Human Anatomy & Physiology

Immune System and Disease

An organism is protected from diseases by its immune system, which is a network of biological functions it can distinguish between the organism's own healthy tissue and a wide range of pathogens, such as viruses, parasitic worms cancer cells, and foreign things like wood splinters The immune system is divided into two main subsystems in many species. To a large variety of circumstances and stimuli the innate immune system offers a predefined reaction. By learning to recognise chemicals it has previously met, the adaptive immune system responds specifically to each stimulus Both rely on molecules and cells for their operations