Bioelectricity Flashcards
What is membrane potential critical for
cell function
True or False - ALL cells have membrane potentials
TRUE
How do you measure membrane potential
Impail the cm into the intracellular fluid compartment with glass electrode, measure in respect to 0mV fluid
What determines membrane potential
unequal distribution and selective movement of ions
What does Vm stand for
membrane potential
What transporter maintains normal cell membrane potential / environment
Sodium potassium ATPase
What is the contribution of the sodium potassium ATPase to the resting membrane potential
contributes 20% directly
How does sodium potassium ATPase contribute to the resting membrane potential.
Na+/K+ ATPase carries one positive charge out of the cell
What is the effect of the Na+/K+ ATPase carrying one positive charge out of the cell
leaves a negative charge inside the cell, this maintains the driving force
Describe the concentration gradient for potassium movement in relation to the cell
concentration gradient for potassium to move out of the cell
What is the effect of potassium moving out of the cell
inside of the cell becomes more negative
What ions cannot cross the cell membrane
anions
Why is it important that anions cannot cross the cell membrane
allows cell to generate negative membrane potential
What is the current when there is no NET movement of potassium
0 current
What is the potential called when there is no NET movement
Nernst potential
What is the effect of ion movement on membrane potential
move the membrane potential towards their Nernst potential
What does it mean if a cells membrane potential is -70mV
potassium channels are working and functional
Why is the cells membrane potential slightly more positive than the Nernst potential for potassium
Sodium channels can be slightly leaky
Describe the concentration gradient for sodium movement
sodium moves into the cell down its conc gradient
What is the effect of sodium influx on the cell potential
makes the membrane potential more positive
What is the Nernst potential for sodium
+61.5
What is the effect of sodium channels opening on the membrane potential
shift the membrane potential towards the Nernst potential for sodium
What does the Goldman equation calculate
Membrane potential
What does the Goldman equation give us information about
membrane permeability
What would the cells membrane potential be if only sodium channels were open
+60mV
Why does the influx of sodium generate an action potential
when voltage gated sodium channels open the influx of sodium drives the membrane potential towards its Nernst potential - positive
Describe the repolarisation phase of the action potential with reference to potassium and their Nernst potential
at the peak of the action potential, potassium channels open and drive the membrane potential towards its Nernst potential - negative
What is different about Na+ amino acid co transport in the epithelial cell with reference to the membrane potential
Repolarisation occurs when potassium channels open however this is more gradual and the co transporter remains open
