MYSCLE FIBERS PT1

Skeletal Fiber

The skeletal muscle cell, which is a long, fiber-like cell responsible for muscle contraction.

Endomysium

The thin layer of connective tissue that surrounds each individual skeletal muscle fiber.

Perimysium

The connective tissue sheath that groups together several muscle fibers to form a fascicle.

Fascicle

A bundle of skeletal muscle fibers grouped together within the perimysium.

Epimysium

The outer connective tissue sheath surrounding multiple fascicles in a skeletal muscle.

Myocyte

The technical term for muscle cells, also known as muscle fibers.

Sarcoplasm

The semi-fluid material within a myocyte, analogous to cytoplasm in other cells.

Sarcoplasmic Reticulum

A specialized form of smooth endoplasmic reticulum in muscle cells, involved in calcium storage and release.

Myofibrils

Cylindrical organelles found within myocytes, composed of contractile proteins that facilitate muscle contraction.

T Tubules (Transverse Tubules)

Inward extensions of the sarcolemma that allow extracellular fluid to penetrate into the muscle fiber.

Triad

The structure formed by a T tubule flanked by two terminal cisternae of the sarcoplasmic reticulum.

Myofilaments

The structural proteins within myofibrils responsible for muscle contraction, including thick and thin filaments.

Thick Filaments

Myosin filaments that have globular heads involved in binding with actin during muscle contraction.

Thin Filaments

Actin filaments that contain active sites for myosin binding, along with regulatory proteins tropomyosin and troponin.

Sarcomere

The functional unit of contraction in skeletal muscle, defined as the segment between two Z discs.

I Band

The light-colored region of the sarcomere, containing only thin filaments.

A Band

The darker region of the sarcomere, containing both thick and thin filaments.

H Zone

The section within the A band that contains only thick filaments.

M Line

The structural center of the sarcomere where thick filament tails are connected.

Z Disc

The zig-zag boundary that defines the ends of a sarcomere and anchors thin filaments.

Titin

An elastic filament that stabilizes myofibril structure and resists excessive stretching.