Muscular System: Histology & Physiology

A collection of vocabulary flashcards based on the muscular system, focusing on histology, physiology, and key concepts.

Contractility

The ability of a muscle to shorten with force.

Excitability

The capacity of muscle to respond to a stimulus, usually from nerves.

Extensibility

The ability of muscle to be stretched beyond its normal resting length and still be able to contract.

Elasticity

The ability of muscle to recoil to its original resting length after being stretched.

Skeletal Muscle

Muscle attached to bones; responsible for voluntary movements like locomotion and posture.

Smooth Muscle

Muscle found in the walls of hollow organs and blood vessels; involuntary and autorhythmic in some places.

Cardiac Muscle

Muscle of the heart; autorhythmic and involuntarily controlled.

Neuromuscular Junction

The synapse or junction between a motor neuron and a muscle fiber, where excitation-contraction coupling occurs.

Action Potential

A rapid rise and subsequent fall in voltage or membrane potential across a cellular membrane.

Sliding Filament Model

The model that explains muscle contraction based on the sliding movement of actin and myosin filaments past each other.

Myofibrils

Rod-like structures within muscle fibers that contain sarcomeres, the contractile units of muscle.

Sarcomere

The basic functional unit of muscle fibers; the smallest part of a muscle that can contract.

T tubules

Inward folds of the sarcolemma that conduct action potentials deep into the muscle fiber.

Calmodulin

A protein that binds calcium ions and is involved in muscle contraction, particularly in smooth muscles.

Troponin

A protein complex involved in muscle contraction that binds to calcium and causes a conformational change, allowing interaction with myosin.

Tropomyosin

A protein that blocks the active sites on actin filaments; it is moved by troponin binding to calcium.

Myosin heads

Part of the thick filament that binds to actin and pulls during muscle contraction using energy from ATP.

Hypertrophy

An increase in muscle size due to an increase in the size of muscle fibers.

Atrophy

A decrease in muscle size or strength, often due to disuse or a health condition.

Treppe

The gradual increase in muscle contraction strength when a muscle is stimulated repeatedly.

Wave Summation

Increased muscle contraction force due to increasing frequency of stimulation before complete relaxation.

Tetanus

A state of smooth and continuous muscle contraction due to rapid stimulation.

Motor Unit

A single motor neuron and all the muscle fibers it innervates.

Isometric Contraction

Muscle contraction without a change in muscle length.

Isotonic Contraction

Muscle contraction with a change in muscle length, maintaining tension.

Slow-twitch Muscle Fibers (Type I)

Muscle fibers that contract slowly, have a better blood supply, more mitochondria, and are more fatigue-resistant.

Fast-twitch Muscle Fibers (Type II)

Muscle fibers that respond rapidly to stimulation and fatigue quickly; less efficient in oxygen use.

Duchenne Muscular Dystrophy (DMD)

A genetic disorder characterized by progressive muscle weakness and degeneration.

Oxygen Deficit

The lag time between the onset of exercise and the increased rate of breathing.