Action Potential Flashcards
the rising phase is also known as ____
depolarization
RMP is closest to the Nernst potential for ____ due to…
potassium
large number of potassium channels
RMP is re-established/maintained by ____
Na/K ATPase pump
the falling phase is also known as ____
repolarization
what happens when the RMP reaches -55mV?
voltage-gated Na channels open, Na rushes into cell = depolarization
what happens the membrane potential approaches +40mV?
voltage gated K channels open, K leaves cell = repolarization
if intracellular Cl- is 5mM, and extracellular Cl- is 125mM, what is the equilibrium potential for Cl-?
-85mV
= -61 log (5/125)
if intracellular K+ is 140mM, and extracellular K+ is 5mM, what is the equilibrium potential for K+?
-88mV
= -61 log (140/5)
what causes hyperpolarization?
K+ channels are slow to close, membrane becomes more negative
net driving force is also known as ____
concentration gradient
if extracellular potassium (Ko) becomes to +/ve, what happens to the RMP?
becomes less negative
if the cell were only permeable to K+, reducing the extracellular K+ from 5 to 2.5mM, it would result in ____
hyperpolarization
the RMP of a myelinated nerve fiber is primarily dependent on the concentration gradient of ____
K+
faster conduction velocity would occur in axons with what characteristics?
myelinated
large diameter
what is primarily responsible for the rising phase?
movement of Na+ into the cell
