Origin of membrane potentials Flashcards
The energy (potential) between opposite charges can be harnessed to do work. True or false?
True.
What is the membrane potential (Em)?
The separation of opposite charges across the membrane. In mV units.
Is the membrane itself charged?
No.
Is the relationship between the number of charges and the membrane potential proportional or inversely proportional?
Proportional.
What is the membrane potential due to?
Differences in the concentration and permeability of key ions.
Does K+ or Na+ have higher relative permeability?
K+ has higher relative permeability.
Why does K+ have higher relative permeability than Na+.
In skeletal muscles, there are more leak channels for K+ than Na+ so there are more K+ ions inside cell.
Where is Na+ predominantly found?
Outside of cell
Where is K+ predominantly found?
Inside the cell
What is the equilibrium potential for K+?
-90mV
What is the equilibrium potential for Na+?
+61mV.
What two forces become balanced to reach equilibrium?
Attraction to area of lower concentration (concentration gradient)
repulsion of same charged ions (electrical gradient)
What is the value of the resting membrane potential?
-70mV.
Are cells negative or positive inside at rest?
Negative.
What causes changes in the membrane potential?
Opening and closing of K+ and Na+ channels at different times.
