Immune Response

Innate immunity is the fast, non-specific first line of defense. It includes physical barriers (skin, mucous membranes), and immune cells like neutrophils and macrophages that quickly attack anything recognized as foreign.

Adaptive immunity is slower but highly specific. It learns to recognize particular threats and mounts a targeted response using:

B cells – produce antibodies that neutralize pathogens
T cells – directly kill infected cells or coordinate the immune response
Memory cells – "remember" past invaders so future responses are faster and stronger (the basis of vaccination)