Action potential

Question 1

Diffusion

Answer 1

• moving along concentration gradients
• increasing temp and no. of molecules increases diffusion
• passive
• equilibrium must be found
• semipermeable membrane

Question 2

ion

Answer 2

Molecule or atom with net negative or positive electrical charge

Question 3

K+

Answer 3

Potassium

Question 4

Na+

Answer 4

Sodium

Question 5

Sodium/potassium pump

Answer 5

• Active transport mechanism requiring extra energy to do its work
• 3 sodium out, 2 potassium in with every cycle making cell more negative

Question 6

Resting membrane potential:

Answer 6

-70mv

Question 7

polar definition:

Answer 7

inside= negative
outside= positive

Question 8

T/F- action potentials are all or nothing

Answer 8

True

Question 9

where do action potentials occur?

Answer 9

axon

Question 10

What are the 3 stages of an action potential and their membrane potentials?

Answer 10

Depolarization= 30mv
Repolarization= -85mv
hyperpolarization= -70mv

Question 11

What are the 2 refractory periods?

Answer 11

Absolute- action potential cannot occur until the last is over (before hyperpolarization)
Relative- a 2nd AP can occur during a very strong stimulus (after repolarization)

Question 12

What is the AP threshold?

Answer 12

-55mv

Question 13

Schwann cells

Answer 13

Glial cells of PNS

Question 14

purpose of myelin sheath?

Answer 14

Allows faster conduction of action potentials, where they only occur in the nodes of ranvier

Question 15

What are compound AP’s?

Answer 15

Action potentials that can add together to get larger in a single neuron

Question 16

3 ways of signal termination:

Answer 16

1. reuptake/reuse
2. neurotransmitter inactivation by enzymes
3. diffuses away from synaptic cleft

Question 17

What are graded potentials?

Answer 17

Small changes in the cell that can cause AP’s if at -55mv

• depends on size of stimulus
• occurs in dendrite or cell body