Chapter 6

What term refers to a smooth, sustained contraction?

complete tetanus

Contractions in which muscles shorten and produce movement are known as ________.

isotonic contractions

Amelie, a 29-year-old woman, complained to her doctor of being constantly fatigued and having difficulty swallowing. Her speech is slurred and her eyelids are droopy. Amelie most likely has __________.

myasthenia gravis

What term describes the rotation of a bone around its longitudinal axis?

rotation

What organelle wraps and surrounds the myofibril and stores calcium?

sarcoplasmic reticulum

What must rush into a muscle cell to promote its depolarization?

sodium ions

A sarcomere is ________.

the contractile unit between two Z discs

What is released by axon terminals into the synaptic cleft to stimulate a muscle to contract?

acetylcholine

What is covered by the endomysium?

an individual muscle cell

What is the molecular basis of Duchenne's muscular dystrophy?

Muscle fibers lack a protein that helps to maintain the sarcolemma.

According to the sliding filament theory, how does muscle contraction occur?

Myosin heads form cross bridges and pull thin filaments, causing them to slide.

What is acetylcholine?

a neurotransmitter that stimulates skeletal muscle to contract

A smooth, sustained contraction, with no evidence of relaxation, is called ________.

fused, or complete, tetanus