Lec 2 Flashcards
Components of the lipid bi-layer
Phospholipids
Hydrophilic heads
Hydrophobic tails
Resting membrane potential inside membrane
-70mV
Strong concentration of K+ inside cell and low concentration of Na+ and Cl-
Large anions, such as protein also affect membrane potential
Leak channels
Allows ions to diffuse across the membrane
Equilibrium potential
Membrane potential at which there is no net movement into or out of the cell
This is dependent on the intra and extra-cellular concentrations of the ions
Driving Force
Difference between membrane equilibrium potentials (difference between membrane potentials of K+, Na+ and Cl-)
K+, Na+, and Cl- membrane nature
K+ will diffuse out
Na+ will diffuse in
Cl- will stay in place
Why is K+ crossing more than Na+
The membrane is more permeable to K+ than Na+ (easier to access leak channels)
What would happen if the permeability of Na+ increased
Cell would have a more positive membrane potential
How can you change the membrane potential
Changing the permeability of the membrane to certain ions
Why can’t charge particles enter through the phospholipid bilayer
Particles are surrounded by water
Why do ions tend to move
Electrical and concentration gradients
Donnan Equilibrium
The phenomenon that explains the unequal distribution between intercellular and extracellular cells
E=RT/zF ln (Ion outside cell/Ion inside cell)
Equilibrium potential equation
R=Universal gas constant
T=Temp
z=Valence of ion
F=Faraday constant
Goldman-Hodgkin-Katz (GHK) equation
Use this equation to determine membrane potential at any time if you are changing permeability to certain ions
Voltage thermometer
where you could change the membrane potential by changing the permeability to any of the ions
