Lecture Four: Glucose Absorption

_____ membrane is the one next to the lumen and the _______ membrane is the one next to like blood lol (in contact with basement membrane tho)

apical, basolateral

renal threshold: is the _______ of a substance dissolved in the blood above which the kidneys begin to _______ it into the urine

concentration, remove

Sodium absorption occurs in two stages. The first is via intestinal epithelial cells. Sodium passes into cells by ________ with glucose, (SGLT1 protein). Then sodium is pumped by active transport (sodium-potassium pump) through the ________ cell membrane into the extracellular space.

cotransport, basolateral

Glucose and sodium are ________ across the basolateral membrane by _________ diffusion.

cotransported, facilitated

Treatment for glucose/galactose malabsorption: removal of glucose & galactose from diet & use ______ as sort of carbohydrate. This uses facilitative transporter specific for _______

fructose, fructose

______ exits the cell across the basolateral membrane by facilitated diffusion mediated by the _____ transporter protein

glucose, GLUT

Renal glucose reabsorption: retrieval of filtered ______, preventing it from disappearing from the body through the ______.

glucose, urine

______: accumulation of glucose in urine

glucosuria

Facilitative glucose transporter mediates glucose exit across the basolateral membrane via passive diffusion down its __________

gradient

The Na/K pump sets up _____ ______

ion gradients

SGLT2 is a protein in humans that facilitates glucose reabsorption in the _______.

kidney

________ is the inside space of a tubular structure, such as an artery or intestine

lumen

Glucosuria occurs when transport _______ for _____ protein exceeded.

maximum, SGLT

The ability of glucose to enhance the absorption of Na+ (and thus Cl- and water) means simple sugar solution can be given to babies suffering from diarrhoea. Called _____ ______ ______

oral rehydration therapy

The movement of glucose across the epithelium creates ______ imbalance (which drives the absorption of water)

osmotic

The transport of Na+ and glucose across epithelium induces ______cellular Cl- and H2O fluxes

para

In a diarrheal illness, sodium-rich intestinal secretions are lost before they can be __________.

reabsorbed

If glucose is not _______ by the kidney, it appears in the _____

reabsorbed, urine

All filtered glucose is _______ until renal threshold is reached

reasorbed

_______ ____ reflects transport maximum of SGLT

renal threshold

SGLT proteins use energy from this downhill sodium gradient to transport glucose across the apical membrane of the cell against the glucose gradient. Thus the co-transporters are examples of ________ active transport.

secondary

Glucose/galactose malabsorption syndrome results in accumulation of glucose & galactose in lumen of _____ _______ - producing _____ imbalance (attracting water = severe diarrhoea)

small intestine, osmotic

The energy for glucose entry is supplied by the ______ gradient

sodium

Two ______ ions and one molecule of glucose (or galactose) are transported together across the cell membrane via the SGLT1 protein into epithelial cells

sodium

Na+ taken up via the _____ _______ ____ and exits via the basolateral _____ pump

sodium glucose symporter, Na/K

Without glucose, intestinal _____ is not absorbed. This is why oral rehydration salts include both ______ and glucose. Water molecules move into the epithelial cell to maintain _______ equilibrium. The resultant absorption of sodium and water can achieve rehydration.

sodium, sodium, osmotic

Common cause of glucosuria = diabetes mellitus (deficient insulin & blood sugar too high). Glucose _____ can not absorb glucose fast enough & glucose appears in urine.

symporter

The sodium glucose ______ uses the energy of the Na+ gradient to actively accumulate glucose above its concentration gradient

symporter

A ________ is an integral membrane protein that is involved in the transport of many differing types of molecules across the cell membrane. Molecules are transported across the cell membrane at the same time, and is, therefore, a type of _____transporter.

symporter, co

Both SGLT1 and SGLT2 are known as _________, since both sodium and glucose are transported in the same direction across the membrane.

symporters

____ ____ divide cells into apical and basolateral membrane domains

tight junctions

If glucose absorption impaired or saturated _________, glucose will appear in the urine

transporter

Glucose transport is a _ step process

2

Glucose/galactose malabsorption syndrome is caused by a mutation in sodium-dependent glucose (co-) transporter (_______) protein.

SGLT