Human Body: Muscular System

1) Smooth Muscle 2) Cardiac Muscle 3) Skeletal Muscle

Muscle that contracts automatically and are involuntary

Muscle that makes up the heart

Muscle that is connected by bones and tendons

Connective tissue that surrounds each bundle of muscle fibers and outside every muscle; runs throughout the entire body

Connective tissue that connects muscle to bone

Connective tissue that connects bone to bone

Sliding Filament Theory

Thick filament of protein that catches on actin when a muscle contracts

Thin filament of protein that catches on myosin when a muscle contracts

1) Calcium levels in the muscle increase. 2) Electrical impulses travel from the brain to the muscle. 3) The protein filaments, myosin and actin, slide over each other, catching & holding like Velcro.

1) Calcium levels in the muscle drop. 2) Electrical impulses travel from the brain to the muscle. 3) The protein filaments, myosin & actin, release and slide over each other back to nearly their resting position.

Type of contraction where the ends of the muscle come closer together; muscle shortens when working

Type of contraction where the ends of the muscle move farther apart; muscle lenthens when working

Type of contraction where muscle is working but doesn’t move position; muscle stays same length when working