Muscular, Nervous and Skeletal Systems (Video) - Vocabulary Flashcards

Vocabulary flashcards covering key terms from the Muscular, Nervous, and Skeletal lecture notes.

Skeletal muscle

A type of muscle tissue that attaches to bones and causes movement by creating rotation around joints.

Epimysium

Connective tissue that surrounds the entire skeletal muscle.

Perimysium

Connective tissue that surrounds each fascicle (bundle of muscle fibers) within a muscle.

Endomysium

Connective tissue that surrounds individual muscle fibers.

Fascicle

A bundle of muscle fibers within a muscle.

Muscle fiber

A single muscle cell contained within a fascicle; contains myofibrils and other organelles.

Myofibril

A bundle of myofilaments running parallel to the length of a muscle fiber.

Myofilaments

Actin (thin) and myosin (thick) filaments that slide past each other during contraction.

Sarcolemma

The plasma membrane of a muscle fiber; conducts action potentials.

Sarcoplasm

Cytoplasm of a muscle fiber containing energy sources for contraction.

Mitochondria

Organelles that produce ATP via aerobic metabolism in muscle cells.

Sarcoplasmic reticulum (SR)

An organelle that stores and releases calcium for muscle contraction.

T-tubules

Transverse tubules that transmit the action potential from the sarcolemma into the muscle fiber.

Actin

Thin filament in a muscle fiber involved in the cross-bridge cycle.

Myosin

Thick filament with heads that bind to actin to generate contraction.

Troponin

Calcium-binding protein that moves tropomyosin to expose myosin-binding sites on actin.

Tropomyosin

Regulatory protein that blocks myosin-binding sites on actin at rest.

Sarcomere

The functional, contractile unit of skeletal muscle from Z-line to Z-line.

Z-line

Boundary lines of a sarcomere to which actin filaments anchor.

A-band

Dark region of the sarcomere that contains thick filaments (myosin) and overlap with actin.

I-band

Light region containing only thin filaments (actin); shortens during contraction.

H-zone

Region within the A-band that contains only thick filaments; disappears during contraction.

M-line

Center of the sarcomere where thick filaments are anchored.

Sliding Filament Theory

The model in which actin and myosin filaments slide past one another, shortening the sarcomere without changing filament length.

Neuromuscular Junction (NMJ)

Specialized region where a motor neuron communicates with a skeletal muscle fiber.

Acetylcholine (ACh)

Neurotransmitter released at the NMJ to stimulate muscle contraction.

Excitation-contraction coupling

Process from motor neuron activation to cross-bridge formation and muscle contraction.

Motor unit

A motor neuron and all the muscle fibers it innervates; all fibers in a unit are the same type.

Motor unit recruitment

Activation of additional motor units to increase muscle force.

Rate coding

Increasing the firing rate of already active motor units to raise force output.

Type I fibers

Slow-twitch, oxidative fibers with high endurance and many mitochondria.

Type IIa fibers

Fast oxidative glycolytic fibers with intermediate endurance and speed.

Type IIx fibers

Fast glycolytic fibers with high power but rapid fatigue.

Concentric contraction

Muscle shortens as it generates force against resistance.

Eccentric contraction

Muscle lengthens while producing force against resistance.

Isometric contraction

Muscle generates force without changing length (static hold).

DOMS (Delayed Onset Muscle Soreness)

Soreness after exercise due to microscopic tears in connective and muscle tissue; not primarily lactic acid.?

Skeletal System

System of bones and joints that provides structure, protection, and supports movement.

Axial skeleton

Skull, vertebral column, sternum, and ribs.

Appendicular skeleton

Bones of the limbs (arms and legs) and their girdles.

Bone remodeling

Continuous process of bone resorption by osteoclasts and formation by osteoblasts.

Osteoporosis

Condition of low bone mineral density, increasing fracture risk.

Peak bone mass

Highest attainable bone density, typically reached around age 20.

Wolf's Law

Bone adapts its structure to the mechanical stresses placed on it.

Tendons

Connect muscle to bone; composed mainly of collagen and withstand tensile forces.

Ligaments

Connect bone to bone; contain collagen and elastin to allow stability and mobility.

Bone mineral density (BMD)

Measure of bone density used to diagnose osteoporosis and fracture risk.

Calcium

Mineral essential for muscle contraction and bone health; released from the SR during contraction.

Golgi tendon organ

Sensory receptor that detects excessive muscle tension to protect the muscle.

Muscle spindle

Sensory receptor within muscle that detects changes in muscle length (stretch).