Muscle Contraction Overview

These flashcards cover key vocabulary related to muscle contraction and its regulation.

Skeletal Muscle

The type of muscle that is under voluntary control and is attached to bones, allowing for movement.

Smooth Muscle

Involuntary muscle found in internal organs, such as the stomach and intestines.

Cardiac Muscle

Involuntary muscle found only in the heart.

Sarcolemma

The plasma membrane of a muscle cell.

Sarcoplasm

The cytoplasm of a muscle cell.

Myofibrils

Structures inside a muscle cell that contain the filaments responsible for contraction.

Thin Filaments

Filaments made primarily of actin found in muscle fibers.

Thick Filaments

Filaments made up of myosin that interact with actin during muscle contraction.

Sarcomere

The repeating unit of a muscle fiber that contains thin and thick filaments.

Actin

A globular protein that forms the thin filaments in muscle cells.

Myosin

A protein that forms the thick filaments and interacts with actin to cause muscle contraction.

Tropomyosin

A protein that wraps around actin filaments and blocks the binding sites for myosin.

Troponin

A protein complex that binds calcium and causes tropomyosin to move, allowing myosin to bind actin.

Calcium (Ca2+)

An ion necessary for muscle contraction, which binds to troponin and allows contraction to occur.

ATP

A molecule that provides energy for muscle contractions and is necessary for myosin to release from actin.

Motor Unit

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

Neuromuscular Junction

The synapse between a motor neuron and a muscle fiber that allows for muscle contraction.

Sarcoplasmic Reticulum

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

Rigor Mortis

The stiffness of muscles after death due to the lack of ATP, causing myosin heads to remain bound to actin.

Action Potential

An electrical signal that triggers muscle contraction by causing the release of calcium from the sarcoplasmic reticulum.

Muscle Fiber

A single muscle cell that is capable of contraction.