Skin, Skeletal, and Muscular Systems: Muscles in Action

The video tutorial explains how skeletal muscles enable movement by contracting and shortening in length. It describes how muscles work in pairs to move bones in opposite directions, using the arm as a model to illustrate the contraction of biceps and relaxation of triceps. The structure of skeletal muscle is detailed, highlighting muscle fibers, myofibrils, and filaments. The sliding filament theory is introduced, explaining how nerve impulses stimulate muscle contraction through the interaction of thin and thick filaments.

What is the primary function of skeletal muscles in the body?

• To store calcium

• To generate heat

• To move bones by contracting

• To produce hormones

Why do muscles often work in pairs?

• To maintain balance

• To increase strength

• To conserve energy

• To move bones in opposite directions

What are muscle fibers primarily composed of?

• Myofibrils

• Nerve cells

• Blood vessels

• Fat cells

Which structures within myofibrils are responsible for muscle contraction?

• Nuclei

• Cell membranes

• Mitochondria

• Thin and thick filaments

According to the sliding filament theory, what happens when a muscle is stimulated by a nerve impulse?

• The muscle elongates

• The thick filaments dissolve

• The thin filaments slide past the thick filaments

• The muscle becomes rigid