chapter 6

Skeletal Muscle

Voluntary muscles that attach to bones, appear striped (striated), and allow external movement.

Smooth Muscle

Involuntary muscles found within organs, blood vessels, and airways, that do not have a striped appearance.

Cardiac Muscle

Specialized, involuntary muscle found only in the heart that has a striated appearance.

Tendons

Fibrous tissues that attach skeletal muscles to bones.

Ligaments

Fibrous tissues that attach bone to bone.

Point of Origin

The end of a muscle that is attached to the stationary bone.

Point of Insertion

The muscle end attached to the moving bone.

Synergist

Muscles that assist the primary mover (agonist) in movement.

Antagonist

Muscles that cause movement in the opposite direction of the agonist.

Diaphragm

The primary mover of breathing, a dome-shaped muscle under both voluntary and involuntary control.

Vasodilation

The enlarging of the diameter of a blood vessel.

Vasoconstriction

The decreasing of the diameter of a blood vessel.

Sarcoplasm

The cytoplasm of a muscle fiber.

Sarcomere

The functional contractile unit of a muscle fiber, consisting of thick (myosin) and thin (actin) myofilaments.

Myofilaments

Threadlike structures in a sarcomere that are essential for muscle contraction.

ATP

Adenosine triphosphate; the energy source required for muscle contraction and relaxation.

Calcium Ion

An ion released during muscle contraction that causes actin and myosin to interact.

Electromyography

A diagnostic test that measures the strength of muscle contractions through electrical stimulation.

Myasthenia Gravis

A neuromuscular disorder characterized by gradually increasing muscle weakness.

Muscular Dystrophy

An inherited muscle disease causing progressive muscular weakness due to fiber degeneration.