Lecture 5

Question 1

apical membrane

Answer 1

with microvilli faces the lumen

Question 2

basolateral membrane

Answer 2

faces the ecf

Question 3

What ensures one-way movement transporting epithelia?

Answer 3

polarized distribution of membrane transporters

Question 4

the body as a whole is…..

Answer 4

electrically neutrAL

Question 5

major cations

Answer 5

intracellular K+ and extracellular Na+

Question 6

major anions

Answer 6

intracellular phosphate ions and extracellular chloride ions

Question 7

the ECF has a slight excess of…..

Answer 7

cations

Question 8

the ICF has a slight excess of ….

Answer 8

anions

Question 9

law of conservation of electrical charge

Answer 9

net amount of charge produced in any process is zero

Question 10

separating positive and negative charges….

Answer 10

require energy

Question 11

conductor

Answer 11

material through which positive and negative charges can move towards one another (water)

Question 12

insulator

Answer 12

material separating charges (membrane)

Question 13

membrane potential

Answer 13

the electrical disequilibrium that exists between the ECF and ICF

Question 14

equilibrium potential

Answer 14

the membrane potential that exactly opposes the conc. gradient

Question 15

nernst equation

Answer 15

used to calculate the equilibrium potential

Question 16

resting membrane potential

Answer 16

the membrane potential of a cell when it is not active

Question 17

relative scale of electrical gradient for excitable cells

Answer 17

-40 to -90 mV

Question 18

the resting membrane potential is due mostly to…

Answer 18

K+

Question 19

resting cells are permeable to…

Answer 19

both Na+ and K+ to different degrees

Question 20

cell membrane is about ….. more permeable to K+

Answer 20

40

Question 21

What maintains concentration gradients for Na+ and K+?

Answer 21

Na-K ATPase

Question 22

What factors influence a cell’s membrane potential?

Answer 22

• conc gradient (uneven distribution) of different ions across the membrane
• permeability of membrane to those ions

Question 23

depolarization

Answer 23

if membrane potential becomes less negative than resting

Question 24

repolarization

Answer 24

return from depolarization

Question 25

hyperpolarization

Answer 25

membrane potential becomes more negative