Cell recognition and the Immune system

• Defence mechanisms


  Processes and structures that protect the body from pathogens
• Non-specific


  First-line and second-line of defence mechanisms that are immediate and the same for all pathogens
• First-line of defence


  Physical and chemical barriers that prevent pathogen entry (e.g., skin, mucous membranes)
• Second line of defence

  Non-specific response mechanisms (e.g., phagocytic white blood cells, antimicrobial proteins)
• Specific


  Third line of defence mechanisms that are slower and specific to each pathogen
• Third line of Defence

  Immune response involving lymphocytes, antibodies, and specific recognition of pathogens
• Skin


  Protective covering that acts as a physical barrier against pathogen entry
• Phagocytic white blood cells


  Cells that engulf and destroy pathogens
• Mucous membranes


  Epithelial cells covered in mucus that provide a further defence against invasion
• Lymphocytes


  White blood cells that recognize and respond to foreign molecules
• Antibodies


  Proteins produced by lymphocytes that neutralize pathogens
• Secretions of Skin and mucous membranes


  Substances that have antimicrobial properties and help protect against pathogens
• Inflammatory response


  Non-specific response that involves redness, swelling, heat, and pain
• Immunity


  The ability of the immune system to distinguish between self and non-self molecules
• Self molecules


  Components of an organism's body that can be distinguished from foreign substances by the immune system
• Non-self molecules


  Foreign molecules recognized by the immune system
• Antigens


  Toxins or foreign substances that induce an immune response in the body
• Body's barriers to entry

  Physical and chemical barriers that prevent pathogen entry into the body
• Protective covering


  The skin, which covers the body surface and provides a physical barrier against pathogen entry
• Mucus


  Substance produced by many epithelial cells that acts as a defence against invasion
• Hydrochloric acid in the stomach


  Acid that provides a low pH environment in the stomach, killing most pathogens
• Cell-mediated responses


  Immune responses involving T lymphocytes
• Humoral responses

  Immune responses involving B lymphocytes
• Self or non-self cells

  Cells that have specific molecules on their surface to identify them as self or non-self
• Organ transplant


  Transfer of cells, tissues, or organs from one individual to another
• Tissue rejection


  Immune response against cells from an organ transplant perceived as non-self
• Immunosuppressant drugs


  Medications that reduce the immune response to minimize tissue rejection
• B-cell receptors


  Proteins on the surface of B cells that recognize specific antigens
• Apoptosis

  Programmed cell death
• Infection


  Interaction between a pathogen and the body's defence mechanisms
• Immunity


  Body's ability to defend against a second infection from the same pathogen
• Variety of specific 3-D structure


  Distinguishing feature of cells that allows the immune system to recognize them
• Random assembly of genes


  Process by which B-cell receptors are generated with different specificities
• Mutation


  Change in DNA that leads to a slightly different protein and B-cell receptor
• Tissue rejection


  Immune response against cells from an organ transplant perceived as non-self
• B-cells targeting own cells


  Potential problem where B-cells are programmed to attack the body's own cells
• Self Cells


  The body's own cells and molecules
• Non-Self Cells


  Foreign cells and molecules invading someone
• Non Specific Defense

  A bodily response that is immediate and applies to all pathogens entering the body
• Specific Defense

  A slower bodily response that is specific based on each pathogen entering the body