CTR - 7 - AP Flashcards
What is depolarisation?
A decrease in potential difference between the inside and outside of the cell. (inside less negative than RMP)
What is hyperpolarisation?
An increase in potential difference between the inside and outside of the cell. (inside more negative than RMP)
What is repolarisation?
Return to RMP from either direction
What is overshoot
When the inside of the cell becomes positive due to reversal of membrane potential polarity
What is this? A decrease in potential difference between the inside and outside of the cell.
Depolarisation
What is this? An increase in potential difference between the inside and outside of the cell.
Hyperpolarisation
What is this? Return to RMP from either direction
Repolarisation
What is this? When the inside of the cell becomes positive due to reversal of membrane potential polarity
Overshoot
What cells are excitable cells?
Muscle and nerve cells
What are excitable cells?
Allow an action potential to propagate along it
What are the two ways a change in membrane potential can be achieved?
1 - altered membrane ion permeability
2 - anything that alters ion concentrations on either side
What are the two types of potentials?
Graded potentials (sub threshold potentials)
Action potentials
How is a GP/AP generated (in broad terms)?
Increase in Na+ permeability –> sodium moves into cell –> if this reaches the threshold potential –> depolarise the cell
A _________ stimuli causes _________ potentials.
subthreshold stimuli –> sub threshold/graded potentials
suprathreshold stimuli –> APs
What is the threshold which must be reached?
-50 mV
The strength of a GP is proportional to the ________.
strength of the stimulus
The_________ is proportional to the stimulus strength.
GP strength
What happens to GP strength? Why?
Loses strength moving through the cell
Due to leakage of charge across membrane