Lecture 6 - transport and electrophysiology Flashcards
Diffusion
Movement of solute molecules from high to low concentration
Move down (with) concentration gradient until equilibrium (not net movement) is reached
Osmosis
The movement of water (solvent) through a semipermeable membrane from a region of low solute concentration to a region of high solute concentration
Transport across membrane is
Molecules pass through phospholipid bilayer without membrane protein (non-polar)
facilitated diffusion
Charged or polar solutes such as ion and glucose cross the phospholipid bilayer with the help of membrane proteins
Carrier proteins
Ion channel
Simple diffusion
Molecules pass through phospholipid bilayer without membrane protein (non-polar)
Electrical gradient
the difference in the net charge between two regions
Electrochemical gradient
combination of electrical and concentration gradients
Resting membrane potential
The electrical charge of a neuron when it is not active (-67 to -70)
Voltage
Electrical gradient established by separation of charges between two locations
Current
Flow of electrical charge between two points
Flow is dependent on
Voltage and resistance
Conductance
Relative ability of an electrical charge to migrate from one point to another
Resistance
Hindrance to charge flow; inability of charge to migrate
Insulator
Substance with high electrical resistance
Conductor
substance with low electrical resistance
OHM law
Current is the product of conductance and potential difference
No electricity of non permeable membrane is present
OHM equation
I = Vg
Equilibrium potential
Electrical potential difference that exactly balances on ion concentration gradient
Large changes in membrane potential are cause by
Small change in ionic concentration
Only ion at the film of the membrane
will be significantly chaning
Ionic driving force
the difference between the real membrane potential and the equilibrium potential
Nerst equation
Predict the equilibrium potential that a single ion would produce if the membrane were permeable to only that ion
Potential is influenced by
concentration gradient of ion
membrane permeability to those ions
Goldman equation
Calculates the resting membrane potential considering the relative permeability of different ions
Ion channels
Transmembrane proteins which allow certain substances to cross membrane and pass into or out of cell
Electrical changes across neuron plasma membrane relay on
ion channels resting membrane potential
Leak channels
Specialized ion channels that are always open, allowing a continuously flow of ions down their concentration gradients between cytosol and ECF
RMP is negative because
More K leaks out than Na leaks in
Cell is polarized when
voltage difference across plasma membrane does not equal 0
