Human Body
How the Skin Works: The Body's Largest Organ Explained
The skin covers roughly 1.7–2 square meters of surface area, weighs about 3.5–4 kg (making it the body's heaviest organ by mass), replaces its entire outer layer every 2–4 weeks, synthesizes vitamin D from sunlight, and detects pressure changes as small as 0.006 mm. Here is the full architecture.