Structure of Muscles

What is the name of the thick myofilaments?

• actin

• myosin

• myoglobin

• tropomyosin

What is the name of the thin myofilaments in the muscle cell?

• actin

• myosin

• troponin

• collagen

The contractile unit of a muscle is called the __________.

• Sarcolemma
• Sarcoplasmic reticulum
• Sarcoplasm
• Sarcomere

Number 3 represents which of the following events

• action potential reaches the terminal branches

• sodium rushes into the muscle fiber

• calcium leaving the sarcoplasmic reticulum

• ACh crossing the synapse

Contractions are generated by

• shortening of thick filaments
• shortening of thin filaments
• sliding of thin filaments past thick filaments
• "accordian-like" folding of thick and thin filaments

Once calcium is released, it will

• attach to the myosin heads

• attach to receptors in the T-tubules

• attach to actin receptors

• attach to the troponin to expose actin receptors

The diagram represents the neuromuscular junctions. Z is pointing to which of the following?

• sodium ions used to generate an impulse in the muscle fiber

• calcium ions used to trigger muscle contraction

• acetylcholine used to stimulate the muscle to contract

• potassium ions used to repolarize the neuron

Actin is represented by number...

• 7

• 5

• 4

• 3

Which structure stores calcium in the muscle cell?

• Sarcoplasm

• Sarcolemma

• Sarcoplasmic Reticulum

• Myoglobin

When all of the sodium channels open in the muscle cell membrane, a(n) ________ is created.

• negative charge

• resting potential

• muscle twitch

• impulse