If oxygen is not available to a muscle cell, pyruvic acid is changed to ____ and builds up in the muscle cell.
a. fatty acid
b. phosphocreatine
c. lactic acid
d. glucose
Question 2
As the nerve impulse of an axon reaches the neuromuscular junction, it triggers the release of a neurotransmitter called ____.
a. acetylcholine
b. dopamine
c. epinephrine
d. norepinephrine