blood and bodily defenses

• What is the body's first line of defense against infection?

  Stops pathogens from entering the body
• How does the skin act as a barrier against pathogens?

  It is a physical barrier difficult to penetrate
• What role do sweat glands play in defending against pathogens?

  They produce oils that kill microorganisms
• What does the acid in the stomach do?

  Kills pathogens in contaminated food
• How do cilia and mucus in the airways protect the body?

  Mucus traps microorganisms, cilia move it up
• What is the function of nasal hairs?

  Keep out dust and larger microorganisms
• What do tears contain that helps destroy bacteria?

  Lysozymes
• What are ciliated cells and their function?

  They waft mucus and pathogens upwards
• What do goblet cells do?

  They create mucus to catch pathogens
• How does mucus in the airways serve as a barrier?

  It physically traps pathogens
• What happens if the skin is damaged?

  Pathogens could enter the body
• How is damaged skin repaired?

  Through the formation of a scab
• What occurs when the skin is cut and starts to bleed?

  Blood leaks out of the body
• What do platelets do when the skin is cut?

  Change fibrinogen into fibrin
• What forms a blood clot?

  Red blood cells trapped in fibrin fibers
• What happens to the clot after it forms?

  It hardens to form a scab
• What is the purpose of a scab?

  Keeps the skin clean and aids healing
• What happens to the scab over time?

  It will eventually fall off
• What are phagocytes?

  White blood cells that attack pathogens
• How are phagocytes attracted to pathogens?

  By chemicals released by pathogens or damaged cells
• What happens when a phagocyte attaches to a pathogen?

  The phagocyte engulfs the pathogen
• What role do enzymes play in phagocytes?

  They break down and destroy pathogens
• Why are phagocytes considered non-specific?

  They attack all pathogens they encounter
• What are lymphocytes?

  Another type of white blood cell
• What do lymphocytes recognize on pathogens?

  Proteins called antigens
• What do lymphocytes produce in response to antigens?

  Y-shaped antibodies
• What happens during the few days it takes for lymphocytes to produce antibodies?

  The person may feel ill
• What do antibodies do once released into the bloodstream?

  They bind to pathogens and restrict movement
• How do antibodies assist phagocytes?

  By making it easier for phagocytes to engulf pathogens
• What happens once a person has produced a specific antibody?

  They are usually immune to the pathogen
• What do some pathogens produce that makes you feel ill?

  Toxins
• What do lymphocytes produce to neutralize toxins?

  Antitoxins
• How do antitoxins protect body cells?

  By preventing toxins from binding to them
• Why are antibodies and antitoxins considered specific?

  They are specific to the antigen or toxin
• What type of lymphocytes produce antibodies?

  Specific lymphocytes