Action Potential Flashcards
Why is a refractory period important?
Prevents backflow of action potentials
What threshold must be met for an action potential to commence?
-55mv
What is the resting potential of a cell?
-70mv
When the threshold is met what opens?
Sodium voltage-gated
Na moves down it’s electrochemical gradient
Where does Na move and when in an action potential?
Moves into the cell during depolarisation
When an action potential is met what happens?
Na voltage-gates close
K voltage-gates open
What is the role of calcium?
When the cell reaches + inside Ca2+ channels open. Calcium moves into the cell
Causes release of neurotransmitter
Binds to ligated sodium channels on post synaptic neuron
Whole process then repeated
What is exchanged in the Na+/K+ pump?
2 K+ in
3 Na+ out
What is the absolute refractory period?
Overlaps depolarisation and around 2/3 of depolarisation
New action potential can NOT be generated
- voltage gated sodium channels already open
- sodium channels inactive in depolarisation
Ends when sodium channels recover from inactive state
What is the reflective refractory period?
New generation of action potential is possible
Period overlaps 1/3 of depolarisation
Where does K+ move in repolarisation?
Out of the cell
Where does Na+ move during depolarisation?
Inside the cell
Why is there hyper polarisation and what establishes the resting state?
Due to k+ pumps staying open little bit longer
Sodium potassium pump reestablishes resting state
