Excitable Membranes

Question 1

2 initial conditions required for electrical activity

Answer 1

1. Selectively permeable cell membrane

2. Difference in concentration across the membrane of electrically charged ions in solution

Question 2

2 classes of transport proteins

Answer 2

Carrier proteins

Channel proteins

Question 3

Concentration INSIDE the cell of

1. Na
2. K

Answer 3

1. 15 mM (low)

2. 150 mM (high)

Question 4

Concentration OUTSIDE the cell of

1. Na
2. K

Answer 4

1. 150 mM (high)

2. 5 mM (low)

Question 5

Na/K ATPase moves…

Answer 5

3 Na out

2 K in

Question 6

K+ equ potential value is…

Answer 6

-90mV

Question 7

Na+ equ potential value is…

Answer 7

+60mV

Question 8

Resting membrane potential value is…

Answer 8

-70mV

Question 9

Activation and inactivation gate, open or closed? (Na channel)

1. Resting state
2. Rising phase
3. Falling phase
4. Afterhyperpolarization

Answer 9

1. Activation closed, inactivation open
2. Both open
3. Inactivation gate closed, activation open
4. Both closed

Question 10

Electrotonus

Answer 10

How electrical events propagate

Question 11

Electrotonic decay

Answer 11

Charge leaking outward of a cell

From current travelling along the axon

Question 12

Active propagation

Answer 12

Regenerative process

APs activate voltage-gated channels along the axonal membrane to regenerate depolarization

Question 13

Which two cells myelinate nerves and where?

Answer 13

Schwann cells in the PNS

Oligodendrocytes in the CNS

Question 14

Basic function of myelin is to reduce ____

Answer 14

the amount of membrane capacitance