The Human Body Jun 2026

At the most microscopic level, the human body is composed of approximately 30 to 37 trillion cells. Cells are the fundamental units of life, specialized to perform distinct functions.

Protects the body against infections and diseases. Maintaining the Machine: Care and Longevity The Human Body

The circulatory system is the body’s primary transport network, powered by the heart. The heart acts as a dual pump, pushing blood through a vast network of blood vessels that stretches roughly 60,000 miles if laid end-to-end. Arteries carry oxygen-rich blood away from the heart to the rest of the body, where microscopic capillaries exchange nutrients and oxygen for carbon dioxide and waste. Veins then collect this deoxygenated blood and return it to the heart and lungs to restart the cycle. The Respiratory System At the most microscopic level, the human body

These systems manage nutrient intake, waste removal, and protection. Maintaining the Machine: Care and Longevity The circulatory

Scientists typically divide the body into that carry out specific functions:

Operating via electrical impulses, the nervous system acts as the body's high-speed communication network. It is split into the Central Nervous System (the brain and spinal cord) and the Peripheral Nervous System (the nerves branching throughout the body). The brain processes sensory data, stores memories, regulates basic life functions, and generates conscious thought. The Endocrine System