The Action Potential Flashcards
What is the characteristic profile of action potentials
Properties of voltage gated Na and K channels
how to neurons use electrical signals?
In the forms of action potentials to communicate with each other
How is the communication between neurons done
By propagation of an electrical signal and release of neurotransmitters
At rest, the cell membrane is much more permeable to which ion?
K+
- is the main ion the contributes to the RMP value
At rest, which ion is the cell membrane slightly permeable to?
Na+
What controls permeability of a neuron
gated channels
What do mechanically gated ion channels do
Open in response to mechanical stimulation
What do chemically gated ion channel do
Open in response to a chemical binding
What do voltage-gated channels do
Open in response to a voltage change
Difference between Na+ and K+ voltage gated channels
Na+ is faster to open where as K+ channel is lazy and slow to close
What is depolariztiton
Cell becomes more positive
What is repolarization
The depolarized membrane returns to RMP
What is the threshold
The minimum depolarization that will initiate an action potential
-55mV
What is hyperpolarization
Cell becomes more negative
Where to graded potentials occur
neuron dentrites
How do graded potential occur
Either depolarization or hyper polarization caused by opening voltage gated channels
What is a graded potential proportional to
Amplitude of potential is directly proportional to the stimulus strength
What are the 2 reasons why graded potentials can only travel a short distance and lose strength over time
- Current leak
2. Cytoplasmic resistance
In what part of the neuron does the stimulus have to reach in order to generate an action potential
axon hillock with at least -55mV
What are the 3 important things about action potentials
- All or none
- Unidirectional
- Always same amplitude and duration
What is the absolute refractory period
When a a depolarized cell is returning back to the RMP, no action potentials can be generated until the channels are back to their resting position
Which gate is responsible for the absolute refractory period
Inactivation gate
What is the loss of K+ through the potassium channel responsible for?
hyper polarization of the cell
-action potentials can be generated here but has to be a strong enough stimulus to push it over the threshold
