1.4 Resting Membrane Potential Flashcards
What is the resting potential of a membrane and how is it determined
-70 mV. The voltages across a neuronal membrane at rest. It is determined by the concentration gradients of ions across the membrane and how permeable the membrane is to the ions.
What ion the the neuronal membrane more permeable towards, K+ or Na+.
The membrane is more permeable to K+ than to Na+ so the resting potential is close to the equilibrium potential of K+
How can potential difference by measured
The PD can be measured by placing an electrode inside the cell and measuring compared to the bath electrode outside of the cell
What triggers can activated gated ion channels
Voltage and Ligands
What determines how ions move across the membrane to reach their equilibrium
The concentration gradient, ionic gradient and chemical gradient form the electrochemical gradient which pulls on the ions so that equilibrium can be reached
What would the equilibrium potential be if K+ was acting alone
-90mV
What would the equilibrium potential be if Na+ was acting alone
+60mV
How many times more permeable is the resting membrane to K+ than Na+
The resting membrane is 25 to 30 times more permeable to K+ than to Na+
What happens when Na+ gradually leaks into the cell over time
This makes the interior less negative which reduces the electrochemical gradient. This causes more K+ to leave the cell to reach a new equilibrium.
What is in place to compensate for Na+ gradually leaking into the cell
The Na+/K+ -ATPase pump is another membrane spanning protein complex that requires energy (ATP is hydrolysed by the ATPase). It pumps out 3 Na+ for every 2 K+ brought in, this acts to keep the resting potential at -70mV.
