Biol+Sci+201+Ch+10

Skeletal Muscle

Allows for voluntary movement and is under conscious control.

Smooth Muscle

Found in the walls of hollow visceral organs and is involuntary.

Cardiac Muscle

Only found within the walls of the heart, responsible for pumping blood.

Epimysium

Dense irregular connective tissue that surrounds the whole muscle.

Fascicles

Bundles of muscle fibers wrapped by perimysium.

Endomysium

Connective tissue that surrounds individual muscle fibers.

Myofibrils

Contractile elements of muscle fibers.

Sarcomere

Functional unit of muscle contraction; extends from Z disc to Z disc.

A band

Dark band in the myofibril that contains thick myosin filaments.

I band

Light band in the myofibril containing only thin actin filaments.

Titin

Largest protein in the body that stabilizes thick filaments and provides elasticity.

Neuromuscular Junction

The site where a motor neuron communicates with a muscle fiber.

Acetylcholine

Neurotransmitter released at the neuromuscular junction to trigger muscle contraction.

Concentric Contraction

Muscle shortens and causes movement.

Eccentric Contraction

Muscle lengthens while producing force.

Origin

Bony site of attachment that remains more stationary during contraction.

Insertion

Bony site of attachment that is more mobile during contraction.

Slow-oxidative fibers (SO)

Thin red muscle fibers rich in myoglobin; suited for endurance.

Fast-glycolytic fibers (FG)

Thick white muscle fibers; rely on glycolysis and provide fast, powerful contractions.

Muscular Dystrophy

Inherited disorder characterized by the replacement of muscle tissue with fat and connective tissue.