white-blood-cells

Your body contains roughly 5 liters of blood, and every drop of it completes a full circuit through the heart and lungs in about 60 seconds. Blood is not a simple liquid — it is a suspension of at least four distinct components performing oxygen transport, immune defense, wound sealing, and chemical delivery simultaneously. Here is how it all works.

The immune system is not a single organ or a single type of cell — it is a distributed surveillance network that distinguishes your own tissue from foreign invaders within minutes, then builds custom molecular weapons if the first response is not enough. Here is how.