Muscular System Notes: types

Muscular system

Body system responsible for movement of the body and its parts and for generating heat.

Muscle contraction

Shortening of muscle cells that produces movement and heat.

Skeletal muscle

Striated, voluntary muscle attached primarily to bones.

Skeletal muscle percentage

Makes up about 40–50% of total body weight.

Striations

Microscopic stripes visible in skeletal muscle fibers.

Multinucleate

Having more than one nucleus per cell (skeletal muscle).

Voluntary control

Muscle contraction controlled consciously by the nervous system.

Skeletal muscle contraction speed

Slow to fast and nonrhythmic.

Cardiac muscle

Involuntary muscle tissue found only in the heart.

Branching cells

Cardiac muscle cells branch frequently.

Uninucleate

Having one nucleus per cell (cardiac muscle).

Intercalated discs

Dark bands that connect cardiac muscle cells and allow coordinated contraction.

Cardiac muscle control

Controlled by nervous system and hormones.

Cardiac muscle contraction

Rhythmic and normally slow.

Smooth muscle

Nonstriated, involuntary muscle found in visceral organs.

Nonstriated muscle

Muscle lacking visible stripes.

Fusiform cells

Spindle-shaped cells that taper at both ends.

Smooth muscle locations

Walls of digestive tract, blood vessels, and ureters.

Smooth muscle control

Not under voluntary control.

Muscle fiber

Another name for a muscle cell; also called a contractile cell.

Fascicle

Bundle of muscle fibers grouped together.

Myofilaments

Protein filaments within muscle fibers responsible for contraction.

Myosin

Thick myofilament involved in muscle contraction.

Actin

Thin myofilament involved in muscle contraction.

Sarcomere

Basic functional (contractile) unit of a muscle fiber.

Z-lines

Dark bands that separate sarcomeres.

Skeletal muscle organ

Composed of skeletal muscle cells and connective tissue.

Endomysium

Connective tissue that surrounds each muscle fiber.

Perimysium

Connective tissue that surrounds bundles of muscle fibers (fascicles).

Epimysium

Connective tissue that surrounds the entire muscle.

Origin

Attachment point of a muscle to the bone that remains relatively stationary during contraction.

Insertion

Attachment point of a muscle to the bone that moves during contraction.

Muscle belly (body)

Thick, central part of a muscle.

Tendon

Cord-like connective tissue that attaches muscle to bone.