Case 2 - overview of the gastointestinal tract

Question 1

what does the small intestine absorb

Answer 1

80% ingested water
Electrolytes
Vitamins
Minerals
Carbohydrates
Active/facilitated transport
Monosaccharides
proteins
Di/tri-peptides
Amino acids
lipids
Monoglycerides
Fatty acids
Micelles
Chylomicrons

Question 2

what are the digestive enzymes the SI secretes

Answer 2

peptidases
Amino
Di
Tri
sucrases
Maltase
Lactase
Saccharidases
Di
Tri
lipase
Nucleases

Question 3

what does the small intestine require to complete digestion

Answer 3

pancreatic enzymes

Question 4

where is the only place we find brunners glands

Answer 4

the duodenum

Question 5

where is the bulk of absorption usuallt

Answer 5

the jejunum

Question 6

what is cobalamin

Answer 6

vitamin B12

Question 7

where is iron absorbed

Answer 7

only in the duodenum and absorbed the earliest

Question 8

what does loss of cells at the villi tips in the small intestine lead to

Answer 8

release of enzymes into the lumen

Question 9

how much fluid do crypt cells secrete

Answer 9

around 2-3 litres of isotonic fluid a day

Question 10

what type of transport is glucose uptake in the small intestine

Answer 10

coupled transport process

Question 11

what pumps sodium out of the basolateral membrane

Answer 11

the sodium potassium ATPase pump

Question 12

what does this lead ro

Answer 12

drives the sodium-glucose symporter in the apical membrane

Question 13

what is step one of fat absorption i the small intestine

Answer 13

large fat globules are emulsified by bile salts in the duodenum

Question 14

what is step two of fat absorption in the small intestine

Answer 14

digestion of fat by the pancreatic enzyme lipase yields free fatty acid and monoglycerides whcih then form micelles

Question 15

what is step three of fat absorption in the small intestine

Answer 15

fatty acids and mono glycerides leave micelles and enter epithelial cells by diffusion

Question 16

what is step four of fat absoprtion in the small intestine

Answer 16

Chylomicrons containing fatty substances are transporter out of the epithelial cells and into lacteals, where they are carried away from the intestine by lymph.

Question 17

what are micelles made up of

Answer 17

Micelles are made up of fatty acids, monoglycerides and bile salts

Question 18

what is a good target in the treatment of obesity

Answer 18

the pancreatic lipase

Question 19

orlistat mechanism of action

Answer 19

inhibits lipase and significantly reduces fat absoption

Question 20

what are the effects of alli (orlistat)

Answer 20

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

Question 21

what kind of fat diet can humans survive on

Answer 21

survive on a diet of 1% fat but normal is around 20-30% so we overeat vastly

Question 22

what is short bowel syndrome

Answer 22

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

Question 23

where are most carbohydrates, proteins and fats absorbed in the jejunum

Answer 23

first 100-150 cm

Question 24

what is normal length of small intestine

Answer 24

600cm

Question 25

what is the treatment of SBS

Answer 25

parenteral nutrition and increasingly intestinal transplant

Question 26

what BMi do u have to have to have bariatric surgery

Answer 26

BMI over 40kg per m2

Question 27

what are the techniques of bariatric surgery

Answer 27

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