BIOL 225 Chapter Notes - Chapter 43: Autoimmune Disease, Intron, Antigen Presentation
Document Summary
Innate immunity: a defense that is active immediately upon infection and is the same whether or not the pathogen has been encountered previously. Adaptive immunity: a defense found only in vertebrates. Mucous membranes lining the digestive, respiratory, urinary and reproductive tracts. Body secretions create an environment that is hostile to many microbes. Phagocytic cells detect fungal or bacterial components using several types of receptors (binds to fragments of molecules characteristic of a set of pathogens). After detecting invading pathogens, a phagocytic cell engulfs them, trapping them in a vacuole. Neutrophils: circulate in blood, are attracted by signals from infected tissues and then engulf and destroy the infecting pathogens. Macrophages: some migrate throughout the body, whereas others reside permanently in organs and tissues where they are likely to encounter pathogens. Dendritic cells: mainly populate tissues, such as skin, that contact the environment. Eosinophils: often found beneath mucosal surfaces, have low phagocytic activity but are important in defending against multicellular invaders.
