Ionic basis of membrane potentials (Nernst)

Question 1

Tell me 4 properties of neurones?

Answer 1

1. Excitability
2. Integration/ filtering and propagation of signals e.g action potential propagation
3. Transmission of signals
4. Plasticitiy

Question 2

What does the plasticity of a neurone mean?

Answer 2

Its looking at changes in synaptic strength and sensitivity of neurones with incoming signals

Question 3

Tell me how the charge varies in and out in a giant squid axon?

Answer 3

The inside of the axon is negative with respect to the outside

Question 4

What three ways maintain the potential gradient in the axon?

Answer 4

1. The difference in ion concentration between inside and outside of the axon
2. the selective permeability of the membrane to K+
3. Ion pumps that help to maintain gradients

Question 5

This table shows the difference in ion concentration in and out of the axon

Answer 5

Question 6

Tell me about the selective permeability of the membrane to k+ and the ratio of ions moving in/out and what required in order for this to occur?

Answer 6

3 Na+ out of the cell

2K+ into the cell

ATP needs to be hydrolysed to ADP + Pi by the ATPase of the transporter

NaK ATPase transports the sodium and potassium in each cycle

Question 7

Whats the name of the ion pump that helps to maintain the electrochemical gradient?

Answer 7

The Na+/K+ ATPase pump

Question 8

Because the sodium-potassium pump is electrogenic, what can block it?

Answer 8

Ouabain

Question 9

What type of transport is used to transport Na+ and K+ down their concentration gradients?

Answer 9

Facilitated diffusion

Question 10

Whats the Nernst equation formula and what does each component represent?

Answer 10

Question 11

What is the Nernst equation used to do?

Answer 11

Compare the electrical and concentration gradients

It helps to determine the direction of ion movement at any given membrane potential

in effect, this converts chemical gradient to an electrical gradient

Question 12

Do more questions of the Nernst equation but this is an example of it simplified…

Answer 12

Question 13

Whats the Goldmann constant field equation (basically an extended version of the Nernst equation)

Answer 13

Question 14

Draw a basic action potential graph and include the RMP and peam amplitude

Answer 14

Question 15

Draw out a diagram that represents the fast rising phase of an action potential

What type of feedback loop is it?

Types of channels opening etc.

Answer 15