15.2 The Nerve Impulse Flashcards
What is the generator potential?
Change in potential difference caused by a stimulus
What is the resting potential?
The difference in electrical charge maintained across the membrane of the axon of a neurone when not stimulated
What is the action potential?
The change that occurs in the electrical charge across the membrane of an axon when it is stimulated and a nerve impulses passes
How can Na+ and K+ be controlled by the axon membrane?
- phospholipid bilayer prevents K+ and Na+ diffusing across it
- gated channel proteins allow Na+ and K+ by facilitated diffusion
- sodium- potassium pump actively transports K+ and Na+
How is the resting potential established inside of the axon?
- active transport of 3Na+ out
- active transport of 2K+ in
- K+ diffuses out faster than Na+ can diffuse in
How is an action potential generated?
- Na+ channels open
- allowing rapid influx of Na+
How is an axon membrane repolarised?
- Na+ channels close
- K+ channels open
- allowing efflux of K+
How is hyperpolarisation of the axon formed?
Overshoot of the electrical gradient by the efflux of K+ by facilitated diffusion
What has happened when the axon has said to have been repolarised?
The resting potential has been re-established
How does the influx of Na+ get into the axon?
By facilitated diffusion through the sodium voltage- gated channels
How does the efflux of K+ get out of the axon?
By facilitated diffusion through potassium voltage- gated channels
Draw the action potential graph
Page 352
What is the threshold level/ threshold potential?
Potential needed for depolarisation of the axon
What is the size of the generator potential if there is a slight stimulus?
Small generator potential
What is the size of the generator potential if there is a large stimulus?
Larger generator potential
