2.6 Lundy Ch. 2 (1)

Question 1

When does an electrical potential across a membrane exist?

Answer 1

difference in ion distribution creates a difference in charge on either side

Question 2

4 types of membrane channels

Answer 2

• leak channels
• modality gated channels
• ligand gated channels
• voltage gated channels

Question 3

leak channels

Answer 3

allow diffusion of a small number of ions at a slow rate

Question 4

gated channels

Answer 4

• open in response to a stimulus

- close when stimulus is removed

Question 5

modality gated channels

Answer 5

• specific to sensory neurons

- open in response to mechanical forces, temperature changes, or chemicals

Question 6

ligand gated channels

Answer 6

open in response to a neurotransmitter binding to a receptor on a postsynaptic membrane

Question 7

What does the opening of ligand gated channels produce and how?

Answer 7

• generates local potentials

- allow ions to flow back and forth

Question 8

voltage gated channels

Answer 8

• open in response to changes in electrical potential across membrane
• open and close very quickly
• form action potentials

Question 9

electrical potential

Answer 9

difference in electrical charge carried by ions

Question 10

3 types of electrical potentials

Answer 10

• resting membrane potential
• local potential
• action potential

Question 11

What is RMP?

Answer 11

• value of electrical potential across the membrane when a neuron is not transmitting information
• steady state
• no net ion flow

Question 12

two forces that act on ions to determine distribution across plasma membrane

Answer 12

• concentration gradient

- electrical gradient

Question 13

concentration gradient

Answer 13

ions flow from high to low concentrations

Question 14

electrical gradient

Answer 14

only a certain number of ions flow across due to concentration of charges

Question 15

equilibrium

Answer 15

• equal ion movement across the membrane

- maintains same net charge

Question 16

RMP value

Answer 16

-70 mV

**means the inside of the neuron has more negative charges than the outside

Question 17

What maintains the -70 mV RMP in a neuron?

Answer 17

• anions trapped inside the neurons (too large to diffuse)
• passive diffusion through leak channels
• Na/K pump

Question 18

Na/K pump

Answer 18

uses ATP to move ions against electrochemical gradient

Question 19

Na/K pump: how many of each does it transport?

Answer 19

2 K+ ions into the cell

3 Na+ ions out of the cell