15.2 - Nervous Impulse Flashcards
Setting up the resting potential Generation of an action potential The all-or-nothing principle
What is the resting potential?
The specific number and a definition
- Voltage difference across neurone membrane when not transmitting signals
- around -70 mV
What is the typical resting potential?
-70 mV
What maintains the resting potential?
- Sodium-potassium pumps
- Potassium ion channels
- Sodium ion channels
What is the role of sodium-potassium pumps?
Move 3 Na+ out
What is the role of potassium ion channels?
Allow K+ diffusion out
What is the role of sodium ion channels during resting potential?
Closed
What happens during an action potential?
Inside of axon becomes positively charged
What are the stages of an action potential?
Resting potential
What happens during depolarisation?
Na+ channels open
What is the threshold potential?
-55 mV
What happens during repolarisation?
Na+ channels close
What happens during hyperpolarisation?
Excess K+ leaves
What is the refractory period?
Ion pumps restore resting potential
What is the all-or-nothing principle?
Action potential triggered or not triggered
What is the threshold phenomenon?
Action potential always triggered if threshold reached
What is the effect of a stronger stimulus?
Increased frequency of action potentials
