Lecture 5 - Biological Basis of Membrane Potential Flashcards
Define and explain the biological basis for resting membrane potential
a. Resting membrane potential is the charge difference across the membrane when the membrane is at rest.
b. The more permeable the membrane is to K+, the more negative the RMP will be.
define depolarisation
Shifts in membrane potential towards 0mV
define repolarisation
shifts in membrane potential towards RMP
define hyperpolarisation
shifts in membrane potential more negative than RMP
what is the Nernst equation used for?
Predicts the equilibrium potential of any ion
what is equilibrium potential?
a. There are two sources of potential energy driving the movement of a specific ion across the cellular membrane
i. Chemical concentration gradient
ii. Electrical charge (gradient)
b. When the two sources of driving force are balanced, the net movement of that ion will be zero. The ion is in equilibrium.
what is driving force (DF)?
a. driving force is a key determinant of ion flux. Ions with higher DF will have more potential energy to move across the membrane
b. DF = Vm -Eion
why is driving force significant?
The DF of any ion gets larger the further the Vm is from Eion. This means that for any two ions, greater energy to move is available to the ion that is furthest away from the Eion.
What is the Goldman-Hodgkin-Katz equation used for?
Used to predict membrane potential given the distribution of ions across the cell membrane and the permeability of the membrane to that ion.
Which of the following can pass through the cell membrane via simple diffusion?
Proteins
Steroids
Na+
Glucose
Steroid
Describe active transport
The direct expenditure of energy (via hydrolysis of ATP) to pump Ca2+ (or any ion) in/out of the cell against its concentration gradient
