BIOL 2401 Muscle Pre-Lab and Structural Organization

Comprehensive vocabulary flashcards reviewing muscle types, directional movements, contraction mechanics, sarcomere banding, and anatomical connective tissue layers from the BIOL 2401 Muscle Pre-Lab.

Skeletal Muscle

Striated, voluntary muscle tissue attached to bones that facilitates body movement and posture.

Cardiac Muscle

Striated, involuntary muscle tissue found exclusively in the heart wall, characterized by branching fibers and intercalated discs.

Smooth Muscle

Non-striated, involuntary muscle tissue found within the walls of hollow organs and blood vessels.

Abduction

Movement of a limb or body part laterally away from the midline of the body.

Adduction

Movement of a limb or body part medially toward the midline of the body.

Flexion

A bending movement that decreases the angle between two articulating bones or body parts.

Extension

A straightening movement that increases the angle between two articulating bones or body parts.

Origin

The fixed or less movable attachment site of a skeletal muscle, typically located proximally.

Insertion

The movable attachment site of a skeletal muscle that is pulled toward the origin during contraction, typically located distally.

Concentric Contraction

An isotonic muscle contraction where the muscle generates tension and actively shortens to overcome resistance.

Eccentric Contraction

An isotonic muscle contraction where the muscle generates tension while lengthening to control or decelerate movement.

Isometric Contraction

A muscle contraction where internal tension increases, but the muscle length and joint angle remain unchanged.

Sarcomere

The basic contractile functional unit of a myofibril, extending from one Z disc to the adjacent Z disc.

Sarcolemma

The specialized plasma membrane that encloses an individual muscle fiber.

Actin

The primary contractile protein found in thin filaments of a sarcomere that contains binding sites for myosin heads.

Myosin

The contractile motor protein that forms thick filaments, featuring globular heads that pull on actin filaments during contraction.

Z Disc

A narrow, dense protein plate that anchors thin actin filaments and marks the boundary between adjacent sarcomeres.

H Zone

The lighter, narrow central region within the A band of a sarcomere consisting exclusively of thick (myosin) filaments.

A Band

The dark band of a sarcomere that spans the entire length of the thick (myosin) filaments, including regions where actin overlaps.

I Band

The light band of a sarcomere composed solely of thin (actin) filaments, bisected down the center by a Z disc.

M Line

A fine, dark protein structure in the exact center of the H zone that anchors and stabilizes adjacent thick filaments.

Skeletal Muscle Connective Tissue Layers

The nested fibrous sheaths (epimysium, perimysium, and endomysium) that wrap and organize skeletal muscle components into tendons.

Epimysium

The outer dense layer of connective tissue that encases the entire skeletal muscle organ.

Perimysium

The fibrous connective tissue sheath that gathers muscle fibers into discrete bundles known as fascicles.

Endomysium

The delicate, innermost layer of loose connective tissue that surrounds each individual muscle fiber.

Fascicle

A discrete bundle of skeletal muscle fibers bounded together by the perimysium.

Muscle Fiber

An individual, elongated, multinucleated skeletal muscle cell composed of numerous myofibrils.

Tendon

A tough cord of dense regular connective tissue that anchors a muscle directly to a bone.