Properties of Excitable Membranes

Flashcards about Excitable Membranes and Action Potential

Membrane Potential

The potential difference in ion concentrations in and out of the cell separated by a semipermeable membrane.

Resting Potential

Potential observed in a resting cell, used to initiate cell functions.

Action Potential

Potential changes that occur as a result of the movement of ions in and out of the cell when cells are active.

Sodium (Na+)

More outside the cell and tend to enter the cell

Potassium (K+)

More in the cell and tend to leave the cell

Chlorine (Cl-)

More outside the cell and tend to enter the cell

All-or-none Law

States that if an action potential starts, it spreads to the entire membrane or does not start at all.

Depolarization

Outer part of the cell membrane becomes negative and the inner part becomes positively charged due to the Na, K transition.

Repolarization

Restoration of the neuron when impulse conduction is completed.

Hyperpolarization

Repolarization decreases to a little more negative values.

Absolute Refractory Period

Voltage gated Na+ channels are inactive; no AP can be generated

Relative Refractory Period

Voltage gated K+ channels are still open, stronger stimulus is needed, smaller AP is generated.

Oxyhemoglobin

Form of hemoglobin that is fully bound with oxygen in the blood

Nerve Cells

-70 & -80 mV

Skeletal muscle

-90 mV