Bio (class of doom and despair)

How is skeletal muscle organized from the whole organ to its smallest filaments?

Whole muscle → fascicles → muscle fibers → myofibrils → myofilaments.

What is a whole skeletal muscle, such as the biceps brachii?

An organ containing bundles of muscle fibers, connective tissue, nerves, and blood vessels.

What is a skeletal muscle fascicle?

A bundle of muscle fibers enclosed by perimysium, a connective tissue layer.

What does muscle fiber mean in skeletal muscle tissue?

A single long muscle cell that contains many myofibrils.

What is a myofibril?

A long contractile structure inside a muscle fiber, made of repeating sarcomeres.

What are myofilaments in a skeletal muscle fiber?

The protein filaments within myofibrils: thin filaments containing actin and thick filaments made of myosin.

How do a muscle fiber and a myofibril differ?

A muscle fiber is an entire cell; a myofibril is a contractile structure inside that cell.

How do a myofibril and a myofilament differ?

A myofibril contains organized thin and thick myofilaments arranged into repeating sarcomeres.

A muscle sample contains a bundle of many muscle cells wrapped together. What level of organization is described?

A fascicle, because it is a bundle of muscle fibers.

Why does a skeletal muscle fiber contain many myofibrils?

Their coordinated contractile activity allows the muscle fiber to generate force.