does the Ligament of Treitz provide a good landmark for? And where does it originate?
Originates at diaphragm
Name 4 symptoms of malabsorption
What deficiencies can cause malabsorption?
Brush border enzyme deficiency
Pancreatic enzyme secretion deficiency
Bile secretion deficiency
What happens to the SI in coeliac disease?
Lining becomes sensitive to gluten
This causes damage to the mucosa
So the ability of the SI to absorb fats is affected
Why does lactose intolerance result in diarrhoea?
Bacteria in colon digest lactose which the SI is unable to due to a deficiency of lactase brush border enzymes. The monosaccharides cannot be absorbed here and so create an osmotic drag, pulling water into the lumen and causing diarrhoea
What is Vit B12 bound to in the stomach and how is that different from the SI?
R protein in stomach
Intrinsic factor in SI
What 3 things are required for the absorption of fat to take place?
What are micelles in the SI?
Globule containing monoglycerides and fatty acids
Surrounded by bile salts and phospholipids
Formation and break down of micelles in equilibrium so some free fatty acids which can diffuse into the epithelial cells
Can also carry fat soluble vitamins
How do reassembled fats in the epithelial cells get out?
Triglycerides are packaged into chylomicrons which are exported across the basolateral membrane to leave intestinal villus via lymph vessel as they are too big to pass into the blood stream
How does the emulsification of fats aid absorption?
Larger surface area for pancreatic lipase to have its effect
Make it more water soluble
Which 4 enzymes are responsible for protein/peptide digestion in the SI?
Aminopeptidase - brush border enzyme
Which ion are amino acids usually cotransported with during absorption?
What are maltase, lactase and fructase?
Brush border enzymes which convert disaccharides into monosaccharides
Which vitamin facilitates the absorption of Ca?
Which molecule does iron bind to within epithelial cells for storage?
In what circumstance would iron storage be depleted?
Reduced iron content in blood eg haemorrhage
What are alginates?
Anionic polysacharrides which form a raft like gel layer on top of the stomach contents to reduce the symptoms of acid reflux
What do magnesium salts, aluminium salts and bicarbonate salts have in common?
Antacids used to reduce acidity of stomach acid to help reduce acid reflux
Give 2 uses of Misoprostol
Prevent gastric damage caused by chronic NSAID use
What is cimetidine?
Histamine H2 antagonist
What caution should be taken when prescribing cimetidine?
Dose given to those with hepatic and renal impairment
And in women who are pregnant or breast feeding
What would bismuth chelate be used for generally?
In a combination regimen to treat H pylori involvement of peptic ulcers
Give 4 ways that bismuth chelate has its desired effect
Enhances local prostaglandin synthesis
Stimulates bicarbonate secretion
Name 2 side effects of bismuth chelate
Nausea and vomiting
Reversible blackening of tongue and faeces