Micropara: immunity

• Immune System


  Protects our body from infection with layered defenses
• Types of Immune Responses


  • Innate Immune System (Nonspecific Defenses)
  • Adaptive Immune Response (Specific and Acquired)
• Innate Immune System


  • Response is non-specific
  • Exposure leads to immediate maximal response
  • No cell-mediated and humoral components
  • No immunological memory
  • Found in nearly all forms of life
• Adaptive Immune Response


  • Pathogen and antigen specific response
  • Lag time between exposure and maximal response
  • Has cell-mediated and humoral components
  • Exposure leads to immunological memory
  • Found only in jawed vertebrates
• Nonspecific Defenses


  Defense against any pathogen, regardless of species
• Specific Defenses


  Defense against a specific pathogen
• Mechanical Factors


  Barriers (intact skin) to entry or processes that remove microbes from the body's surface
• Chemical Factors


  Substances made by the body that inhibit microbial growth or destroy them
• First Line of Defense - Mechanical Factors


  • Intact Skin
  • Mucous Membrane
  • Fluid Flow
• First Line of Defense - Chemical Factors


  • Sebum
  • Perspiration
  • Lysozyme
  • Gastric Juice
  • Transferrins
• Normal Microbiota


  Microorganisms that colonize a host without causing disease
• Normal Microbiota


  • Prevents the overgrowth of pathogens by competing with them for nutrients
  • Produces substances harmful to pathogens (bacteriocins)
• Phagocytosis


  Ingestion of a microorganism or other particles such as debris by a cell (performed by a type of white blood cell "phagocytes")

  
• Types of Phagocytes


  • Granulocytes (Neutrophils, Basophils, Eosinophils)
  • Agranulocytes (Monocytes, Lymphocytes)

  
• Fixed Macrophages


  Macrophages that stay at specific sites
• Wandering Macrophages


  Macrophages that roam the tissues and gather at sites of infection or inflammation
• Mechanism of Phagocytosis


  1. Chemotaxis

  2. Adherence

  3. Ingestion

  4. Digestion

  
• Inflammation


  A host response to tissue damage characterized by redness, pain, heat, and swelling (sometimes loss of function)
• Causes of Tissue Damage


  • Microbial infection
  • Heat, radiant energy, electricity, sharp objects (physical)
  • Acids, bases, gases (chemical)
• Functions of Inflammation


  • Destroy the injurious agent and to remove it and its by-products from the body
  • To limit the effects on the body by confining or walling off the injurious agent and its by-products (if destruction is no possible)
  • To repair or replace tissue damaged by the injurious agent or its by-products
• Process of Inflammation


  • Vasodilation and increased permeability of blood vessels
  • Phagocyte migration and phagocytosis
  • Tissue repair
• Types of Inflammation


  • Acute
  • Chronic
• Acute Inflammation


  Cause of inflammation is removed in a relatively short period of time, inflammatory response is intense
• Chronic Inflammation


  Cause of inflammation is difficult or impossible to remove, inflammatory response is longer lasting but less intense
• Vasodilation and Increased Permeability of Blood Vessels


  1. Right after tissue damage, blood vessels dilate and permeability increases

  2. Vasodilation increases blood flow to the damaged area and causes redness and heat

  3. Defensive substances retained in blood are able to pass through the walls of the blood vessels and enter the injured areas that cause edema

  4. Pain caused by inflammation may be due to nerve damage, irritation by toxins, or pressure from edema
• Chemicals Released in Response to Injury that Cause Vasodilation and Increased Permeability


  • Histamine
  • Kinins
  • Prostaglandins
  • Leukotrienes
• Fever


  Abnormally high body temperature, a systemic or overall response
• Complications of Fever


  • Rapid heart rate
  • Increased metabolic rate
  • Mild to severe dehydration
  • Electrolyte imbalances
  • Seizures in young children
  • Increased caloric demand
  • Delirium and coma
• Complement System


  A defensive system consisting of over 30 proteins produced by the liver; found circulating in blood serum and within tissues throughout the body
• Complement Pathways


  • Classical Pathway
  • Alternative Pathway
  • Lectin Pathway
• Importance of C3 Activation


  C3b enhances phagocytosis by coating a microbe (opsonization or immune adherence), C3 initiates a series of reactions that result in cytolysis
• Interferons


  Naturally occurring proteins and glycoproteins released by macrophages, lymphocytes, and tissue cells infected with a virus
• Types of Human Interferons


  • Alpha (α-IFN)
  • Beta (β-IFN)
  • Gamma (γ-IFN)
• Type I Interferons


  Alpha and Beta, produced by virus infected host cells in small quantities, help induce mRNA for antiviral protein (AVP) synthesis
• Type II Interferons


  Gamma, produced by lymphocytes, induces neutrophils and macrophages to kill bacteria by phagocytosis