The Resting Potential Flashcards
Benefits of nervous system transmission and mechanisms?
Reliable
Quick
Uses resting and action potentials
Definition of flux?
The number of ions that cross a unit area per unit time
Zero reference point of resting potential location?
OUTSIDE THE CELL
Resting potential measured with?
Voltmeter
States of K+ and Na+ ungated and voltage-gated channels?
Ungated channels always open
Voltage-gated are open/closed depending on their conformation as a result of changing membrane potential
What is the electrochemical equilibrium of an ion?
The point reached when the ion’s concentration gradient is balanced by the electrical gradient across the membrane
What is the equilibrium potential of an ion?
The electrical potential that prevents diffusion of the ion down its concentration gradient
What is the Nernst equation used for?
To calculate the size of an equilibrium potential of an ion
Basically what the membrane potential will be if the membrane is permeable to a certain ion
Most important ions for resting potential?
Na+ and K+
Which ion equilibrium potential is the resting membrane potential closest to and why?
Normal resting membrane potential is -70mV
This is closest to K+ equilibrium potential
This is because the membrane is more permeable to K+ than Na+
Process of resting membrane potential generation?
K+ diffuses out of the cell down its concentration gradient through permanently open channels, inside of the cell becomes negative
Slight permeability of membrane to Na+ means some Na+ moves into the cell
Overall the resting membrane potential becomes slightly more positive than equilibrium potential of K+
Types of changes in membrane potential?
Depolarisation
Overshoot (depolarisation past 0 positively)
Repolarisation
Hyperpolarisation (more negative than resting potential)
What is decremental spread?
The magnitude of membrane potential change DECREASES with TIME and with distance from stimulus site
What causes changes in membrane potential and where do these occur?
Stimulation causes change
Occurs at synapses or sensory receptors
