sodium-dependent glucose transporter protein
tight junctions divide cells into ?
apical and basolateral membrane domains
how are the ion gradients necessary for glucose absorption set up?
____ uses energy from Na+ gradient to actively accumulate glucose above its ________ ________
_SGLT_ uses energy from Na+ gradient to actively accumulate glucose above its _Concentration_ _gradient_
glucose exits the cell facilitated by _____ transport proteins in the _______ membrane domain, by ________ ________
glucose exits the cell facilitated by _GLUT_ transport proteins in the _basolateral_ membrane domain, by _passive_ _diffusion_
what happens to the Na+ which also enters the cell with glucose?
exits via basolateral Na-pump
how is osmotic imbalance (due to glucose and Na+ and glucose moving across epithelium) equilibriated ?
paracellular Cl- (down electrical gradient) and water (concentration gradient) fluxes
direction of transport through GLUT
either way, depends on concentration gradient
oral rehydration therapy
exploits ability for glucose to increase Na+ absorption and hence Cl- and WATER
dehydrated babies with diarrhoea given...
simple sugar solution to orally rehydrate them. responsible for saving millions of babies erry year
glucose/galactose malabsorption syndrome caused by?
mutation causing gene 1 for glucose symporter, SGLT (in the small intestine), to be knocked-out
consequence of glucose/galactose malabsorption syndrome
glucose/galactose accumulate in the lumen of the small intestine, therefore the osmotic imbalance causes water to enter the lumen - ending in watery chyme aka diarrhoea
treatment of glucose/galactose malabsorption syndrome
- removal of glucose/galactose from diet - fructose used as carbohydrate source - fructose uses GLUT 5, a facilitative transporter specific to fructose
how many litres of body fluid filtered by Kidneys per day?
180 litres per day
what will happen if all the glucose filtered out of the blood isn't reabsorbed?
glucose in urine. sweet piss.
glucose accumulating in the urine
when does glucosuria occur?
when SGLT protein cannot absorb all the glucose fast enough because the transport maximum of SGLT is exceeded i.e. the renal threshold is surpassed
most common cause of glucosuria
diabetes melitus, becuase blood sugar is too high (over 200mg/100mL) due to deficient insulin activity
renal threshold =
~200mg/100mL blood plasma. this is the maximum that SGLT can deal with
Which protein transports fructose?
which number shows...
- transport maximum
- renal threshold
1 = renal threshold
2 = transport maximum