Cell recognition and the immune system

• What are the specific molecules on the surface of each type of cell used for?

  To identify the cell
• Why are proteins important for cell identification?

  Because their specific 3D structure distinguishes one cell from another
• What are abnormal body cells referred to as?

  Cancer cells
• What are non-self materials?

  Cells from other organisms of the same species
• What can toxins be produced by?

  Pathogens
• What does the immune system identify using these protein molecules?

  Pathogens, non-self material, abnormal body cells, and toxins
• What is the first stage in removing pathogens?

  Identification
• Why can identification be a disadvantage for transplant patients?

  Because the immune system sees the transplant as non-self and attempts to destroy it
• How is rejection minimized in transplant patients?

  By closely matching donors to the individual and administering immunosuppressant drugs
• How many different types of lymphocytes exist before an infection?

  10 million
• What happens during clonal selection?

  It stimulates the complementary lymphocyte to divide and increase its numbers
• What explains the time lag between pathogen exposure and the body's defense response?

  The clonal selection process
• What do lymphocytes do in the fetus?

  They constantly collide with other cells
• Why don't lymphocytes in the fetus get infected?

  Because the mother protects the fetus
• What happens to lymphocytes that match the body's own cells?

  They die or are suppressed
• Where are lymphocytes produced in adults?

  In the bone marrow
• What do lymphocytes initially encounter in adults?

  Self-antigens
• What happens to lymphocytes that show an immune response to self-antigens?

  They undergo apoptosis before maturing
• What is apoptosis?

  Programmed cell death
• What is the role of lymphocytes in the immune response?

  • Identify pathogens and non-self materials
  • Respond to foreign material
  • Undergo clonal selection during infection
  • Produce antibodies to neutralize pathogens
• What are the processes involved in the immune response to a pathogen?

  1. Identification of the pathogen
  2. Clonal selection of lymphocytes
  3. Division of selected lymphocytes
  4. Attack and destruction of the pathogen
• What is the process called by which phagocytes ingest and destroy pathogens?

  Phagocytosis
• How do phagocytes prevent pathogens from causing harm?

  They ingest and destroy the pathogen through phagocytosis
• Where do some phagocytes travel?

  In the blood
• What allows phagocytes to move towards pathogens?

  Chemical products of pathogens or damaged cells act as attractants
• What do phagocytes have on their cell surface membrane?

  Many receptors that recognize and attach to chemicals on pathogens
• What is formed when phagocytes engulf a pathogen?

  A vesicle called a phagosome
• What happens to lysosomes during phagocytosis?

  Lysosomes move towards the phagosome and fuse with it
• What enzymes do lysosomes contain to destroy bacteria?

  Lysozymes
• How do lysozymes destroy ingested bacteria?

  By hydrolysis of their cell walls
• What happens to the soluble products from the breakdown of the pathogen?

  They are absorbed into the cytoplasm of the phagocyte
• What are the main steps involved in phagocytosis?

  1. Phagocytes recognize and move towards pathogens.
  2. They engulf the pathogen, forming a phagosome.
  3. Lysosomes fuse with the phagosome.
  4. Lysozymes break down the pathogen's cell wall.
  5. Soluble products are absorbed into the cytoplasm.
• What is suspended in a wet mount?

  The specimen
• Why is a wet mount said to improve image quality?

  It suspends the specimen in liquid
• What liquids are usually used in a wet mount?

  Water, oil, or glycerol
• Why can't wet mounts be stored?

  Because the water evaporates
• What are the steps to create a wet mount?

  1. Add a drop of water to the slide.
  2. Apply a thin layer of specimen in the water (one cell thick).
  3. Apply the stain (state the stain name if known).
  4. Apply a cover slip slowly using a mounted needle to avoid air bubbles.
• What is the purpose of applying a cover slip in a wet mount?

  To protect the specimen and prevent evaporation
• How should the cover slip be applied to avoid air bubbles?

  Slowly using a mounted needle
• What is a "temporary mount" in microscopy?

  A wet mount that cannot be stored