Muscular System Overview

These flashcards cover key terms and concepts from the muscular system chapter, including definitions related to muscle structure, contraction processes, and types of muscle fibers.

Action potential

An electrical signal that travels along a nerve fiber.

Acetylcholine

A neurotransmitter released into the synaptic space that binds to muscle receptors.

Sarcoplasmic reticulum

A specialized endoplasmic reticulum in muscle cells that stores calcium ions.

Sarcomere

The basic contractile unit of muscle fibers.

Myofibril

A long cylindrical structure made of myofilaments; it's the contractile element in muscle fibers.

Troponin

A protein that binds calcium ions and helps regulate muscle contraction.

Tropomyosin

A protein that blocks myosin binding sites on actin filaments at rest.

Thick filament

Composed primarily of myosin proteins; these filaments interact with thin filaments to produce muscle contractions.

Thin filament

Composed primarily of actin, along with troponin and tropomyosin; involved in muscle contraction.

Z line

The boundary of a sarcomere; attaches thin filaments.

Tendon

A cordlike extension of fascia that connects muscle to bone.

Aponeurosis

A sheet-like extension of fascia connecting muscle to bones or other muscles.

Epimysium

The layer of connective tissue that surrounds an entire skeletal muscle.

Perimysium

The connective tissue layer surrounding a fascicle (bundle of muscle fibers).

Endomysium

The layer of connective tissue surrounding individual muscle fibers.

Excitation-Contraction Coupling

The process through which an action potential in a muscle fiber leads to contraction.

Sliding Filament Model

Describes how muscle fibers contract through the sliding of actin over myosin.

Energy Sources for Contraction

Include ATP and creatine phosphate used to fuel muscle contractions.

Oxygen Debt

The amount of oxygen needed post-exercise to restore muscle to its resting state.

Isotonic contraction

A type of muscle contraction where the muscle changes length while maintaining tension.

Isometric contraction

A type of contraction where the muscle stays the same length while tension increases.

Fast-twitch fibers

Muscle fibers that are anaerobic and provide explosive power but fatigue easily.

Slow-twitch fibers

Muscle fibers that are aerobic, providing steady power and endurance.

Neuromuscular junction

The synapse between a motor neuron and a muscle fiber, allowing for communication that triggers contraction.