Muscular System: Skeletal Muscle Structure and Function

Vocabulary flashcards covering the gross anatomy, microscopic organization, characteristics, and physiological components of skeletal muscle from Chapter 10.

Excitability

The ability to respond to a stimulus by changing the electrical membrane potential of the cell.

Conductivity

The muscle characteristic that involves sending an electrical charge down the length of the cell membrane.

Contractility

The characteristic exhibited when filaments slide past each other, enabling muscles to cause movement.

Extensibility

The ability of muscles to be stretched.

Elasticity

The ability of a muscle to return to its original length after it has either been shortened or lengthened.

Fascicle

A bundle of multiple muscle fibers that together make up a whole skeletal muscle.

Muscle fiber

An individual muscle cell found within a fascicle.

Epimysium

A layer of dense irregular connective tissue that wraps around the entire muscle like saran wrap.

Perimysium

Dense irregular connective tissue that wraps around fascicles and houses blood vessels and nerves.

Endomycium

Delicate areolar connective tissue around each muscle fiber that provides capillary support and binds fibers together.

Tendon

A cord-like structure composed of dense regular connective tissue that connects muscle to bone, skin, or other muscle.

Aponeurosis (upon neurosis)

A thinned, flattened sheet of dense regular connective tissue that attaches muscle to other structures.

Deep fascia

Dense irregular connective tissue superficial to the epimysium that separates individual muscles while binding muscles with similar functions together.

Superficial fascia

Areolar and adipose connective tissue located superficial to the deep fascia that separates muscles from the skin.

Somatic motor neurons

Neurons that innervate skeletal muscle to allow voluntary control over contractions.

Sarcoplasm

The cytoplasm of a muscle fiber containing typical organelles, contractile proteins, and muscle-specific components.

Sarcolemma

The plasma membrane wrapping around the muscle fiber deep to the endomycium, containing voltage-gated ion channels.

Transverse tubules (T tubules)

Tubules that extend deep into the cell to conduct electrical signals that trigger calcium release.

Myofibrils

Bundles of myofilaments found inside a muscle fiber.

Sarcoplasmic reticulum

An internal membrane complex containing calcium release channels that release calcium into the sarcoplasm when triggered by an electrical signal.

Thick filaments

Myofilaments composed of bundles of myosin protein that feature two heads at the end that bind to actin.

Thin filaments

Myofilaments made of twisted strands of actin containing binding sites for myosin heads.

Tropomyosin

A regulatory protein identified as a thread-like structure located on actin.

Troponin

A regulatory protein identified as dot-like structures located on actin.

Sarcomere

The repeating structural unit of skeletal muscle composed of overlapping thick and thin filaments.

Z disc

A perpendicular structure found at either end of a sarcomere that marks its boundaries.

I band

An area of the sarcomere that contains only thin filaments (actin) and crosses over the Z disc.

A band

An area of the sarcomere that contains thick filaments (myosin).

Myoglobin

A molecule found within muscle cells that stores oxygen to be used for ATP production.

Glycogen

A substance stored in muscle cells that is utilized when fuel is quickly needed.