ELM7: The action potential Flashcards
What are classes as excitable cells?
Pain sensors
Neurones
Photoreceptors
What is the function of excitable cells
Allow sensing and response to environment
Communicate during action potentials
What is meant by action potentials being all or nothing events?
If depolarised there won’t be an event unless threshold potential is reached
In what ways can action potential depending on the tissue?
Shape
Duration
What is a positive feedback loop?
Depolarisation causes channel opening and influx of ions
Ion influx causes further depolarisation
What occurs when potassium channels open due to depolarisation?
Influx of ions causes repolarisation
Fewer potassium channels are open
What is the refractory period?
Period after action potential where you can’t stimulate as easily
What are the two components of refractory periods?
Absolute refractory period
Relative refractory period
What is the absolute refractory period
Where you can’t produce another AP
What is the relative refractory period?
Cell is less excitable and can be stimulated with a larger stimulus
What causes the refractory period?
Inactivation of sodium current
Activation of potassium current
What are the symptoms of Dravet syndrome?
Seizures provoked by high temperatures
Motor problems Cognitive issues
What is the cause of Dravet syndrome?
Mutation in SCN1A gene which codes for sodium channel Na1.1
Prevents action potentials in inhibitory neurons
Lack of inhibition in some parts of brain
What is a treatment of dravet syndrome?
Cannabidiol
What is the duration of cardiac action potentials?
200ms
