Foundations

How the human body is built up, from the smallest parts to the whole organism. Before looking at any single organ or life stage, it helps to understand the shared vocabulary and building blocks that everything else relies on.

This is the “how to read everything else” layer. Topics here are deliberately general — they apply across every organ system and every stage of life.

Contents

• Levels of organization — the ladder from atoms to the whole organism, and how each level emerges from the one below.
• Biomolecules — the chemical building blocks: water, proteins, carbohydrates, fats, and nucleic acids.
• Cells — the basic unit of life and the smallest thing that counts as “alive.”
• Tissues — the four fabrics the body is woven from.
• Anatomical terminology — the map and compass: directional terms, planes, and body regions.