Skeletal Muscle Structure Quiz

Myofibrils

• Long, rod-like structures found within muscle fibers.
• Composed of repeating units called sarcomeres, which contain actin and myosin filaments.
• Responsible for muscle contraction through sliding filament mechanism.

Sarcoplasmic Reticulum

• Specialized endoplasmic reticulum in muscle cells.
• Stores calcium ions essential for muscle contraction.
• Releases calcium when stimulated to trigger contraction and reabsorbs it to relax the muscle.

Sarcolemma

• The plasma membrane surrounding each muscle fiber.
• Functions to maintain the internal environment of the muscle fiber and conduct electrical impulses.
• Plays a key role in transmitting action potentials throughout the muscle fiber.

Epimysium

• A connective tissue layer that encases the entire muscle organ.
• Provides structural integrity and support to the muscle.
• Contains blood vessels and nerves that supply the muscle.

Perimysium

• Connective tissue that surrounds groups of muscle fibers, forming fascicles.
• Provides a pathway for nerves and blood vessels to travel to individual muscle fibers.
• Contributes to the overall strength and elasticity of the muscle.

Endomysium

• Delicate connective tissue that surrounds each individual muscle fiber.
• Provides support and nutrient exchange between muscle fibers and capillaries.
• Contains satellite cells important for muscle repair and regeneration.

Fascicle

• A bundle of muscle fibers grouped together within the muscle.
• Surrounded by perimysium, allowing for coordinated contraction.
• The arrangement of fascicles contributes to the muscle's strength and direction of force.

Muscle Fiber

• The basic functional unit of skeletal muscle.
• Multi-nucleated cells that contain myofibrils, sarcoplasmic reticulum, and sarcolemma.
• Able to contract in response to neural stimuli and can vary in type (slow-twitch vs fast-twitch fibers).