LS1- Immunity and immune response

• The major components of immune system are:

  • Bone marrow
  • Lymphoid tissue
  • Lymphatic system
• WBCs that are involved in immunity are produced in the bone marrow
• B cells mature in the bone marrow
• T cells move from bone marrow to thymus to mature
• Lymphoid tissue

  • the spleen acts like a filter.
  • Red pulp: destroys old and injured RBC's
  • White pulp: has concentrations of lymphocytes
• Lymphatic system remove foreign material from lymph system before it reaches the blood stream
• Functions of the immune system

  • to remove foreign antigens like viruses and bacteria to maintain homeostasis
• 2 general types of immunity are: natural and acquired
• Natural immunity

  • 1st line defense
  • protects the host without memory
  • responds to pathogens by making cytokines
  • acts to control and eliminate pathogens through production of cytokines
• Acquired immunity

  • develops after birth
  • 2nd line of defense
  • "immune memory" from prior exposure
  • active defenses developed by self from previous infection or immunization lasting for years or life
  • passive defenses are from temporary transfer from external source. For example, mom to baby in utero; breast feeding; injection
  • They defend and destroy to protect afainst re exposure or active illness
• Antigen is a substance that the body recognizes as foreign, triggering an immune response. When antigens are introduced into the body, antibodies are produced in response
• Antibodies

  • neutralizes antigens by binding to their surface and blocking their activity
  • facilitate phagocytosis by marking antigens surface and allowing the body cells to recognize, engulf, and destroy them
  • activate complement system to lyse foreign substances and enhance phagocytosis
• What are the 4 defense mechanism of NATURAL IMMUNE SYSTEM?

  • WBC
  • inflammatory response
  • physical and chemical barriers
  • immune regulation
• WBC

  • granulocytes fight invasion by releasing cell mediators and engulf toxins
  • neutrophils are first to arrive in inflammation
  • monocytes engulf, ingest, and destroy toxins
• Inflammatory response

  • major function that is elicited in response to injury
  • chemical mediators assist this response by minimizing blood loss, activate phagocytes, and promote scar tissue formation
• Physical and chemical barriers

  • Physical: filter and clear skin, mucus membranes, cilia, cough, sneeze
  • chemical: remove or destroy mucus, gastric acid, enzymes in tears/saliva sweat
• Immune regulation

  • balances system to ensure response is strong enough to kill, but not destroy itself
• 3 main defense mechanism of acquired immunity

  • phagocytosis
  • humoral response
  • cellular response
• phagocytosis

  • ingest foreign particles and destroy invading agent
  • remove bodys own dying or dead cells
  • aptosis is the body's way of destroying worn out cells that needs to be removed
• humoral reponse

  • "antibody response"
  • begins with B lymphocytes -> transform themselves to plasma cells that make antibodies which are transformed in the blood stream and attempt to disable invaders
• cellular response

  • involves T cells which turns to cytotoxic T cells that can attack pathogens
• Stages of Immune response

  1. recognition stage, antigens are recognized by circulating lymphocytes and macrophages.
  2. proliferation stage, the dormant lymphocytes proliferate and differentiate into cytotoxic (killer) T cells or B cells responsible for formation and release of antibodies. 
  3. response stage, the cytotoxic T cells and theB cells perform cellular and humoral functions, respectively
  4. effector stage, antigens are destroyed or neutralized through the action of antibodies, complement, macrophages, and cytotoxic T cells.