Lecture 7: Innate ImmunityOverview of the Body’s Defenses- Resistance to most plant and animal pathogenso Species resistance Due to physiological processes of humans that are incompatible withthose of the pathogen- Correct chemical receptors not present on human cells- Conditions may be incompatible with those needed for pathogen’s survival- Immune system-o protect against cancerous cells, pathogens, toxins, and dead cells or pollutiono protects us from a variety of human pathogenic agents;- General Mechanisms of the immune system:A. Nonspecific mechanisms (innate Immunity) Rapid response within hours Fixed Limited number of specificities Constant during responseB. Specific Mechanism (Adaptive/Acquired Immunity)  Slow response within days to weeks Variable Numerous highly selective specificities Improve during response (through memory cells)Innate and Acquired (Adaptive) Immunity: common effector mechanisms for the destruction of pathogens Innate Immunity- First line of Defense - Phagocytosis - Inflammation- Complement Adaptive (acquired) Immunity - Humoral Immunity - Cell-mediated Immunity - Antigen Processing and PresentationThe Body First Line of Defenses- Structures, Chemicals, and processes that work to prevent pathogens entering the body o Skino Mucous membranes of the respiratory, digestive, urinary, and reproductive systemsBody First Line of Defense: Skin- The Role of Skin in Innate Immunityo Epidermis (Outer Layer of the Skin) Multiple layer of tightly packed cells Few pathogens can penetrate these layers Shedding of dead skin cells remove microorganisms Epidermal dendritic cells phagocytize pathogens o Dermis (Inner layer of the skin) Collagen fibers help skin resist  Skin has chemicals that defend against pathogenso Perspiration secreted by sweat glands Salt inhibits growth of pathogens  Antimicrobial peptides act against microorganisms  Lysozyme destroys cell wall of Gram (+) bacteriao Sebum secrete by sebaceous(oil) glands  Helps keep skin pliable and less likely to break or tear  Lowers Skin pH to a level inhibitory to many bacteria Body First Line of Defense: Mucous Membraneso Mucous membranes line all body cavities open to environmento Two distinct layer o Thin, outer covering of mucous membraneo Epithelial cells are livingo Tightly packed to prevent entry of pathogenso Continual shedding of cells carries away microorganismo Deeper Connective layer that supports the epithelium o Structures of respiratory system are lined with mucous membrane (ciliated epithelium) Body’s First Line of Defense o Lacrimal Apparatus o Produces and drains tearso Blinking spreads tears and washes surface of the eyeo Lysozyme in tears destroys gram (+) bacteria o Normal Microbiota in Innate Immunity o Microbial Antagonism Normal microbiota competes with potential pathogens o Activates of normal Microbiota make it hard for pathogens to compete Consumption of nutrients  Create an environment unfavorable to other microorganisms Help stimulate the body’s second line of defense  Promote overall health by providing vitamins to host Other First Line of Defense o Antimicrobial Peptides o Present in skin, mucous membranes neutrophilso Act against a variety of microbes o Works in several ways (The modes of action by antimicrobial peptides) Inducing holes in bacterial membranes  Intracellular killing o Others Process and chemicalo Many organs secrete chemical with antimicrobial properties The Body’s second Line of Defense o Operates when pathogen penetrates the skin or mucous membrane o Composed of cells, antimicrobial chemicals  Many of these components are contained or originate in the blood- Phagocytic cells (Blood and Tissues)- Nonspecific Chemical Defense Against Pathogens - Complement proteins (serum)- Antimicrobial peptides (all body secretions)- Interferons (3 types)- Inflammation  Fevero Defense Components of Blood o Plasma Mostly water containing electrolytes, dissolved gases, nutrients, and proteins o Serum  Fluid remaining when clotting factors are removed Includes iron-binding compounds, complement proteins and antibodies o Defense Component of Blood o Cells and cell fragments in plasma are called formed elementso Three Types of Formed Elements (Blood Cells and Plateletso Erythrocytes Carry oxygen and carbon dioxide in the blood o Platelets Involved in blood clottingo Leukocytes(WBC) Involved in defending the body against invaders Divided into granulocytes and agranulocytes Schematic Representation of Hematopoiesis - Hematopoiesis: refers to the formation and development of the cells of the bloodo Hematopoietic Pluripotent cells  Common Myeloid progenitor cells(CMP)- Erythrocyte- Megakaryocyte- Neutrophil- Eosinophil- Basophil- Monocyteo macrophage Common Lymphoid progenitor cells (CLP)- B-Cell- T-Cell- NK- CellCells of Human Blood - Blood Stem Cell in Bone Marrow o Erythroid Stem Cell (Gas transportation) Erythrocyteo Myeloid Stem Cell (Innate Immunity, Second line of defense) Platelets: Clotting, Inflammation Basophil: Inflammation Neutrophil Eosinophil: Phagocytosis Monocyteo Lymphoid Stem Cell (Adaptive immunity)  Lymphocyte Defense Components of Blood - Granulocytes: contains large granules that stains different colorso Three Types Basophils: stains blue with basic dye methylene blue Eosinophils: stains red/orange with acidic eosin Neutrophils- stain lilac with mix of acidic and basic dyeso Neutrophils and eosinophils - Phagocytize pathogens- Capable of diapedesis (Chemotaxis)- Agranulocytes o Cytoplasm appears uniform under a light microscope o Two Types Lymphocytes - Most involved in adaptive immunity  Monocytes - Leave the blood and mature into macrophages White Blood Cells (WBC): Never Lets Monkey Eat Babies (Most abundant to least) o Neutrophil (60)o Lymphocytes (30)o Monocyte (6)o Eosinophils (3)o Basophils (1)The Body’s Second Line of Defense Defense Components of Blood o Lab Analysis of Leukocytes (WBC)o Differential White Blood Cell count can signal signs of disease  Increased eosinophils indicate allergies or parasites worm infection Bacterial disease often show increase in leukocytes which are mostlyneutrophils o Phagocytosis o Cells capable of phagocytosis are called phagocyteso Phagocytosis is not completely understoodo Can be divided into six stages o Chemotaxiso Adherenceo Ingestion (In