Anatomy - Muscular System

When a muscle fiber contracts, it _______.

• elongates

• shortens

• thins out

• grows hair

Skeletal muscles are attached to the _________.

• stomach

• lungs

• bones or skin

• involuntary muscles

Skeletal muscles always work in _____.

• antagonistic pairs

• groups of 3

• the brain

• joints

What is the smallest contractile unit of a muscle?

• fascicle

• muscle fiber

• sarcomere

• myofibrils

The ions that are responsible for binding to the troponin-tropomyosin complex and 'unlocking' the active sites on actin is _____.

• Sodium

• Calcium

• Potassium

• Magnesium

What is the name of the protein that makes up the thick filaments?

• actin

• myosin

• myoglobin

• titin

What is the name of the main protein that makes up the thin filaments in the muscle cell?

• Actin

• Myosin

• Myoglobin

• Titin

What is the structure that stores the calcium ions in the muscle cell?

• Sarcoplasm

• Sarcolemma

• Sarcoplasmic Reticulum (Cisternae)

• Myoglobin

The neurotransmitter that initiates a muscle contraction by transferring the nerve impulse to the muscle fiber is called...

• Acetylcholine

• Myosin

• Actin

• Calcium

When a muscle fiber contracts, the I bands become smaller.

• True

• False