Week 11 Review
What was covered:
- Voltage gated ion channel
- Gating currents
- Model for Sodium and Potassium channel
- State model
Voltage gated channel
in
+
out
-Probabilistic gate. Probability that gate is open depends on voltage across
membrane.
Gating curr ents
The gate has charge on it. (Remember: charge on gate is why probably of being open
changes with voltage.)
Therefore, the movement of the gate opening and closing causes a current. That is called
the gating current.
What about Sodium and Potassium ch annels?
Sodium and Potassium channels can’t just be modeled as one gate because
- Sodium channel has inactivation as well as activation
- Potassium channel has S- shape onset not exponential
Use 4 gates to model single channel!
Sodium: Potassium:
in in
+
+
+
-
+
+
+
+
out out
