Nutrient Uptake in Gut Flashcards
ORS
oral rehydration salts
can small hydrophobic molecules enter traverse the cell membrane?
yes!
can ions traverse the cell membrane?
no!
can amino acids traverse the cell membrane?
no
can glucose traverse the cell membrane?
no
where is the epithelial cell?
lines the lumen of the gut
what lines the lumen of the gut?
an epithelial sheet
do the cells in epithelial sheets have polarity?
yes!
apical
top
basal
bottom
epithelial cells meet at a ________
tight junction
a _________ prevents anything from flowing between the cells
tight junction
is there a difference between the apical and basal sides of an epithelial cell?
yes, they’re polar
passive transporter for glucose
GLUT
the GLUT (passive transporter) switches conformation _________ and _________ between two states
randomly and reversibly
there are _____ different types of GLUT switches
12
transport without energy is ________
passive
transport requiring energy is _________
active
does a carrier mediated transporter use passive or active transport
both!
active transport is used when you’re going _________ the gradient
against
if a molecule is moving down the concentration gradient, it’s likely __________
passive
a ________ moves through a transporter
solute
a solute __________ through a transporter
moves
what’s a symport?
coupled transport in one direction
what’s an antiport?
co transportation in opposite directions
how does ORS work?
an active transporter (symport) uses the Na+ gradient (less in cell than out) to drive import of glucose against the gradient of glucose
cooperative binding
in active transporters, the binding of one molecule strongly increases binding affinity of another molecule
the active costransporter of glucose/Na+ is located on the _______ of the epithelial cell
apical
the the basal side of the epithelial cell, there are _____ glucose transporters
passive (channel)
the concentration of sodium (Na+) inside the cell is ______ than outside
lower
Why does sodium flow easily into the cell?
There’s a gradient because of the sodium/potasium antiport pump that pumps sodium outside the cell, against the gradient.
Why is the polarity of epithelial cells important?
because the cotransport symports are only located on the apical side of the cell, exposed to the lumen of the gut, while the potassium/sodium antiport pump is located on the basal side, along with the channel transports for glucose and other molecules. Because of this, there’s a perpetual sodium gradient into the cell, which allows sodium to act as a co-solute, aiding molecules to move against their gradient, into the cell, and then into the rest of the body.
why does ORS work?
water follows the solutes through osmosis
