Nutrient Uptake in Gut

Question 1

ORS

Answer 1

oral rehydration salts

Question 2

can small hydrophobic molecules enter traverse the cell membrane?

Answer 2

yes!

Question 3

can ions traverse the cell membrane?

Answer 3

no!

Question 4

can amino acids traverse the cell membrane?

Answer 4

no

Question 5

can glucose traverse the cell membrane?

Answer 5

no

Question 6

where is the epithelial cell?

Answer 6

lines the lumen of the gut

Question 7

what lines the lumen of the gut?

Answer 7

an epithelial sheet

Question 8

do the cells in epithelial sheets have polarity?

Answer 8

yes!

Question 9

apical

Answer 9

top

Question 10

basal

Answer 10

bottom

Question 11

epithelial cells meet at a ________

Answer 11

tight junction

Question 12

a _________ prevents anything from flowing between the cells

Answer 12

tight junction

Question 13

is there a difference between the apical and basal sides of an epithelial cell?

Answer 13

yes, they’re polar

Question 14

passive transporter for glucose

Answer 14

GLUT

Question 15

the GLUT (passive transporter) switches conformation _________ and _________ between two states

Answer 15

randomly and reversibly

Question 16

there are _____ different types of GLUT switches

Answer 16

12

Question 17

transport without energy is ________

Answer 17

passive

Question 18

transport requiring energy is _________

Answer 18

active

Question 19

does a carrier mediated transporter use passive or active transport

Answer 19

both!

Question 20

active transport is used when you’re going _________ the gradient

Answer 20

against

Question 21

if a molecule is moving down the concentration gradient, it’s likely __________

Answer 21

passive

Question 22

a ________ moves through a transporter

Answer 22

solute

Question 23

a solute __________ through a transporter

Answer 23

moves

Question 24

what’s a symport?

Answer 24

coupled transport in one direction

Question 25

what’s an antiport?

Answer 25

co transportation in opposite directions

Question 26

how does ORS work?

Answer 26

an active transporter (symport) uses the Na+ gradient (less in cell than out) to drive import of glucose against the gradient of glucose

Question 27

cooperative binding

Answer 27

in active transporters, the binding of one molecule strongly increases binding affinity of another molecule

Question 28

the active costransporter of glucose/Na+ is located on the _______ of the epithelial cell

Answer 28

apical

Question 29

the the basal side of the epithelial cell, there are _____ glucose transporters

Answer 29

passive (channel)

Question 30

the concentration of sodium (Na+) inside the cell is ______ than outside

Answer 30

lower

Question 31

Why does sodium flow easily into the cell?

Answer 31

There’s a gradient because of the sodium/potasium antiport pump that pumps sodium outside the cell, against the gradient.

Question 32

Why is the polarity of epithelial cells important?

Answer 32

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.

Question 33

why does ORS work?

Answer 33

water follows the solutes through osmosis