Communicable Diseases Key Words

• Pathogen

  A microorganism that causes disease
• Disease

  A condition that impairs the normal functioning of an organism
• Communicable Disease

  A disease that can spread between organisms
• Bacteria

  • Prokaryotic cells that have cell walls but lack organelles
  • Some bacteria are pathogenic, producing toxins that damage host cells
• Fungi

  • Eukaryotic, often multicellular organisms that may cause disease
  • They digest and destroy cells, and produce spores that can spread rapidly between organisms
• Tuberculosis

  • A bacterial disease that affects many parts of the body, killing cells and tissues
• Bacterial Meningitis

  • A bacterial infection in the protective membrane on the surface of the brain which can spread to the rest of the body
• Ring Rot

  • A plant bacterial disease which is a ring of decay in the vascular tissue of a potato tuber or tomato
• HIV/AIDS

  • A viral disease the gradually destroys the immune system
• Influenza

  • A virus that attacks the respiratory system
• TMV

  • A plant virus that infects tobacco plants
• Black Sigatoka

  • A fungal plant disease that causes leaf spots on banana plants
• Athletes Foot

  • A fungal disease which is a form of human ring worm
• Blight

  • A fungus-like Protoctista that affects both leaves and potato tubers
• Malaria

  • A Protoctista caused by the plasmodium parasite that spreads the disease through bites
• Direct Transmission

  When a disease is transmitted directly from one organism to another
• Indirect Transmission

  When a disease is transmitted from one organism to another via an intermediate (or vector)
• Vector

  An organism that spreads disease by carrying pathogens from one host to another
• Inflammation


  The local response to tissue damage
• Mucous membranes

  The membranes lining body cavities that secrete a sticky mucus
• Phagocytes

  • Specialised white blood cells that engulf and destroy pathogens
  • There are two types: neutrophils and macrophages
• Phagocytosis

  The process by which phagocytes engulf and destroy pathogens
• Antibodies

  Produced by B lymphocytes, bind to specific antigens that trigger the specific immune response
• Phagolysosome


  A vesicle within a phagocyte formed by the fusion of a phagosome and lysosome
• Phagosome


  The vacuole inside a phagocyte in which a foreign particle is engulfed
• Lymphocytes

  • White blood cells that contribute to the specific immune response
• Opsonins

  Chemicals that bind to and tag foreign cells, making them easily recognisable to phagocytes
• Agglutinins

  • Chemicals that cause pathogens to aggregate together, aiding phagocytosis
  • Antibodies can act as agglutinins
• Neutralisation

  Antibodies bind to the surface of the pathogen to make them harmless
• Anti-toxins

  Chemicals produced by white blood cells that neutralise toxins release by pathogens
• Antigen

  A chemical present on the surface of a cell that induces an immune response
• Antigen-presenting cell

  A macrophage that displays foreign antigens
• B effector cells

  • A type of B lymphocyte that divides to form plasma cells
• B lymphocytes

  • Lymphocytes that mature in the bone marrow
  • There are three main types; plasma cells, B effector cells and B memory cells
• B memory cells

  • B lymphocytes that provide immunological memory
• Plasma cells

  • B lymphocytes that produce antibodies specific to a particular antigen
• Primary Response

  The immune response when a pathogen first enters the body
• Interleukins

  Cytokines produced by T helper cells that stimulate B cells
• Secondary Response

  The immune response if the same pathogen invades again
• T helper cells

  • T lymphocytes with CD4 receptors on the cell surface membrane
  • These bind to antigens on antigen-presenting cells and secrete interleukins