Resting potential Flashcards
When does resting potential occur?
when a neurone is not transmitting an impulse
Why does resting potential occur?
the PD across its membrane (difference in charge) is known as resting potential
What are the condition for resting potential and what is the figure?
the outside of the membrane is more postively charged than the inside of the axon
the membrane is said to be polarised as there is a PD across
it is uaully about -70mV
What causes the resting potential?
result opf the movemenbt of sodium and potassium ions across the axon membrane
How do ions move across the membrane?
the phospholipid bilayer prevents these ions from diffusing across the membrane and they have to be transported via channel proteins
some of these channels are gated - they have to be opened to allow specific ions to pass through them
others remain open all of the time allowing sodium and potassium to simply diffuse
Which direction are sodium and potassium ions transported?
Na+ ions are actively transported out the axon, wheras K+ is actively transported into the axon, by a specific intrinsic protein known as the sodium-potassium pump
their mopvement is now equal, for every three sodium ions that are pumped out, two potassium ions are pumped in
What is the result of this transport?
there are more sodium ions outside the membrane than inside the axon cytplasm, whereas there are more potassium ions inside the cytoplasnt than outside the axon
therefore sodium ions diffuse back into the axon down its electrochemical gradient (concentration gradient of ions), whereas potassium ions diffuse out the axon
What is the difference between the channels for the two ions? Why does this occur?
most of the gated sodium ion channels are closed, wheras potassium ion channels are open, thus allowing potassium ions to diffuse out the axon
therefore there are more positively charged ions outside the axon than inside the cell
this creastes a negative resting potential
