Graded potentials are local changes in the membrane potential of a cell.  

Graded Potentials

Action potentials are changes in membrane potential that cause cells to become depolarized.  A single action potential only involves a small portion of the total cell membrane.  However, this signal can be propagated through the entire membrane as they do not diminish in strength over distance.  This makes action potentials reliable for long-distance signals.  

Action Potentials

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Nerve and muscle tissue are called "excitable" because they produce electrical signals when excited beyond their resting potential.  These electrical signals are produced by ion movement across the plasma membrane to make the ICF more positive or negative.  

Neural Communication

Sherwood, L. (2010). Human Physiology: From Cells to Systems (7th ed.). Pacific Grove (Calif.): Brooks/Cole.

Human Physiology: From Cells to Systems (7th ed.)

- polarization
- depolarization
- repolarization
- hyperpolarization 

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