6.62 Immune system

• What is the immune system responsible for?

  Protecting the body from pathogens
• Why is the immune system considered fascinating?

  It works continuously to protect against pathogens
• What are examples of pathogens?

  Viruses, bacteria, fungi, protists
• What is the first line of defense against pathogens?

  Skin and mucous membranes
• Why is the first line of defense considered nonspecific?

  It blocks all pathogens indiscriminately
• What is the second line of defense in the immune system?

  The inflammatory response
• What happens when you step on a sharp stick?

  Mast cells release histamine causing inflammation
• What substance do mast cells release during an inflammatory response?

  Histamine
• What effect does histamine have on blood vessels?

  It causes them to dilate and leak
• What role do macrophages play in the immune response?

  They consume pathogens
• What is the complement system's function?

  It helps enhance immune responses
• What is the third line of defense in the immune system?

  The specific immune response
• What is adaptive immunity?

  A specific response to an antigen
• What is an antigen?

  A substance recognized as non-self
• What is the role of cytotoxic T cells?

  To destroy infected cells
• How do cytotoxic T cells induce apoptosis?

  By releasing perforin to damage cell membranes
• How are cytotoxic T cells stimulated?


  By infected cells presenting antigens
• What do T-helper cells do?

  They stimulate other immune cells
• What is the humoral response?

  A response involving B cells and antibodies
• What do B cells produce?

  Antibodies
• What is the structure of antibodies?

  They are Y-shaped proteins
• How do antibodies deactivate pathogens?

  By affecting their movement and reproduction
• What are memory cells in the immune system?

  Cells that remember past antigens
• What is the role of vaccines?

  To introduce weakened pathogens for immunity
• Why is memory in the immune system important?

  It allows for a faster response to pathogens
• What are the three lines of defense in the immune system?

  1. First line: Skin and mucous membranes (nonspecific)
  2. Second line: Inflammatory response (nonspecific)
  3. Third line: Adaptive immunity (specific)
• What are the two types of adaptive immune responses?

  1. Cell-mediated response

  • Involves cytotoxic T cells
  • Destroys infected cells

  1. Humoral response

  • Involves B cells
  • Produces antibodies
• What are the differences between antigens, antibodies, and antibiotics?

  • Antigens: Recognized as foreign by the immune system
  • Antibodies: Proteins that bind to specific antigens
  • Antibiotics: Substances that destroy bacteria
• Why do larger organisms need a transport system?

  They cannot rely on diffusion alone
• What are the three important components of the human circulatory system?

  Blood, heart, and blood vessels
• What happens to blood when spun in a centrifuge?

  It separates into distinct layers
• What is the top layer of separated blood called?

  Plasma
• What is the primary function of red blood cells?

  To carry oxygen around the body
• Where are red blood cells made?

  In the bone marrow
• How many red blood cells are in a cubic millimeter of blood?

  Approximately 5 million
• What shape do red blood cells have?

  Biconcave shape
• Why do red blood cells lack a nucleus?

  To pack more hemoglobin
• What is hemoglobin's role in red blood cells?

  To carry oxygen
• What is formed when hemoglobin picks up oxygen?

  Oxyhemoglobin
• What is the primary function of white blood cells?

  To protect against pathogens