Ch. 3 Module 2

Question 1

what is the fluid that neurons are bathed in?

Answer 1

extracellular fluid

Question 2

What are the two types of ion channels:

Answer 2

1. Non gated - are continually open and offer no resistance to the passage of ions
2. gated - can close and prevent the flow of ions

Question 3

What are the two types of gated channels?

Answer 3

1. Voltage gated channel
2. chemically gated channel.

Question 4

Voltage gate channel:

Answer 4

open when there is an electrical current (stream of ions)

Question 5

Chemically gated channel:

Answer 5

will only open when a specific type of molecule binds to a binding site on the channel molecule

Question 6

How is charge generated?

Answer 6

Resting potential & action potential

Question 7

What are the two factors that resting potential depends on?

Answer 7

Ion distributions or concentrations, inside and outside the membrane, and the state of the gates on the ion channels

Question 8

What are the two forces that cause ions in a solution to move?

Answer 8

1. Diffusion
2. electrostatic force

Question 9

Diffusion

Answer 9

ions move from an area with high concentration to an area of low concentration (no energy is needed)

Question 10

electrostatic force

Answer 10

ions move due to their electrical charge
- opposite charges attract each other
- like charges repel each other
(no energy is needed)

Question 11

What does DNP do?

Answer 11

it is a metabolic inhibitor

Question 12

the Sodium potassium pump

Answer 12

• pumps 3 sodium out of the cell and brings in 2 potassium ions during each cycle
• because it removes 3 positive ions and replaces only two inside the membrane, every cycle makes the inside more negative by one ion
• the pump is electrogenic

Question 13

Where is TTX obtained from?

Answer 13

Puffer fish

Question 14

What does TTX do?

Answer 14

• blocks sodium channels, but has no effect on potassium channels.
• allows researchers to study how the membrane changes when only potassium channels are open

Question 15

What are the properties of Na+ channels?

Answer 15

• 2 gating mechanism
• activation gate opens
• Na+ flows briefly
• inactivation gate closes

Question 16

What are the properties of voltage gated K+ channels?

Answer 16

• delayed in opening
• one gating mechanism
• it won’t open until the sodium channel has opened and closed

Question 17

What happens when K+ ions leave?

Answer 17

membrane potential will hyperpolarize

Question 18

Na+ channel opening produces what?

Answer 18

Depolarization

Question 19

absolute refractory period

Answer 19

fixed period of time when the ball and chain gate closes before sodium channels can rest and the hinge gate can open again.

Question 20

relative refractory period

Answer 20

time it takes until resting potential is re-established

Question 21

how is the action potential generated?

Answer 21

initiated when the voltage gated sodium channels open and sodium rushes into the cell. if the threshold is reached, all remaining sodium channels in the area open and the rapid depolarization known as an action potential occurs.