Chapter 10.1-10.2- Muscle Cells

Three Classes of Muscle Tissue

Skeletal muscle tissue, Cardiac muscle tissue, Smooth muscle tissue

Striated Muscle Tissues

Skeletal and cardiac muscle tissues exhibit striations.

Sarco- Prefix

"Sarco-" means flesh or muscle.

Organelles Unique to Muscle Cells

Myofibrils, Sarcoplasmic reticulum, Transverse tubules (T-tubules)

Sarcolemma

The cell membrane of a skeletal muscle fiber, with invaginations called T-tubules.

Components of Skeletal Muscle Fiber Triad

Two terminal cisternae of the sarcoplasmic reticulum, A T-tubule

Myofibril

Cylindrical organelle in muscle cells, composed of actin and myosin filaments.

Types of Myofilaments

Thick filaments (myosin), Thin filaments (actin, troponin, tropomyosin), Elastic filaments (titin)

Sarcomere

Basic unit of a muscle, length determined between two Z-lines.

Arrangement of Myofilaments in a Sarcomere

Thin filaments anchored to Z-lines, Thick filaments in the center overlapping with thin filaments.

I-band and A-band

I-band contains only thin filaments, A-band contains both thick and thin filaments.

Striations

Alternating light-dark lines in a skeletal muscle fiber.

H-zone of a Sarcomere

Region in the center of the sarcomere with only thick filaments.

Changes During Muscle Contraction

I-band length decreases, A-band length remains constant, H-zone decreases or disappears as filaments slide past each other.