Graph of 15.2 Flashcards Preview

A-level Biology: Chapter 15 - Nerve Impulses > Graph of 15.2 > Flashcards

Flashcards in Graph of 15.2 Deck (20)
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1
Q

What happens at 1?

A

Na+ ions/K+ ion pump active maintaining resting potential

2
Q

What happens at 2?

A

Stimulus causes some Na+ ions channels to open allowing some Na+ ions into the axon

3
Q

What happening at 3?

A

Resting potential of -70mV When no impulse

4
Q

What happening at 4?

A

Membrane potential is less negative as Na+ ions diffuse through the axon

(-55mV threshold reached)

5
Q

What happening at 5?

A

All Na+ ion channels open - rapid influex (IN) of Na+ ions

6
Q

What is happening at 6?

A

All Na+ ion channels close at +40mV

7
Q

What happening at 7?

A

All K+ ion channels open

8
Q

What is happening at 8?

A

Rapid eff;ux (OUT) of K+ ions = electricla charge inside axon falls as K+ ions move out so axon membrane starts to be repolarised back to the original -70mV

9
Q

What is happening at 9?

A

K+ ion channels remai open = hyper polarisation

10
Q

What is happening at 10?

A

K+ ion channels clse at -80mV/90mV

11
Q

What is happening at 11?

A

Na/K ion pump now allow membrane potential to go from hyper-polarised back to resting potential of -70mV

12
Q

What is happening at 12?

A

Resting potential is re-estbalished at -70mV

13
Q

Explain the shape of the curve for sodium ions between 0.5 ms and 0.7 ms

A

Sodium channel protein close

Sodium ions move into the axon membrane by faciliated diffusion (depolarisation)

More sodium channels are open

Makes inside of axon less negative

14
Q

During an action potential, the membrane potnetial rises to + 40mV and then falls

Use this information to explain the fall in membrane potential

A

Potassium channels open

Sodium channel protein close

Potassium ions move out of axon membrane by facilitated diffusion (repolarising)

Making axon membrane change from +ve to -ve

15
Q

After exercise,

some ATP is used to re-estbalish the resting potential in axons

Explain how the resting potential is re-established

A

Resting potential is re-established

Active transport is used to pump 3Na+ out of the axon membrane and pump 2K+ in the axon membrane using sodium-potassium pump

16
Q

Protein C requires ATP to function

Describe the function of C

A

C is the sodium-potassiium pump

It requires ATP for active transpirt to move 3Na+ ions out of the membrane and 2k+ in the membrane

This helps to restore resting potential

Restores ion balance after an action potential

Transport sodium and potassium ions

17
Q

The plasma membrane of the neurone is more permeable to the potassium ions than the sodium ions

Give the evidence from diagram that supports this

A

Fewer protein B molecules to transport sodium ions

18
Q

Describe how the resting potential is re-established in an axon by the movement of ions across the membrane

A

Pump 3Na+ ions out of the axon membrane while 2K+ pump in using sodium-potassium pump by active transpirt

Some diffusion of K+ out of thr axon (more channel proteins of K+ than Na+)

19
Q

Sodium and potassium ions can only cross the axon membrane through porteins

Explain why

A

Can not pass through the phospholipid bilayer

Because water soluble and not lipid soluble

Charged

Hydrophillic

20
Q

Protein A and B differ from each other

Explain why different proteins are required for the diffusion of ions through membrane

A

Different proteins have different specific tetirary structure

Ions have different sizes/shapes