Once the nutrients are absorbed, the (including the kidneys and bladder) filters the blood to remove waste and maintain the body’s delicate water and salt balance. 5. The Invisible Shield: The Immune System
The human body requires fuel to function. The breaks down food into glucose, amino acids, and fats. This process begins in the mouth and involves a complex chemical journey through the stomach and intestines. The Human Body
Powered by the heart—a muscle that pumps about 2,000 gallons of blood daily—this system uses a 60,000-mile network of vessels to transport life-sustaining fluid. Once the nutrients are absorbed, the (including the