Cellular

The cell is the fundamental unit of biology — the smallest structure that grows, replicates, responds to environment, and dies by program or accident. The human body maintains 37.2 trillion of them simultaneously: immune cells patrolling for pathogens and tumors, cardiomyocytes firing 100,000 times a day for a lifetime, neurons holding synaptic weights that encode memory, hepatocytes performing thousands of metabolic reactions per second. Each cell type in the atlas is modeled with its origin, defining proteins, signaling state, functional role, failure modes, and connections to the molecules below and the tissues above it.