Skeletal Muscle: Structure and Function

This set of flashcards covers key concepts related to the structure and function of skeletal muscle, facilitating comprehension and study for exams.

Skeletal Muscle

Type of muscle tissue that is attached to bones and is involved in voluntary movements.

Endomysium

Connective tissue layer that wraps each individual muscle fiber.

Perimysium

Connective tissue layer that surrounds several muscle fibers and forms bundles called fasciculi.

Epimysium

Connective tissue that surrounds the entire muscle.

Sarcoplasm

Cytoplasm of a muscle fiber, containing myofibrils, organelles, and stored nutrients.

Myofibrils

Thread-like structures in muscle fibers that contain the contractile proteins actin and myosin.

Sarcomere

The basic functional unit of a muscle fiber, extending from one Z line to another.

Cross-bridges

Connections formed between actin and myosin filaments during muscle contraction.

Actin

Thin filament protein that plays a key role in muscle contraction.

Myosin

Thick filament protein that interacts with actin to cause muscle contraction.

Tropomyosin

Protein that wraps around actin filaments and regulates the binding of myosin.

Troponin

Complex of proteins that binds calcium ions and helps regulate muscle contraction.

Neuromuscular Junction

The synapse between a motor neuron and a muscle fiber, where nerve impulses trigger muscle contraction.

T-tubules

Transverse tubules that extend into the muscle fiber and help transmit the action potential.

Sarcoplasmic Reticulum (SR)

Network of tubules in muscle cells that stores calcium ions essential for contraction.

Type I Fibers

Slow-twitch muscle fibers characterized by low myosin ATPase activity and high fatigue resistance.

Type II Fibers

Fast-twitch muscle fibers with high myosin ATPase activity, suited for rapid and powerful contractions.

Sliding Filament Model

Theory explaining muscle contraction through the sliding movement of actin over myosin.

Calcium ions (Ca2+)

Key ions that bind to troponin and enable cross-bridge formation during muscle contraction.

ATP Hydrolysis

Process that releases energy, enabling the myosin heads to function during muscle contraction.