Immune System and Disease
Science

Immunity given by antibodies made by the immune system, in response to an antigen
Active immunity
Immunity given by antibodies made by the immune system, in response to an antigen. Active immunity. Active immunity is when your body learns to defend itself by making its own antibodies after being exposed to a disease.

A chemical that increases the flow of blood and fluids, it is secreted by mast cells
Histamine
A chemical that increases the flow of blood and fluids, it is secreted by mast cells. Histamine. Histamine is a natural chemical in the body that helps fight allergies by causing symptoms like sneezing and itching.

A disease that is spread by pathogens, from an infected organism or the environment
Infectious disease
A disease that is spread by pathogens, from an infected organism or the environment. Infectious disease. An infectious disease is an illness caused by germs that spread from person to person or through the environment.