Case 2 - overview of the gastointestinal tract Flashcards
what does the small intestine absorb
80% ingested water
Electrolytes
Vitamins
Minerals
Carbohydrates
Active/facilitated transport
Monosaccharides
proteins
Di/tri-peptides
Amino acids
lipids
Monoglycerides
Fatty acids
Micelles
Chylomicrons
what are the digestive enzymes the SI secretes
peptidases
Amino
Di
Tri
sucrases
Maltase
Lactase
Saccharidases
Di
Tri
lipase
Nucleases
what does the small intestine require to complete digestion
pancreatic enzymes
where is the only place we find brunners glands
the duodenum
where is the bulk of absorption usuallt
the jejunum
what is cobalamin
vitamin B12
where is iron absorbed
only in the duodenum and absorbed the earliest
what does loss of cells at the villi tips in the small intestine lead to
release of enzymes into the lumen
how much fluid do crypt cells secrete
around 2-3 litres of isotonic fluid a day
what type of transport is glucose uptake in the small intestine
coupled transport process
what pumps sodium out of the basolateral membrane
the sodium potassium ATPase pump
what does this lead ro
drives the sodium-glucose symporter in the apical membrane
what is step one of fat absorption i the small intestine
large fat globules are emulsified by bile salts in the duodenum
what is step two of fat absorption in the small intestine
digestion of fat by the pancreatic enzyme lipase yields free fatty acid and monoglycerides whcih then form micelles
what is step three of fat absorption in the small intestine
fatty acids and mono glycerides leave micelles and enter epithelial cells by diffusion
what is step four of fat absoprtion in the small intestine
Chylomicrons containing fatty substances are transporter out of the epithelial cells and into lacteals, where they are carried away from the intestine by lymph.
what are micelles made up of
Micelles are made up of fatty acids, monoglycerides and bile salts
what is a good target in the treatment of obesity
the pancreatic lipase
orlistat mechanism of action
inhibits lipase and significantly reduces fat absoption
what are the effects of alli (orlistat)
Response depends on the patient’s diet, and undesired effects include an increase in the number and nature of bowel movements, abdominal discomfort, oily stools, flatulence and oily spotting in underwear
what kind of fat diet can humans survive on
survive on a diet of 1% fat but normal is around 20-30% so we overeat vastly
what is short bowel syndrome
Problems may occur at less than 200cm of functional small intestine
SBS results in a malabsorptive state
Due to insufficient absorptive surface area
Can result in fluid and electrolyte imbalances as well as poor nutritional status
Potential ‘failure to thrive’ in infants
May be congenital, as a result of surgical resection, or changes in blood supply to the SI
Prognosis improves with increasing length of remaining intestine
where are most carbohydrates, proteins and fats absorbed in the jejunum
first 100-150 cm
what is normal length of small intestine
600cm
what is the treatment of SBS
parenteral nutrition and increasingly intestinal transplant
what BMi do u have to have to have bariatric surgery
BMI over 40kg per m2
what are the techniques of bariatric surgery
Gastric banding
Gastric bypass: smaller stomach pouch, and shortening of intestine - without removing the intestine (permanent)
Biliopancreatic diversion: removal of portion of the stomach, and diversion of bile and pancreatic juices
