The Sarcomere and Sliding Filament Theory

Muscle cells (also called muscle fibers)

are made of bundles of smaller fibers called myofibrils

The myofibrils consist of consecutive contraction units called

sarcomeres

Muscle cells (also called muscle fibers)

are made of bundles of smaller fibers called myofibrils

The myofibrils consist of consecutive contraction units called

sarcomeres

Thick filaments are made of a fibrous protein called

myosin

Thin filaments are made of a  protein called

actin

The H zone is the gap between the

thin filaments

thin filaments can

change size depending on if the sarcomere is contracted or relaxed

The A band is the area where _____ are

thick filaments

The A band is

always the length of the thick filaments

The I band is the area where the _____

thick filaments are NOT

The I band

can also change size depending on if the sarcomere is contracted or relaxed

When relaxed, the H zone is ____ than when contracted

larger

Thick filaments are made of ____ and have _____ heads on them

myosin