Neuronal Excitability Flashcards
What does the Na+ gradient facilitate?
solute uptake or extrustion
What does the K+ gradient facilitate?
solute extrusion
classify the following as primary or secondary active transporters:
- Na-K-ATPase
- Na-Ca-antiporter
- K-Cl-cotransporter
- pH control antiporter
primary: Na-K-ATPase
secondary: antiporters and cotransporters
TRUE or FALSE: the cell membrane is permeable to both protein anions and potassium ions.
FALSE: impermeable to protein anions
What are the 2 forces that contribute to the electrochemical gradient?
chemical (concentration) force and electromotoric (potential) force
Which equation is used to calculate the equilibrium potential of an ion?
Nernst equation
Why is Vm close to Ek?
glial cells have a very high resting conductance (ease with which ions can flow across the membrane)
What is the Nernst equation used for?
determination of equilibrium potential VIA ION GRADIENT
Why does the overshoot of an AP not reach +60 mV?
Na+ channels close and
label conductance for slide 4 in the diagram and describe events of an AP (i.e. recreate the diagram and label)
see slide
When are the leak K+ and Na+ channels open?
always open
What is the threshold potential?
-40 mV
What is the diagram on the right of slide 6 demonstrating?
although current injected increases suprathreshold, the action potential elicited spike the same –> this implies that APs are an all-or-none response
Where on an axon are majority of the V-gated Na+ channels located? What does the location imply about AP generation?
at the axon hillock –> therefore APs are generated closer to the soma than the dendrites
Why was the patch-clamp technique originally developed?
to prove that ion channels exist and a very small current flow can be measured, even through a single activated channel
