what is human muscular structure ?

 The human muscular structure is made up of three types of muscles: skeletal, smooth, and cardiac. Skeletal muscles are the muscles that are attached to the bones and are responsible for voluntary movements, such as walking, running, and lifting weights. Smooth muscles are found in the walls of internal organs, such as the stomach, intestines, and blood vessels, and are responsible for involuntary movements, such as digestion and blood circulation. Cardiac muscle is found in the heart and is responsible for pumping blood throughout the body.

Skeletal muscles are made up of muscle fibers, which are long, cylindrical cells that are arranged in bundles. Each muscle fiber contains many myofibrils, which are the structures responsible for muscle contraction. The myofibrils contain proteins called actin and myosin, which interact to produce the force that causes muscle contraction.

Smooth muscles are made up of spindle-shaped cells that are not arranged in bundles. The cells contain actin and myosin filaments, but they are not organized in the same way as in skeletal muscles.

Cardiac muscle is similar to skeletal muscle in that it is composed of muscle fibers that contain actin and myosin filaments. However, cardiac muscle fibers are branched and interconnected, allowing them to work together to pump blood.