Muscular System Overview

These flashcards cover key concepts, terminology, and functional characteristics relating to the muscular system.

Skeletal Muscle Functions

Includes body movement, maintenance of posture, respiration, heat production, communication, constriction of organs and vessels, and heartbeat.

Contractility

The ability of muscle to shorten forcibly.

Excitability

The capacity of muscle to receive and respond to stimuli.

Extensibility

The ability of muscle to be stretched or extended.

Elasticity

The ability of muscle to recoil and return to its original resting length.

Types of Muscle Tissue

The three types are skeletal, smooth, and cardiac, differing in structure, location, function, and means of activation.

Fascia

Connective tissue sheets that separate and compartmentalize muscles.

Myofibrils

Densely packed, rod-like contractile elements making up most of the muscle volume.

Sarcomere

The smallest contractile unit of muscle, bound by Z disks holding actin myofilaments.

Actin Myofilaments

Thin myofilaments consisting of two helical polymer strands of F actin, along with tropomyosin and troponin.

Myosin Myofilaments

Thick myofilaments composed of myosin molecules with a head, hinge region, and rod.

Z Disk

A coin-shaped sheet of proteins that anchors thin filaments and connects myofibrils.

A Band

The dark band of a sarcomere where thick myofilaments are present.

I Band

The light band of a sarcomere representing only thin myofilaments.

M Line

The line at the center of the A band where thick myofilaments are anchored.

H Zone

The area in a sarcomere that appears lighter where thin filaments do not overlap thick filaments.

Structural Hierarchy of Skeletal Muscle

Organized structure starting from muscle to fascicle, muscle fiber, myofibril, and myofilaments.