Muscle Contraction Is Triggered

Multiple Choice

Muscle contraction is triggered

A) when high levels of oxygen and sugar are released by the sarcolemma.
B) when a surplus of ATP is released by a nerve motor unit.
C) by release of a neurotransmitter at a synapse that directly causes actin and myosin to slide.
D) by the nerve releasing a neurotransmitter,which triggers a flow of calcium that attaches to actin filaments and exposes the myosin binding sites.
E) by the nerve releasing a neurotransmitter,which triggers a flow of calcium that releases ATP and begins the actin filaments sliding across the myosin binding sites.