The Human Body [2021] | 360p | 8K |

[ Stimulus: Variable Rises ] ──► [ Receptor Detects Change ] ──► [ Control Center (Brain) ] │ [ Normal Level Restored ] ◄── [ Effector Responds ] ◄─────────────────────┘

Every movement you make – from blinking to running a marathon – requires coordinated muscle contractions. But muscles do more than move you; they also generate heat. When you shiver, skeletal muscles contract rapidly to warm the body. In fact, muscle activity accounts for roughly 25% of basal metabolic rate at rest and much more during exercise. The Human Body

Covers body surfaces, lines internal cavities, and forms glands, serving as a protective barrier and absorptive surface. [ Stimulus: Variable Rises ] ──► [ Receptor

Consisting of 206 bones in an adult, alongside cartilage, ligaments, and joints, the skeleton provides a rigid structural framework. It protects vital internal organs (such as the skull shielding the brain), acts as a lever system for movement, stores essential minerals like calcium, and houses bone marrow where all blood cells are produced. 3. The Muscular System In fact, muscle activity accounts for roughly 25%