lecture 27

Question 1

what are the sites of absorption in the body

Answer 1

minimal in the mouth, esophagus and stomach.
small intestine has 90% of Na+ and water and all food molecules
large intestine has remainder of Na+ and water

Question 2

how does motility affect absorption

Answer 2

motility is the correct amount of time so that enough is absorbed into the body, not too much as otherwise constapation

Question 3

how does removal from interstitial fluid affect absorption

Answer 3

flow of fat into the lymphatics and nutrients into blood prevent build up in the interstitial fluid. which means solutes can be moved out of cells as conc gradient always exists.

Question 4

around how much water do we secrete to si in a day

Answer 4

9-10L, we reabsorb most but then replace what we don’t absorb

Question 5

osmosis is mostly done by

Answer 5

the paracellular pathway

Question 6

first part in fat absroption

Answer 6

the micelle isnt absorbed as the bile salts are absorbed in ileum. the micelle gets close to the brush boarder so then the fat products can diffuse in

Question 7

where are bile salts reabsorbed, in the large intestine

Answer 7

n the ileum

Question 8

seconf part of fat absorption

Answer 8

the fat breakdown products are transported to the ER. they are made made into TAGs to maintain apical diffusion gradient. they are expelled from golgi as the chylomicrons

Question 9

3 part of fat absorption

Answer 9

chylomicrons are exocytosed and they then enter the lymph vessels

Question 10

how are bile salts reabsorbed

Answer 10

absorbed in the ileum by na+ cotransport

Question 11

how is vitamin B12 reabsorbed

Answer 11

its absorbed in the ileum. to be absorbed it first binds to intrinsic factor from the stomach. Once in the cell the B12 unbinds to ensure conc gradient. B12 is then rebound to another protein to allow the transport of the vitamin in blood.