Action potentials: generation and transmission Flashcards
What causes the potential inside a cell to change
a cells potential is not constant.
it changes its permeability or ion conc changes
What is hyperpolarisation
cell becomes more negative -70 to -75.
Potential within the cell moves closer to Ek and Ena
What is depolarisation
cell is less negative
-70 to 60.
potential inside the cell moves away from Ek and closer to Ena
When do action potentials occur
occurs when voltage reaches a threshold (-55)
occurs due to a short opening of the voltage gated ion channels
What is stage 1-2 in action potentials
absolute refractory period
what is stage 3 in action potential
relative refractory period
What is the first stage in action potentials
a slow depolarization due to stimulus
what is the second stage in action potential
after threshold is reached fast depolarization occurs
what is the third stage in action potential
repolarization
what is the fourth stage of action potentials
after hyperpolarisation
Describe stage 2: Fast deploarisation: action potential mechanisms
once threshold is met their is a sudden activation of voltage gated Na ion channels
Describe stage 3 replarisation: action potential mechnisms
inactivation of Na ions and activation of K= channels
What causes the Na channel to slow down and stop
increase in Na ion causes the inside to become more positive
Na attraction is less
Na channels inactivate
Describe the amplitude of action potentials
usually constant
What kind of energy is generated when the current is generate outside of the source
(outside to inside)
Hyperpolarisation
MP becomes more negative
