Lec 4

Question 1

Where are post-synaptic potentials integrated

Answer 1

At the axon hillock

Question 2

Squid Giant axon

Answer 2

The size of the giant axon allowed the use of microelectrodes to be used effectively to stimulate and record

Question 3

What would stimulating an axon do?

Answer 3

Release an action potential

Question 4

What is important for the peak of an action potential

Answer 4

Sodium levels

Question 5

Phase 1 of an action potential

Answer 5

Depolarization

Question 6

Phase 2 of an action potential

Answer 6

Repolarization

Question 7

Phase 3 of an action potential

Answer 7

Hyperpolarization

Question 8

Increased permeability to what during the rising phase

Answer 8

Sodium

Question 9

Increased permeability to what during falling phase

Answer 9

Potassium

Question 10

absolute refractory period

Answer 10

Cell is incapable of generating a new action potential

Question 11

Relative refractory period

Answer 11

More difficult to generate a new action potential

Question 12

Voltage Clamp experiments found

Answer 12

Early inward Na+ current followed by later outward K+ current

Question 13

What blocks the outward K+ current

Answer 13

Tetraethylammonium (TEA)

Question 14

What blocks the inward Na+ current

Answer 14

Tetrodotoxin (TTX) and Saxitoxin (STX)

Question 15

Structure of the Na+ channel

Answer 15

-Consists of an alpha and 2 beta subunits

alpha has 4 separate domains (D1-DIV)

Each domain has 6 helical segments (S1-S6)

S4 is charged, and is the voltage sensor to open the activation gate

IFM-the inactivation gate

Question 16

Structure of the Ca+ channel

Answer 16

1 alpha and 2 beta subunits

alpha has 4 separate domains (D1-DIV)

Each domain has 6 helical segments (S1-S6)

S4 is charged, and is the voltage sensor to open the activation gate

IFM-the inactivation gate

Question 17

K+ channel structure

Answer 17

1 alpha and 2 beta subunits

alpha has 4 separate domains (D1-DIV)

Each domain has 6 helical segments (S1-S6)

S4 is charged, and is the voltage sensor to open the activation gate

IFM-the inactivation gate

All four domains are identical

Question 18

VSD-Voltage sensitive domain

Answer 18

S1-S4

Question 19

P-Loop

Answer 19

Between S5 and S6

Determine ion selectivity

Question 20

Pore domain

Answer 20

S5,S6

Question 21

Where is the IFM

Answer 21

After S6 (last part)

Question 22

What kind of changes do ion channels undergo when channels are opening, closing and inavtivating

Answer 22

Conformational changes