Unit 6 Resting Potential & Action Potential Flashcards
What’s the resting potential
Axon not conducting an impulse
Explain the events happening in Resting Potential
The resting potential is maintained by the SODIUM-POTASSIUM PUMP (involves active transport +ATP)
- transports sodium ions from the neurone to outside
- transports potassium ions from outside to neurone
What’s an action potential and what are the 5 stages of it
Generate impulses when the threshold value is reached (-55mV)
Depolarisation
Repolarisation
Hyperpolarisation
Restoring resting potential
What is depolarisation
When the sodium channels open so sodium ions diffuse into the axon
- Negatively charged to positively charged
- reaches +40mV then the Na gates close
What’s is repolarisation
- voltage gated Na+ channels close
- voltage gated K+ channels open
- K+ ions diffuse out of the axon
What’s is hyperpolarisation
- No net movement of ions
- K+ channels stay open for long time
- then shut slowly this causes more K+ to diffusion out
What’s restoration of the resting potential
The Na+/ K+ ATPase pump active so resting potential restored
Explain the All or Nothing response and why it’s important
All- means the same size of action potential
Nothing- means if no threshold value reached no action potential
It’s important because it allows animals to only respond to large enough stimuli
What is the refractory period
- impulses are discrete
- impulses can only travel in one direction- this allows response as 2 directions would prevent response
- limits the number of impulse transmission(action potential)- this prevents over reaction
What are the factors affecting the speed of conduce
- myelination causes the action potential to jump from one node to another(saltatory conduction) this speeds up impulses
- axon diameter- bigger diameter causes less resistance to the flow of ions
- temperature - faster nerve impulses (temp affects diffusion of ions)
