Chemical gradient
Substances move from areas of high concentration to low concentration
electrical gradient
Like charges repel
Opposite charges attract
Electrochemical gradient
The electrical and chemical forces acting on substances that determine ion movement
What is the main function of the Na+/K+ ATPase
Establishes and maintains ECF and ICF concentrations
How many K+ channels are in nerves
A relatively large amount (100x more than Na+)
What ion is a resting nerve cell most permeable to
K+
Why does K+ passively leave cells
Has a large concentration gradient driving it out
Why does K+ passively enter cells
The inside of a cell is negative, attracting positive K+
What is an equilibrium potential
The transmembrane voltage at which ion flow into and out of a cell is exactly matched
What does the membrane potential depend on
- concentration gradients of different ions
- relative permeability to ion flow into
What ion is most important in determining RMP
K+
What equation calculates RMP
Goldman-Hodgkin-Katz equation
Goldman-Hodgkin-Katz
Calculates RMP
What equation calculates equilibrium potential for an ion
Nernst equation
Unit for equilibrium potential
mV
K+ Ek
-94mV
Na+ Ek
+65mV
What happens if the cell membrane becomes much more permeable to Na+
Na+ enters the cell and makes inside of the cell positive
