11.1 BODY DEFENSE

• What symptoms indicate that the immune system is working to help the body recover from an infection?


  Fever, headache, or rash
• How does the immune system recognize pathogens?


  Pathogens are recognized as foreign antigens by the immune system
• What triggers an immune response in the body?


  The activation of the immune system by a pathogen trying to infect body cells
• What are antibodies and what is their role in the immune response?


  Antibodies are proteins produced by lymphocytes to destroy antigens
• What does it mean for the body to have developed immunity towards a disease?


  It means the body can resist a particular disease or infection
• What is the immune system composed of?


  • Cells
  • Tissues
  • Organs
• What are pathogens?


  Pathogens are disease-causing microorganisms
• What is an immune response?


  An immune response is a biological reaction to destroy pathogens
• What is an antigen?


  An antigen is a molecule on the surface of a pathogen that stimulates an immune response
• What is an antibody also known as?


  Immunoglobulin (Ig)
• What type of cells are lymphocytes?


  Lymphocytes are a type of white blood cell
• What are the three lines of body defense against diseases?

  The first line, second line, and third line of defense
• What does the first line of defense consist of?

  • Physical barriers (skin)
  • Chemical barriers (saliva, tears, stomach acid)
  • Non-specific defense against all pathogens
• What is the role of skin in the first line of defense?


  Skin prevents microorganisms from entering the body
• How does the skin act as a chemical barrier?

  By secreting sebum that inhibits the growth of microbes
• What does stomach acid do in the first line of defense?


  It helps destroy bacteria in food and drinks
• What is the pH range of stomach acid?


  The pH of stomach acid is as low as 1.5 to 3.5
• What is the function of the blood clotting mechanism?


  To prevent microbes from entering through open wounds
• What is mucus and where is it found?


  Mucus is a sticky substance produced by mucous membranes
• How does mucus protect the respiratory system?


  Mucus traps irritants like dust and bacteria from entering the respiratory system
• What is lysozyme and where is it found?


  Lysozyme is an antimicrobial enzyme found in tears, saliva, and mucus
• What happens during the second line of defense?


  It protects the body when pathogens breach the first line of defense
• What are examples of the second line of defense?


  Fever, phagocytosis, and inflammatory response
• How does fever help the body during an infection?


  It increases body temperature to facilitate phagocytic activity
• What is phagocytosis?


  Phagocytosis is the process of engulfing large particles like microorganisms
• What types of cells carry out phagocytosis?

  Phagocytes, such as neutrophils, monocytes, and macrophages
• What are the steps of phagocytosis?


  1. Phagocyte extends pseudopodia to engulf the pathogen
  2. Ingestion forms a phagosome
  3. Lysosome fuses with phagosome to form phagolysosome
  4. Lysozyme breaks down the pathogen
  5. Remains of the dead pathogen are excreted
• What is inflammation?

  Inflammation is the body's immediate response to remove irritants like pathogens
• What are the five cardinal signs of inflammation?


  Pain, swelling, redness, heat, and loss of function
• What is pus a result of?


  Pus is a natural result of the body's inflammatory response
• What happens during the inflammatory response?


  1. Injury allows pathogens to enter
  2. Histamine is released, triggering inflammation
  3. Increased blood flow brings platelets and phagocytes
  4. Phagocytes carry out phagocytosis
  5. Blood clotting begins
• What activates the third line of defense?


  The third line of defense is activated when the second line is breached
• What is the third line of defense also known as?


  The immune response
• What type of response does the third line of defense provide?


  A specific adaptive response targeting specific pathogens
• What cells are primarily involved in the third line of defense?

  Lymphocytes
• How do lymphocytes respond to antigens?


  Lymphocytes produce specific antibodies in response to specific antigens
• What practice questions are included in the study material?

  • 11.1 - Body Defence
  • 11.2 - Actions of Antibodies
  • 11.3 - Types of Immunity
  • 11.4 - Health Issues Related to Immunity