fluid absorption and cholera

Question 1

how many litres of water do we get a day from food and drink

Answer 1

2L

Question 2

how much water is absorbed in the small intestine compared to the large intestine

Answer 2

400ml per day in the large intestine

8500 ml per day in the small intestine

Question 3

how much water do we loose a day in excretion

Answer 3

about 100ml

Question 4

what follows ion uptake in the intestines

Answer 4

water via osmosis following the gradient

Question 5

how do ions pass into the interstitium in the duodenum and the jejunum

Answer 5

paracellular routes

Question 6

how do ions pass through the ileum

Answer 6

transcellularly

Question 7

what two ways are ions absorbed in the ileum of the small intestine

Answer 7

na cl symporter from the lumen into the cell
co transporters, hco3 with cl
na with H

Question 8

describe the mechanism of a symporter

Answer 8

symporter on apical membrane transfers cl and na into the cell
K/Na active transport on basolateral surface - k into the cell and na out into ECF
k leaks out cell into ECF and so does Cl

Question 9

describe the antitrasnporter system of the colon and the ileum

Answer 9

in the cell: water and co2 make HCO3 and H+
apical membrane: HCO3 out and Cl in
Na in and H out into lumen
basolateral membrane: na into ecf and K into cell via active transport
k leaks out
cl leaks out

Question 10

what transport system occurs only in the colon

Answer 10

Na passively in on apical
k leaks out on apical
na out k in active transport on basolateral
k leak out on basolateral

Question 11

why is ORS good in cholera

Answer 11

SGLT absorbs glucose and na quickly so water travels with them out the lumen

Question 12

in what forms do calcium travel in the blood

Answer 12

bound to proteins or as inorganic ca2+w

Question 13

where does calcium absorption normally occur

Answer 13

in the duodenum and jejunum

Question 14

what increases the amount of ca absorption

Answer 14

vitamin D3 which gets transformed in the liver then the kidney to calcitrol which causing increase in number of ca binding proteins available on the lumen of the cells
also parathyroid increases metabolism of vitamins d3 to calcitrol to increase ca absorption

Question 15

describe the process of ca absorption

Answer 15

ca binds to ca binding protein on the apical membrane - ca then either sequesters in the er or bind to proteins in the cell
ca moves out the basolateral side via ca atpase or by na ca antitransporter

Question 16

where do we get absorbed iron from

Answer 16

meat and pants in diet and absorption of heme

Question 17

what must happen to iron to be absorbed

Answer 17

reduced from iron 3 to iron 2 as iron 3 is insoluble

Question 18

what reduces iron 3 to iron 2

Answer 18

low ph in the stomach favours the reduction

reductase enzyme present on the apical surface

Question 19

what are the two ways iron is absorbed

Answer 19

via endocytosis of heme - heme is then broken down by heme oxygenase - this produce biliverdin which is removed by bile salts - also produces CO and fe 3+ which is reduces in the cell to fe2+
fe 2+ is absorbed with H+ co transporter into the cell

Question 20

how do iron leave the basolateral membrane

Answer 20

fe2+ binds to mobilferrin which binds to the surface to release fe2+ across where it binds to plasma transferrin

Question 21

what happens if we have to high a conc of iron in our system

Answer 21

causes production of ROS and therefore dan damage

Question 22

why do we need to eat vitamins

Answer 22

they are not made in the body

Question 23

what are the two types of vitamins

Answer 23

fat soluble and water soluble

Question 24

what are the fat soluble vitamins

Answer 24

A, D, E, K - follow absorption with micelles and chylomicrons

Question 25

what are the water soluble vitamins

Answer 25

vit b 12
1, 2, 6
folic acid
vit c

Question 26

how is vitamins b absorbed

Answer 26

in food b12 is bound to proteins
in the stomach the proteins are broken down and b12 binds to r protein
it then travels to the small intestine where proteases break down R protein and it binds to intrinsic factor
endocytosis occurs in the small intestine
it is carried in the plasma by transcobalamin 2