Muscular System Test A

Myoglobin ________.

• breaks down glycogen

• is a protein involved in the direct phosphorylation of ADP

• stores oxygen in muscle cells

• produces the end plate potential

After nervous stimulation stops, what prevents ACh in the synaptic cleft from continuing to stimulate contraction?

• calcium ions returning to the terminal cisternae

• the tropomyosin blocking the myosin once full contraction is achieved

• acetylcholinesterase breaks apart the ACh

• the action potential stops going down the overloaded T tubules

What does excess postexercise oxygen consumption represent?

• amount of oxygen needed for aerobic activity to accomplish the same amount of work

• the difference between the amount of oxygen needed for totally aerobic muscle activity and the amount actually used

• the amount of oxygen equal to the oxygen already used

• the amount of oxygen taken into the body immediately after the exertion

What is the functional unit of a skeletal muscle called?

• a sarcomere

• the sarcoplasmic reticulum

• a myofibril

• a myofilament

What is the role of tropomyosin in skeletal muscles?

• Tropomyosin is the chemical that activates the myosin heads.

• Tropomyosin serves as a contraction inhibitor by blocking the myosin binding sites on the actin molecules.

• Tropomyosin serves as a contraction inhibitor by blocking the actin binding sites on the myosin molecules.

• Tropomyosin is the receptor for the motor neuron neurotransmitter.

Which muscle cells have the greatest ability to regenerate?

• skeletal

• cardiac

• smooth

• no muscle can regenerate

Most skeletal muscles contain ________.

• muscle fibers of the same type

• a mixture of fiber types

• a predominance of slow oxidative fibers

• a predominance of fast oxidative fibers

The strongest muscle contractions are normally achieved by ________.

• increasing stimulus above the threshold

• increasing stimulus above the treppe stimulus

• increasing the stimulation up to the maximal stimulus

• recruiting small and medium muscle fibers

What structure in skeletal muscle cells functions in calcium storage?

• sarcoplasmic reticulum

• mitochondria

• intermediate filament network

• myofibrillar network

Immediately following the arrival of the stimulus at a skeletal muscle cell there is a short period called the ________ period during which the neurotransmitter is released by exocytosis, diffuses across the synaptic cleft, and binds to its receptors.

• contraction

• relaxation

• latent

• refractory