02.03 Host defenses

Overview

1. Two main Types of Immunity in Vertebrates
   1. Innate- immune responses that an organism is born with
      1. Physical barriers such as skin, sweat, mucus, saliva, digestive enzymes, tears
      2. Inflammatory response- triggers increased blood flow, swelling, increase temp,
      3. White blood cells like mast cells secrete histamines, macropages start eating pathogens, neutrophils, basophils and eosinophils secrete toxins to bacteria/fungi and parasites, dendritic cells of the skin and mucousal lining link the innate to the adaptive immune system, Natural killer cells attack compromised or infected host cells.
   2. Adaptive- the immune response aka the aquired immune response is a very specific response to a particular pathogen.
      1. Pathogen-specific details are obtain and stored for the life of the organism.
      2. Macrophages (from innate system) that bind with the pathogen engulf it and present pieces on its membranes. This stimulates helper T cells to activate B cells to become plasma cells and make specific antibodies against the pathogen.
      3. Cells infected with the virus “present” fragents of the virus on their cell membranes.
      4. Helpter T cell that match these fragments (like a puzzle piece) are activated and release cytokines.
      5. These cytokines recruit and activate B cells and cytotoixc T cells with matching receptors (puzzle pieces)