9/12/22

Question 1

glucose-Na+ symport

Answer 1

drives active transport of glucose

Question 2

glucose-Na+ symport is highly effective in what state?

Answer 2

fasting state (low glucose load)
can get saturated when glucose load increases

Question 3

glucose-Na+ symport works in what direction?

Answer 3

it is unidirectional
can’t release glucose from cell into extracellular space upon need

Question 4

2 problems of glucose-Na+ symport

Answer 4

1) gets saturated when glucose load increases
2) unidirectional: can’t release glucose from cell into extracellular space upon need

Question 5

how do we fix glucose-Na+ symport problems?

Answer 5

GLUT family

Question 6

uncoupling agents

Answer 6

make pores in cell membrane
dissipate proton gradient –> must spend more energy to restore

Question 7

SGLT

Answer 7

sodium-glucose linked transporter
actively takes up glucose from gut

Question 8

GLUT

Answer 8

glucose transporter
passively releases glucose for use by other tissues

Question 9

NaK pump in epithelial cells is found in

Answer 9

basolateral membrane

Question 10

Na promotes

Answer 10

depolarization

Question 11

intestine transport

Answer 11

electrolytes and water

Question 12

how do epithelia pump water

Answer 12

aquaporins, using passive diffusion

Question 13

CFTR

Answer 13

cystic fibrosis transmembrane conductance regulator

Question 14

CFTR main role

Answer 14

secretes chloride in intestine

Question 15

CFTR direction

Answer 15

2 Cl- in, 1 Cl- out
Na+ follows Cl- out to balances out charge

Question 16

diarrhea is caused by

Answer 16

bacterial enterotoxins
EX: V. cholerae, E. coli, Yersinia, Salmonella

Question 17

Cholera

Answer 17

worldwide pandemic
bacteria spread through contaminated water supplies

Question 18

Toxigenic E. coli

Answer 18

proliferate in institutional settings and infect travelers abroad
promoted by two secretion-stimulating enterotoxins:
1. heat-labile
2. heat-stable

Question 19

heat-labile enterotoxin

Answer 19

similar to Cholera toxin
activates cAMP production

Question 20

heat-stable enterotoxin

Answer 20

STa
activates cGMP production

Question 21

treatment for acute diarrhea

Answer 21

oral rehydration (cheaper and simpler than IV rehydration)
during diarrhea, Cl- leaves, so Na+ can’t enter
TREATMENT: sodium + glucose + water
glucose drags Na+ into body (by SGLT symport)

Question 22

PGC

Answer 22

membrane-bound protein kinase G

Question 23

GC

Answer 23

guanylate cyclase

Question 24

guanylin

Answer 24

mammalian homolog of STa
physiologic agonist for STa-sensitive GC
stimulates HCO3- rich secretion in duodenum

Question 25

cystic fibrosis characteristic symptom

Answer 25

salty sweat

Question 26

cystic fibrosis exocrine gland secretion

Answer 26

1. NaCl + H2O secretion in gland 2. NaCl reabsorption along the duct 3. Hypotonic sweat (normal) [NaCl] < 60 mM

Question 27

placental nutrient transport

Answer 27

changes directly contribute to altered fetal growth

Question 28

altered fetal growth

Answer 28

1. risk factor for complications in perinatal period 2. main cause of cardiovascular disease, obesity, and diabetes in adult life

Question 29

fetal growth is largely determined by...

Answer 29

nutrient supply

Question 30

placental nutrient transporters are specifically regulated in BOTH...

Answer 30

intrauterine growth restriction (IUGR) and fetal overgrowth

Question 31

reduced blood flow highly influences...

Answer 31

highly permeable molecules (EX: O2 and CO2)

Question 32

human placenta expresses

Answer 32

more than 20 different amino acid transporters