Lec 29

Question 1

Action potential is

Answer 1

The voltage across a membrane

Question 2

Resting membrane

Answer 2

-70mV

Negative inside

Question 3

Ions important for action potential

Answer 3

Na+ and K+

Cl-

Question 4

Resting is maintained by

Answer 4

Sodium potassium pumps (3 sodium out, 2 potassium in )

Potassium leak channel (open randomly allowing potassium to leave)

Question 5

Ion channel shape

Answer 5

Channel

Question 6

Potassium channels are

Answer 6

Homotetramers

4 subunits with a pore in the middle

Question 7

Sodium channels are

Answer 7

Monomers with 4 domains

Question 8

Sodium and potassium channels classification

Answer 8

Passive

Uniport

Gated

Question 9

Both channels are

Answer 9

Voltage gated

When the potential is -40mV, they open

Has winglike channels keeping it closed that open when the inside is more positive than the outside

Question 10

Sodium channels open

Answer 10

Quicker

Question 11

Sodium channels are also

Answer 11

Channel inactivated

Can either be open or inactive (protein that wants to move negative charge in the outside blocks the channel)

Question 12

Potassium are only

Answer 12

Voltage gated

Open or closed

Question 13

Na + channels go from

Answer 13

Closed to open to inactive and then back to closed

Question 14

Voltage gated channels allow for the transport of

Answer 14

Many ions

Pumps and channels only allow few

Question 15

Depolarizing phase

Answer 15

Once membrane potential passes -40 mV, all Na+ channels open

Goes to +40 mV

Question 16

Repolarizing phase

Answer 16

Na+ channels inactivate

K+ channels open

Which drives the membrane potential back down

Question 17

Refractory period

Answer 17

Na+ channels inactive

K+ channels open

Question 18

Ready for new action potential

Answer 18

After membrane is below -40mV for a time

Na+ and K+ channels close

Question 19

How a action potential travels in a typical neuron

Answer 19

Many action potentials happen along the axon in a localized region

They spread along the axon

Question 20

Action potential speed

Answer 20

5 m/sec

Question 21

Does the action potential lose strength as it travels

Answer 21

No

Question 22

Injecting Na+ into the middle of the axon

Answer 22

An action potential would travel in both directions

Question 23

Giant axons

Answer 23

Found in invertebrates

Larger diameter leads to quicker action potentials

Question 24

Vertebrate method of speeding up action potentials

Answer 24

Glial cells wrap a neuron with myelin

Action potential hops between gaps