Microscopic Anatomy of Skeletal Muscle p6

Flashcards covering key terms and concepts related to the microscopic anatomy of skeletal muscle and the sliding filament model.

Sarcolemma

The plasma membrane of a muscle fiber.

Sarcoplasm

The cytoplasm of a muscle fiber.

Myofibrils

Densely packed rodlike elements within a muscle fiber.

Sarcomere

The smallest contractile unit of a muscle fiber.

A bands

Dark regions in skeletal muscle where thick and thin filaments overlap.

I bands

Light regions in skeletal muscle that contain only thin filaments.

H zone

The lighter region in the middle of the A band.

Z disc (line)

A sheet of proteins in the midline of the I band that holds myofilaments in alignment.

Actin

A protein that makes up thin myofilaments.

Myosin

A protein that makes up thick myofilaments.

Cross bridges

Links formed between myosin heads and actin during muscle contraction.

Tropomyosin

A regulatory protein that blocks myosin binding sites on actin.

Troponin

A regulatory protein that has Ca2+ binding sites, helping to control muscle contraction.

Sarcoplasmic reticulum (SR)

A network that regulates intracellular Ca2+ levels in muscle fibers.

T tubules

Protrusions of the sarcolemma that allow electrical nerve transmissions to reach deep into each muscle fiber.

Sliding filament model

The theory that actin and myosin slide past each other during muscle contraction, resulting in sarcomere shortening.

Power stroke

The process where the myosin head pivots and pulls the actin filament toward the center of the sarcomere during contraction.