Anatomy Chapter 10 Muscle Tissues

Skeletal muscle tissue

Voluntary, striated tissue attached to bones; responsible for movement and posture.

Epimysium

Connective tissue surrounding entire muscle.

Perimysium

Connective tissue surrounding fascicles (bundles of fibers).

Endomysium

Connective tissue surrounding individual muscle fibers.

Myofibril

Cylindrical structures within muscle fibers composed of myofilaments.

Sarcomere

Functional unit of muscle contraction; region between Z-discs.

Actin

Thin filament protein involved in muscle contraction.

Myosin

Thick filament protein with heads forming cross-bridges to actin.

Sliding filament theory

Muscle contraction occurs as thin filaments slide past thick filaments, shortening sarcomeres.

T-tubules

Invaginations of the sarcolemma that carry impulses deep into the cell.

Sarcoplasmic reticulum

Stores calcium ions necessary for contraction.

Isometric contraction

Muscle tension increases but muscle length stays the same.

Isotonic contraction

Muscle changes length (concentric or eccentric) during contraction.

Slow oxidative fibers (Type I)

High endurance, slow contraction speed; many mitochondria and myoglobin.

Fast glycolytic fibers (Type IIb)

Fast contractions, low endurance; large glycogen stores.