Generation and regulation of membrane potentials Flashcards
What is the membrane potential?
the potential difference between the inside and outside of the cell
Carriers/ exchangers
concentration gradient
primary active transport
uses ATP as energy source
secondary active transport
uses ionic gradient as energy source
how do you measure membrane potential?
using a microelectrode which penetrates the cell membrane
What are the resting membrane potentials for the following?
- Neurones
- Cardiac Muscle
- Skeletal muscle
- 65mv
- -85mv
- 90mv (most negative)
What is depolarization?
a decrease in the size of the membrane potential from its normal value
cell interior becomes less negative
less negative to more positive
What is hyperpolarization?
An increase in the size of the membrane potential from its normal value
cell interior becomes more negative
What does increasing the membrane permeability to a particular ion do?
this moves the membrane potential towards the EQUILLIBRIUM POTENTIAL for that ion
How can we affect the membrane potential?
change the membrane permeability for that ion by opening ion channels
What do excitatory transmitters do?
open ligand gated channels that cause membrane depolarisation
what is the resulting change in membrane potential called?
excitatory post synaptic potential
what do inhibitory transmitters do?
open ligand gated channels that cause hyperpolarisation
What do you need to generate an action potential?
depolarisation of the membrane potential rapidly
a way to repolarise the membrane potential
ability to generate another action potential soon after
action potential has to have the ability to travel along the cell from one end to the other without loss of altitude
When is equilibrium reached?
when the two forces completely counteract and the movement is 0
