Chapter 7 Terms - Muscular System

Moves the body by pulling on bones of skeleton. A bundle of skeletal muscle fibers wrapped in connective tissue layers.

Found only in the heart. Propels blood.

Moves fluid and solids along digestive tract. Regulates diameter of small arteries.

Cell membrane

Cytoplasm

Endoplasmic reticulum (ER)

A network of narrow tubules. Form passageways through the muscle fiber.

Inside each muscle fiber, branches of T tubules encircle cylinder-shaped structures. Bundles of myofilaments.

The myofilaments that make up myofibrils are organized into repeating functional units. The smallest functional unit of the muscle fiber.

Darker band; contains thick and thin filaments.

Lighter band; contains only thin filaments.

Boundary between adjacent sarcomeres.

Lighter band; contains only thick filaments.

Connects central part of each thick filament.

Composed primarily of myosin.

Composed mostly of actin.

Makes up most of the thin filament as a twisted double strand. Contains binding sites for myosin.

Binds to tropomyosin and actin keeping complex in place. Also has binding site for calcium.

Covers myosin binding sites on actin when muscle relaxed.

Muscle cell

A bundle of muscle fibers

Delicate connective tissue surrounding individual muscle fibers

Fibrous layer dividing skeletal muscle into bundles of fibers called muscle fascicles

Dense layer of collagen fibers surrounding entire muscle