Muscular System

Which of the following correctly describes skeletal muscle?

• It is known as voluntary muscle.
• It consists of short, branching fibers that fit together at intercalated discs.
• It is found in the digestive tract, blood vessels, and airways.
• It is called nonstriated because it does not appear striped when examined under a microscope.

What are fascicles?

• Muscle cells
• Groups of muscle fibers
• Types of tendons
• Neurons that innervate muscles

What is the name of the connective tissue that surrounds the muscle as a whole?

• Endomysium
• Epimysium
• Perimysium
• Periosteum

What are myofibrils?

• Long protein bundles that fill the sarcoplasm and store glycogen
• The membrane surrounding each muscle fiber
• Tubules that allow electrical impulses to travel into the muscle cell
• Another name for muscle cells

What is the chief function of T tubules?

• They store glycogen and oxygen
• They store the calcium ions necessary for muscle contraction.
• They contain myofilaments necessary for muscle contraction.
• They allow electrical impulses to travel deep into the cell.

Muscle contraction requires both calcium and __________

• Potassium

• Sodium

• ATP

• Magnesium

Which factor influences the strength with which a muscle fiber contracts?

• The amount of acetylcholine released into the synaptic cleft
• The amount of calcium released
• The length of the muscle fiber before the contraction begins
• The size of the muscle fiber

This state occurs if impulses arrive so fast the muscle cannot relax at all and one prolonged contraction occurs.

• Twitch
• Treppe
• Incomplete tetanus
• Complete tetanus

Also known as the "staircase phenomanon" this is when each successive twitch contracts more forcefully than the previous one.

• Twitch
• Treppe
• Incomplete tetanus
• Complete tetanus

This is defined as the minimum voltage required to produce a muscle contraction:

• Twitch
• Treppe
• Threshold
• Tetanus