Changing Membrane Potential Flashcards
What units are membrane potential measured in
Milivolts
How do you measure membrace potentials
Using a microelectrode to penetrate the cell membrane
What are microelectrodes filled with
A conducting solution such as KCl
What 2 factors are important for the generation of membrane potential
Asymmetric distribution of ions and selective Ion Channels
What is selective permeability
Movement of specific ions across the cell membrane
What can travel though a phospholipid bilayer
Small, uncharged molecules
What does the Nernst equation calculate
The equilibrium potential for an ion
What is the resting potential for cardiac cells
-80mV
What is the resting potential for nerve cells
-70mV
What is the resting potential for smooth muscle cells
-50mV
Why do some cells have lower resting potentials
Lower selectivity for potassium
What is the main driving force behind the negative resting potential
Moment of potassium out of the cell
What is an electrochemical gradient
Combination of electrical and concentration differences to determine the direction of the movement of the ion
What is the resting potential for skeletal muscle
-90mV
Why have some cells got a more negative resting potential
Lots of potassium ions
What is the equilibrium potential
When the electrical and chemical gradients are equal
What is depolarisation
Decrease in size of membrane potential
What is hyperpolarisation
Increase in size of membrane potential
What causes Changes in membrane potential
Changes in ion selectivity
What is conductance
Is how the contribution of each ion to the membrane potential will depend on the ions permeability
What is the GHK equation
Calculates membrane potential from lot of ions
Give an example of a mechanical gated channel
Sound waves cause hairs in the ear to move which opens Ion Channels
What are mechanical Gated channels
Channels that open or close in response to membrane deformation
What sort of channels are used in fast synaptic transmissions
Ion Channels
What do excitatory transmitters cause at synapses
Depolarisation
What do inhibitory transmitters at synapses cause
Hyperpolarisation
Give 2 examples of excitatory neurotransmitters
ACh and dopamine
What is summation
When the amount of excitable or inhibitory transmitters exceeds the other to give an overall response
What 2 types of transmitters are released in fast synaptic transmission
Excitatory and inhibitory
What type of receptor is used in slo synaptic transmission
GPCRs
How much does the electrogenic pump continue to th resting potential
Not a lot
What ion channels open in heart muscle to cause a plateau in charge
Calcium
