Membrane Potential Flashcards
muscle (cardiac skeletal)
-80 to -90 mv
smooth muscle
-60 mv
neurons
-60 to -70 mv
astroglia
-80 to -90 mv
erythrocytes
-9 mv
types of gated channels
- voltage-gated
- ligand-gated
- signal-gated
- mechanically-gated
electrochemical forces
- diffusion forces
- electrostatic forces
equilibrium potentil (Eion)
- membrane potential when electrical and chemical forces are equal
- no further movement occurs
equlibrium potential for Na+
+66 mv
equalibrium potential for K+
-91 mv
Nernst equation
Potassium (K+)
In: 150 mM
Out: 5 mM
E: -91 mv
Sodium (Na+)
In: 15 mM
Out: 150 mM
E: 61.5 mv
Calcium (Ca2+)
In: 0.0002
Out: 2
E: +123 mv
Chloride (Cl-)
In: 10 mM
Out: 120 mM
E: -66.4 mv
effect of increased extracellular K+ concentration
more positive RMP = easier to depolarize
effect of decreased extracellular K+
more negative RMP = more difficult to depolarize cell (cell is hyperpolarized and further from threshold)
insulin (effect on K+)
[Na-K-ATPase]
enhanced cell uptake
beta-catecholamines (effect on K+)
[Na-K-ATPase via + cAMP]
enhanced cell uptake
alpha-catecholamines (effect on K+)
[opposite of beta]
impaired cell uptake
acidosis (effect on K+)
[Donnan effect; inhibition of Na-K-ATPase]
impaired cell uptake
alkalosis (effect on K+)
enhanced cell uptake
[“k is lo”]
external potassium balance (effect on K+)
loose correlation
[ratio vs. total body K+ until severe states]
cell damage (effect on K+)
impaired cell uptake
[release of intracellular contents]
