Muscular System & Contraction Flashcards

Practice flashcards covering the functions, properties, structure, and contraction mechanism of the muscular system based on lecture notes.

Movement

The primary function of the muscular system.

Body Stabilization/Posture

A function of the muscular system where muscles fire to keep the body upright and maintain posture.

Regulate Organ Volume

A function of the muscular system primarily performed by smooth muscle in hollow organs like the stomach and intestines.

Thermogenesis

The process of generating heat, such as through shivering, by muscle contraction.

Protection (Muscular System)

A function of the muscular system where muscles cover body cavities, especially the soft organs of the abdominal cavity.

Skeletal Muscle

Muscle tissue that is striated (striped) and voluntary (controlled by conscious thought).

Smooth Muscle

Muscle tissue that is non-striated (no stripes), involuntary, and found in hollow organs like the stomach, gallbladder, intestines, uterus, and bladder.

Contractility

The ability of a muscle to contract or shorten, which is what causes movement.

Conductivity

The ability of muscle tissues to conduct an electrical impulse, also known as an action potential.

Excitability

The ability of muscles to be excited or stimulated by a nerve impulse or action potential.

Extensibility

The ability of a muscle to extend, stretch, or lengthen.

Elasticity

The ability of a muscle to return to its original shape after being stretched.

Myosin

A contractile protein that forms thick filaments in muscle, shaped like a golf club, whose heads bind to actin.

Actin

A contractile protein that forms thin filaments in muscle, described as looking like 'olives on a string', containing binding sites for myosin heads.

Titin

A structural protein, described as a coiled spring, that runs through the sarcomere.

Troponin

A regulatory protein that, along with tropomyosin, covers binding sites on actin in a resting muscle and binds with calcium during contraction.

Tropomyosin

A regulatory protein that, along with troponin, covers the binding sites on actin filaments in a resting muscle.

Sarcomere

The functional unit of muscle contraction, defined as the area between two Z-discs.

Binding Site (Muscle Contraction)

Specific locations on actin filaments where myosin heads connect during muscle contraction.

Crossbridge

The connection formed when a myosin head binds to a binding site on actin.

Action Potential

An electrical impulse or message that tells a muscle to contract.

Depolarization

The process where sodium rushes into a cell, causing a change in the membrane potential.

Repolarization

The process of pumping sodium back out and potassium back into a cell, resetting it after depolarization.

Sarcoplasmic Reticulum

A specialized endoplasmic reticulum within muscle cells that stores calcium.

T-tubule

Invaginations (dips) of the muscle fiber membrane that conduct action potentials deep into the muscle cell.

ATP

Adenosine Triphosphate, the energy molecule required for both muscle contraction (energizing myosin heads) and relaxation (detachment).

Power Stroke

The step in muscle contraction where the energized myosin head pivots, pulling the thin filament and causing the muscle to shorten.

All or None Principle

The concept that an individual muscle fiber will contract either completely or not at all.

Fasciculation

A small, involuntary muscle twitch; a partial contraction of a bundle of muscle cells, not a full muscle contraction.

Neuromuscular Junction

The specialized space where a nerve and a muscle fiber come very close together to transmit an electrical impulse.

Sliding Filament Theory

A theory stating that muscle contraction occurs as actin filaments slide over myosin filaments, trying to meet in the middle.

Epimysium

The connective tissue covering that wraps around the entire muscle.

Perimysium

The connective tissue covering that bundles muscle cells into a fascicle.

Endomysium

The protective coating that wraps around each individual muscle cell.

Fascicle (Muscle)

A bundle of muscle cells wrapped in perimysium.

Muscle Belly

The main, central, and often thickest portion of a muscle.

Origin (Muscle)

The end of a muscle that typically remains relatively stationary or fixed during contraction.

Insertion (Muscle)

The end of a muscle that moves toward the origin during contraction.

Carbo Loading

A strategy used by athletes to consume high amounts of carbohydrates before an event to maximize energy reserves.