Define motor unit, twitch vs. tetanic contraction, isotonic vs. isometric contractions. Describe the two types of isotonic contractions.

Isometric Contraction(same length)

Is when muscle stays the same length, no movement.

Motor Unit

Muscle fibers are stimulated by a nerve fiber called a motor neuron

Isotonic Contraction(same tension)

The same tension, thus muscle length is changing. There are two possibilities muscle lengths and muscle shortens.

tetanic contraction

is a contraction due to many impulses, in rapid succession. Causes a smooth, steady contraction. Ex lock jaw

Twitch

is a contraction due to one nerve impulse. That causes a quick, jerky contraction.