BackStudy Guide: Muscular System 2/4
Terms in this set (31)
Fascia is a layer of connective tissue that surrounds muscles, groups of muscles, blood vessels, and nerves, binding them together and providing support.
Perimysium is the connective tissue sheath that surrounds each muscle fascicle (a bundle of muscle fibers).
Epimysium is the dense connective tissue layer that surrounds the entire muscle.
Endomysium is the thin connective tissue layer that surrounds each individual muscle fiber.
A muscle compartment is a group of muscles enclosed by fascia, often sharing similar functions and nerve supply.
A muscle is an organ composed of muscle tissue, connective tissue, blood vessels, and nerves that produces force and movement.
A muscle fascicle is a bundle of muscle fibers surrounded by perimysium.
A muscle fiber is a single muscle cell, multinucleated and surrounded by endomysium.
Myofibrils are long, cylindrical organelles inside muscle fibers composed of repeating sarcomeres, responsible for contraction.
Myofilaments are the protein filaments (actin and myosin) that make up myofibrils and enable muscle contraction.
Satellite cells are muscle stem cells involved in growth, repair, and regeneration of muscle tissue.
Sarcoplasm is the cytoplasm of a muscle fiber, containing glycogen, mitochondria, and myoglobin.
Sarcolemma is the plasma membrane surrounding a muscle fiber, involved in conducting electrical impulses.
A sarcomere is the functional contractile unit of a myofibril, defined by Z-disks at each end.
T-tubules are invaginations of the sarcolemma that transmit action potentials deep into the muscle fiber.
Terminal cisternae are enlarged areas of the sarcoplasmic reticulum that store calcium ions near T-tubules.
Sarcoplasmic reticulum (S.R.) is a specialized smooth endoplasmic reticulum that stores and releases calcium ions for muscle contraction.
A triad consists of a T-tubule flanked by two terminal cisternae of the sarcoplasmic reticulum, coordinating calcium release.
Actin is the thin filament protein that interacts with myosin during muscle contraction.
Myosin is the thick filament protein with heads that bind to actin to generate contraction force.
Troponin is a regulatory protein on actin filaments that binds calcium to initiate contraction.
Tropomyosin is a regulatory protein that blocks myosin-binding sites on actin when muscle is relaxed.
Z-disks define the boundaries of a sarcomere and anchor thin filaments.
M-line is the central line of the sarcomere where thick filaments are anchored.
Titin is a large elastic protein that stabilizes thick filaments and contributes to muscle elasticity.
Dystrophin is a protein that links the cytoskeleton of muscle fibers to the extracellular matrix, providing structural support.
The I band is the light region of the sarcomere containing only thin filaments.
The A band is the dark region of the sarcomere containing the entire length of thick filaments.
The H zone is the central part of the A band where only thick filaments are present.
The zone of overlap is the region in the sarcomere where thick and thin filaments overlap.
The sliding filament theory explains muscle contraction as thin filaments sliding past thick filaments, shortening the sarcomere.