1/26: Cell Membrane, Membrane Transport, and Membrane Potential VI

Question 1

What direction will Na+ move down its EC gradient?

Answer 1

Into the cell

Question 2

What does depolarization mean?

Answer 2

Vm becomes less negative than rest

Question 3

What does repolarization mean?

Answer 3

Vm change that restores resting Vm

Question 4

What direction will K+ move down its EC gradient?

Answer 4

Out of the cell

Question 5

What happens to Vm as K+ moves?

Answer 5

Hyperpolarizes

Question 6

What does hyperpolarization mean?

Answer 6

Vm becomes more negative than rest

Question 7

What does repolarization mean?

Answer 7

Vm change that restores resting Vm

Question 8

What are Vm changes defined by?

Answer 8

Their initial change in Vm

Question 9

What are examples of ions that cause a depolarization?

Answer 9

Na+
Ca2+

Question 10

What are examples of ions that cause hyperpolarizaiton?

Answer 10

K+
Cl-

Question 11

Answer 11

Question 12

When an ion moves down EC gradient, Vm moves towards _______, _______ the EC gradient for ion movement and subsequently _______ rate of ion movement via __________

Answer 12

Eion; decreasing; decreasing; facilitated diffusion

Question 13

What are two determinants of resting membrane potential?

Answer 13

1. Relative ion permeabilities
2. Na+/K+ ATPase activity

Question 14

What does Na+/K+ ATPase do?

Answer 14

1. Maintains concentration gradient for Na+ and K+
2. Pumps 3 Na+ out and 2+ K in

Question 15

What are two things that can be done to change the membrane potential

Answer 15

1. Change the membrane’s permeability to an ion (open/close a channel, or change activity of an active transporter)
2. Change the ion concentration gradient across the membrane

Question 16

Ex: hyperkalemia (an increase in blood K+ concentration)
When K+ concentration outside of the cell is increased, the force of the concentration gradient is ________

Answer 16

Lessened

Question 17

ex: hyperkalemia (an increase in blood K+ concentration)
Less K+ exits cell down the electrical gradient and the membrane therefore __________

Answer 17

Depolarizes

Question 18

In normokalemia, where is the K+ in relation to the -70mV?

Answer 18

Stimulus is aligned with -70mV

Question 19

In hyperkalemia, where is the K+ in relation to the -70mV?

Answer 19

Stimulus is above -70mV

Question 20

In hypokalemia, where is the K+ in relation to the -70mV?

Answer 20

Stimulus is below -70mV