Human Immunity Non-specific Immunity
Non-Specific Immunity Non-specific = doesn’t distinguish between types of infectious agents Innate 1 st line of defense = skin and mucous membranes 2 nd line of defense Phagocytic cells Inflammation (Sign that 2 nd line is working) Complement system
1 st line – Skin and Mucous Membranes Physical barrier Low H2O content Secretions Sebum, sweat Stomach acid Bile, duodenal enzymes Lysozyme Normal microbiota (microbiome)microbiome
2 nd line – Phagocytosis *Limits spread of microbes in advance of specific response Leukocytes = white blood cells Neutrophils makes up 60-70% of leukocytes (chemotaxis) Monocytes make up 5% of leukocytes. Circulate in blood and then become macrophages in tissues. Macrophages engulf and digest with lysozyme in lysosomes. Process of phagocytosis Chemokines
Phagocytosis
2 nd line -- Inflammation Inflammatory response is an increased blood flow to the inured area resulting in leaking of fluid from capillaries into area causing swelling. Rubor, calor, tumor, dolor Triggered by chemical signals from invader or host cells. Basophils and mast cells release histamines. Pus
2 nd line -- Fever Can provide non-specific defense against disease Pyrogens Produced by macrophages Affect hypothalamus
2 nd line – Natural Killer Cells In blood and lymph Use receptors to tell healthy cells versus cells with cancer or virus Match with Class I MHC proteins (MHC = Major Histocompatibility Complex) If not match, damage membrane and induce cell lysis
2 nd line – Complement System
~30 proteins circulate in the blood and can be activated Cascade of signals and proteins binding and hydrolyzing… Classical Pathway - activated by the specific immune defense Alternative Pathway – C3 protein binding directly to pathogen Effects: Activates inflammatory response Acts as opsonin to increase phagocytosis (Opsonization) Activates cascade to trigger MACs (Membrane Attack Complexes) Large holes in membranes of gram – bacteria and enveloped viruses