Muscular System Structure, Characteristics, and Function

Vocabulary flashcards reviewing muscular system functions, skeletal muscle characteristics, connective tissue wrappings, hierarchical organization, and sarcomere components and contraction mechanisms.

Movement

A main function of the muscular system that moves the body and its parts.

Maintaining posture

A main function of the muscular system that helps you sit and stand upright.

Stabilizing joints

A main function of the muscular system that keeps joints steady during movement.

Heat production

A main function of the muscular system where muscle contractions produce heat to help maintain body temperature.

Excitability

A property of skeletal muscle tissue that allows it to respond to a stimulus.

Contractility

A property of skeletal muscle tissue that allows it to shorten or generate tension.

Extensibility

A property of skeletal muscle tissue that allows it to be stretched.

Elasticity

A property of skeletal muscle tissue that allows it to return to its original shape after being stretched or contracted.

Skeletal muscle tissue

Muscle tissue that is usually under voluntary control, has a striated (striped) appearance, consists of long multinucleated fibers, and is attached to bones by tendons in many locations.

Endomysium

The connective tissue layer that surrounds one individual muscle fiber (cell).

Perimysium

The connective tissue layer that surrounds a bundle of muscle fibers called a fascicle.

Epimysium

The connective tissue layer that surrounds the entire muscle.

Fascicle

A bundle of muscle fibers surrounded and wrapped by perimysium.

Muscle fiber

An individual muscle cell that is long, contains multiple nuclei, and is wrapped by endomysium.

Myofibril

A structural component contained within muscle fibers that consists of repeating sarcomeres.

Sarcomere

The basic contractile unit of skeletal muscle containing actin and myosin filaments, extending from one Z disc to the next.

Z discs (Z lines)

Structures that mark the boundaries of a sarcomere and move closer together when a muscle contracts.

Actin

Thin filaments that slide past thick filaments during muscle contraction without getting shorter themselves.

Myosin

Thick filaments that thin actin filaments slide past during muscle contraction without getting shorter themselves.

A band

The sarcomere region spanning the length of the thick filaments; it stays the same length during contraction.

I band

The sarcomere region containing thin filaments without thick filament overlap; it gets smaller during muscle contraction.

H zone

The central sarcomere region containing thick filaments without thin filament overlap; it gets smaller and may disappear during muscle contraction.

M line

The center of the sarcomere that helps organize thick filaments.

Sarcomere contraction

The process in which thin actin filaments slide past thick myosin filaments, shortening the sarcomere and moving Z discs closer together while the A band stays the same length.