Muscle Tissue

Skeletal Muscle

Striated, voluntary muscle that attaches to bone

Smooth Muscle

Non-striated, involuntary muscle found in soft tissues and vessels

Cardiac Muscle

Striated, involuntary muscle exclusively found in the heart

Endomysium

Loose connective tissue surrounding muscle fibers

Perimysium

Loose connective tissue surrounding muscle fascicles, carries blood vessels

Epimysium

Dense connective tissue surrounding entire muscle

Skeletal Muscle Fiber

A multinucleated syncytium (one muscle cell)

Myofibril

Contractile element of muscle fiber, composed of sarcomeres

Myofilaments

Filamentous proteins responsible for muscle contraction

Sarcolemma

Plasma membrane of a muscle fiber

Sarcoplasmic Reticulum

Specialized endoplasmic reticulum in muscle cells, stores calcium ions

T-tubule

Invagination of the sarcolemma, conducts action potentials deep into the muscle fiber

Triad

Structure formed by a T-tubule and two terminal cisternae of the sarcoplasmic reticulum

Duchenne Muscular Dystrophy

Genetic disorder characterized by progressive muscle degeneration and weakness

Motor Innervation

Nerve signal transmission to muscle fibers

Myasthenia Gravis

Autoimmune disease causing muscle weakness due to antibodies blocking acetylcholine receptors

A-band

Dark region of a sarcomere, contains thick filaments

I-band

Light region of a sarcomere, contains thin filaments

H-zone

Region of a sarcomere containing only thick filaments

Actin

Thin filament protein involved in muscle contraction

Myosin

Thick filament protein involved in muscle contraction

Intercalated Discs

Cell junctions between cardiac muscle cells, allow for communication and coordinated contraction

Myocardial Infarction

Heart attack, caused by blockage of blood flow to the heart muscle

Smooth Muscle Fiber

Single mononucleated cell of smooth muscle

Gap Junctions

Channels between smooth muscle cells, allow for electrical and chemical communication

Caveolae

Invaginations in the cell surface of smooth muscle cells, store calcium ions