Lesson 6

Question 1

RMP is set by ____ trying to pull Vm towards their equilibrium ornteisl

Answer 1

Different ion gradients

Question 2

At rest, which gradient and equilibrium constant wins?

Answer 2

K+ and Ek because it has a larger conductance (Gk»GNa)

Question 3

The cell membrane is packed with which type of leak channels?

Answer 3

Leak K+ channels

Question 4

Capacitors take up ___ but cannot generate their own

Answer 4

Voltage

Question 5

Why are Ek and Ena considered voltage sources?

Answer 5

Because they can deposit charges onto inner and outer leaflets of membrane

Question 6

Additions of more positive charges by Ena battery to INSIDE of membrane makes the Vm (positive/negative)

Answer 6

Positive and DEPOLARIZES the cell

Question 7

Additions of positive charges by EK battery to OUTSIDE of membrane makes the Vm (positive/negative)

Answer 7

Negative and HYPERPOLARIZES the cell

Question 8

When does the Ena battery stop charging?

Answer 8

When Vm = Ena

Question 9

What is an RC circuit?

Answer 9

Circuit made up of resistors and capacitors and a battery

Question 10

The GHK equation can be used to conceptualize what happens during what process?

Answer 10

Cellular excitation as changes in Gna and Gk occur when different channels open and close

Question 11

What are two reasons why GHK equations dont work to explain cellular excitation

Answer 11

1. GHK does not work when there are fast charges because capacitors like the cell membrane need time to charge
2. Gna and Gk change quickly during an AP

Question 12

Excitatory graded potential result from a rise in what?

Answer 12

Rise in Gna

Question 13

Excitatory graded potential result from a rise in what?

Answer 13

Rise in Gna from synaptic glutamate and acetylcholine receptors/channels

Question 14

Inhibitory graded potential result from a rise in what?

Answer 14

Rise in GCl from synaptic GABA and Glycine receptors

Question 15

Action potentials have a temporary rise in Gna followed by a rise in __

Answer 15

Gk

Question 16

The first triangle in the voltage clamp reads what?

Answer 16

Membrane voltage (Vm)

Question 17

Command voltage is the voltage you want to ____

Answer 17

Keep the cell at

Question 18

The second triangle (amplifier 2) is needed to balance out the membrane voltage and the ____ voltage

Answer 18

Command voltage

Question 19

If there is a difference between vm and cv then there will be ____ injected into the cell

Answer 19

Current

Question 20

The goal of amplifier B is to

Answer 20

Make sure Vm and Vc are equal

Question 21

The third amplifier (C) measures the current injected by amplifier

Answer 21

2/B

Question 22

Which law can be used to read the current exiting amplifier B?

Answer 22

V=IR

Question 23

Hogkin and Huxley saw three things in their first voltage clamp records?

Answer 23

• A capacitative current (current injected by amplifier B)
• An early current (Na coming into cell)
• A late current (K+ leaving thje cell)

Question 24

Generally as you increase current and amplitude, the Na+ graph will increase but at some point it will reverse directions, when does this happen?

Answer 24

When Vm gets closer to Ek

Question 25

The activation constants for K conductance is:

Answer 25

N4

Question 26

The activation of Na conductace are:

Answer 26

M3H M: activation parameter (tells you how Na channels open) H: inactivation parameter (the falling phase of AP)

Question 27

The four steps defining an AP are:

Answer 27

1. Assuming mild depression. at t=0.01 ms 2. Calculated Gna and Gk at t=0.01 ms 3. Calculated Ina and Ik 4. Calculated change in Vm and added that to V0.01 5. Repeated steps 2-5