5: Origin of membrane potentials Flashcards
The plasma membranes of all cells are (polarised / depolarised).
polarised
What is membrane potential (Em)?
Separation of opposite charges across the membrane
What is the unit of membrane potential?
millivolts (mV)
Membrane potential is a measure of the difference in charge between the _CF and _CF.
ECF and ICF
What is the name given to a rapid, transient change in membrane potential?
Action potential
What is an action potential?
A rapid, transient change in membrane potential
Which type of cells can produce action potentials?
Excitable cells such as nerves and muscle
Na+ is highly concentrated (inside / outside) cells.
inside
K+ is highly concentrated (inside / outside) cells.
outside
Cl_ is highly concentrated (inside / outside) cells.
outside
The Na+ concentration gradient is (inward / outward).
inward
The K+ concentration gradient is (inward / outward).
outward
What is the equilibrium potential of an ion?
The membrane potential at which the concentration gradient of the ion equals the electrical gradient in the opposite direction
What is the equilibrium potential for K+?
-90mV
What is the equilibrium potential for Na+?
+60mV
What is the permeability of K+ compared to that of Na+?
Around 100x greater
What is the permeability of Na+<strong> </strong>compared to that of K+?
Around 100x less
The greater the ___ of an ion, the greater the tendency of that ion to drive the membrane potential towards its own ___ potential.
permeability , equilibrium potential
What is the typical resting membrane potential for a nerve cell?
-70mV
Why is the resting membrane potential for a nerve cell around -70mV?
Tends towards EK+ (-90mV) because K+ is 100x more permeable than Na+
However, not equal to EK+ because of inward Na+ leak
What equation can be used to calculate the equilibrium potential of an ion?
Nernst equation
What equation can be used to calculate the membrane potential of a cell?
GHK equation
Which integral protein can have an effect on the membrane potential of a cell?
Na+-K+ATPase
(sodium-potassium pump)
The sodium-potassium pump generates a
(depolarising / repolarising / hyperpolarising)
current.
hyperpolarising
Which types of cells will have fluctuating membrane potentials?
Nerve cells
Muscle cells
as they generate action potentials a lot.
Which ion is most important in setting the membrane potential?
K+<strong> </strong>(100x more permeable than sodium)
