05 Neuron electrical signaling Flashcards
1
Q
Hyperkalemic Periodic Paralysis
A
- Some muscle voltage-gated Na+ channels cannot inactivate after depolarization
- results in small, constant inward Na+ current that depolarizes and therefore inactivates the normal Na+ channels, making AP not possible. Muscle not excitable.
2
Q
Myotonia
A
- Muscle does not relax after contraction
- Mutuation in skeletal muscle Cl- channel results in low Cl conductance, so resting membrane potential closer to threshold. Muscle is hyperexcitable with prolonged contraction.
2 similar types:
- Thomsen’s myotonia
- Becker’s myotonia
-“Fainting” goats
3
Q
Nernst equation
A
Resting potential = 61/Z log (C outer/C inner)
4
Q
Puffer Fish toxin, mechanism?
A
Tetrodotoxin (TTX):
blocks Na channels–paralysis, numbness, weakness
death from respiratory paralysis
5
Q
Length constant
A
distance at which potential decreases by 63%
6
Q
Skeletal muscle vs. neuron: resting membrane potential difference and why
A
Skeletal muscle: -95 mV
Neuron: -70 mV
In skeletal, Cl- channels also contribute to RMP. (Cl- equilibrium is -80, and its conductance fraction is 0.45 that of K+)
