ch. 17 innate nonspecific host defenses

• physical barriers


  Skin: Outermost layer, epidermis, keratin, prevents pathogen entry.Mucous Membranes: Produce mucus, trap and remove pathogens.Cilia: Hair-like structures, respiratory tract, sweep mucus and pathogens out.
• innate immunity


  a host response that is immediate to an invader
• adaptive immunity


  a host response that is developed over time to be specific to an invader
• microbiome


  the collection of microorganisms that grow on or in an individual
• tight junctions, desmosomes, gap junctions


  The three animal cell junctions
• tight junctions


  Membranes of neighboring cells are pressed together, preventing leakage of extracellular fluid

  
• Desosomes


  have intermediate fibers that act like shoelaces, tying two cells together, allowing small materials to pass through

  
• gap junctions


  (communicating junctions) provide cytoplasmic channels between adjacent cells

  
• layers of skin


  epidermis- dead skin cells and oil

  dermis - hair follicles and glands

  hypodermis - fat and blood vessels

  
• endothelia


  The epithelial cells lining the urogenital tract, blood vessels, lymphatic vessels, and certain other tissues
• mechanical defenses


  Coughing and Sneezing:Expel pathogens from respiratory tract.Mucociliary Escalator: Cilia and mucus movement transport pathogens.vomiting, diarrhea, etc
• microbiome


  normal microbes that grow on and in you protect you from new pathogenic growth

  Skin Microbiota: Compete with pathogens on skin surface.Gut Microbiota: Promote gut homeostasis, nutrient absorption.
• Enzymes in Body Fluids and Innate Immunity

  Lysozyme: Breaks down bacterial cell walls, found in tears, saliva, and mucus.Lactoferrin: Sequesters iron, hindering microbial growth; found in saliva and mucus.Acidic pH: Denatures microbial proteins, found in gastric acid, and when sebum is used as a food source to produce olic acid, contributes to pathogen neutralization.
• How lysozyme works


  Breaks bonds in peptidoglycan wall

  Water potential is lower in the cell, so water continuously moves in.

  Cell swells and the wall bursts.

  Cell eventually bursts.
• innate immune factors found in plasma

  acute-phase proteins, complement, cytokines (signal molecules)
• acute phase proteins


  Produced during inflammation

  Examples: C-reactive protein (CRP), serum amyloid A (SAA)

  Enhance immune response

  Regulate inflammation

  Promote tissue repair and healing

  
• Three complement activation pathways


  classical, lectin, alternative
• complement: Classical activation pathway

  C1q is activated by antibody
• complement: lectin activation pathway


  triggered by the binding of mannose-binding lectin to carbohydrates on the microbial surface
• complement: alternative activation pathway

  activated by complement component binding directly to surface of target cell, creates MAC (membran attack complex), forming a pore in the pathogen membrane and killing the cell
• Function of antimicrobial peptides

  inhibit cell wall synthesis and form pores in the plasma membrane
• Cytokines


  autocrine, paracrine, and endocrine
• Autocrine


  secretes and receives cytokine signal

  
• paracrine


  cytokine signal secreted to a different cell

  
• endorcrine


  cytokine signal secreted to circulatory system, travels to distant cells
• Interferons


  proteins (cytokines) secreted by T cells and other cells to aid and regulate the immune response

  
• inflammation mediators

  histamine- causes vasodilation (widening of blood vessels), increased vascular permeability (leakiness of blood vessels), and contraction of smooth muscleleukotrienes- may induce coughing, vomiting, and diarrhea (to expel the pathogens)bradykinin- may lead to edema (where fluid leaves the bloodstream and enters infected tissues, also stimulates the release of pain mediators
• cellular defense: RBCs


  erythrocytes
• cellular defense: platelets


  thrombocytes
• cellular defense: WBCs


  leukocytes
• Hematopoiesis


  blood cell formation, stem cells grow in blood marrow
• Pluripotent


  Cells that are capable of developing into most, but not all, of the body's cell types
• Lymphocytes


  white blood cells
• Phagocytes


  can phagocytose foreign material/pathogens

  -Neutrophilss and monocytes
• granulocytes


  neutrophils, eosinophils, basophils
• Neutrophils


  help eliminate and destroy extracellular bacteria, can migrate to infected tissue and kill the bacteria with their granules that have defensins and hydrolytic enzymes (kill bact. through phagocytosis), they trap invader in NETs (neutrophile extracellular traps) where they release their chromatin and antimicrobial peptides.