Key Terminology

• Pathogen

  Substances that cause diseases, virus, bacteria, protist, or fungi
• Skin & Mucous Membrane

  Your first line of defense, a physical barrier. Non specific. protects you from letting a substance get inside of you. Mucus lined air passages which trap pathogens.
• Inflammation


  A reaction to injury or infection. Second line of defense, Swelling and fever. Make your blood vessel more permeable to blood and white blood cells.
• Antimicrobial proteins


  These proteins can be secreted onto the surface of the skin or the actual soft tissue. Prevent and kill bacterial growth.
• Histamine


  An important substance that call the immune system to your skin and make sure nothing is moving into the bloodstream. Histamine attracts phagocytes.
• Phagocytes Destroy any pathogens, either the actual cell or bits and pieces of the remains .
• Helper T (CD4)


  Specific Immunity, Third line of defense, Alert the body that you have been infected.
• Killer T

  Destroy viruses and cancer cells. Specifically target host cells
• B lymphocytes are the most abundant lymphocytes in the blood and are responsible for antibody production
• Plasma cell


  Produced by B-lymphocytes, which produce antibodies
• Antibodies

  Match up with a specific Pathogen, and that pathogens Antigen will tell us whether they belong or not. And then respond to the pathogen cell.
• Memory cells


  They will remember the infection, so next time if we are exposed. The immune response is faster.
• Lymphocyte - white blood cell type which fight infection
• Antigen - a complex molecule that induces an immune response (or disease reaction) in the body
• Antibody - a protein made by the immune system to target and combine with a specific antigen (invader) and make it useless
• Phagocytosis - the process by which a cell engulfs a solid particle to form an internal compartment known as a phagosome (phago - eat, cyto-cell)
• Lysosome - an organelle containing digestive enzymes to break down bacterial or viral cell walls
• Vaccine - a biological preparation made from damaged virus or bacteria particles used to stimulate an immune response by the body's immune system against viral and bacterial infectious diseases
• Antibiotic - medicine e.g. penicillin which is developed from living organisms e.g. bacteria or fungi and used to fight infections caused by either bacteria or fungi
• Insulin - hormone made in the pancreas and released into the blood to help convert glucose to glycogen
• Pathogen - Infectious biological agent or organism that causes disease An agent who carries and transmits an infectious pathogen into another living organism.
• Vector - an agent who carries and transmits an infectious pathogen into another organism
• Host - Living cell in which a virus (or foreign molecule or microorganism) multiplies or hides.
• Epidemic - Refers to a sudden increase in the number of cases of a disease above what is normally expected.
• Pandemic - Refers to an epidemic that has spread over several countries or continents, usually affecting a large number of people
• Rabies affects both domestic and wild animals such as dogs . The rabies virus is passed from one animal to another in saliva. Humans usually get infected when they are bitten by a rabid animal.
• Acquired Immune Deficiency Syndrome (AIDS) is a sexually transmitted disease caused by the Human Immunodeficiency Virus (HIV)The virus weakens the immune system by infecting and destroying the immune cells which are known as the CD4 – cells.
• Influenza is commonly called “flu” and is caused by the influenza virus. The virus spreads through the air when a patient coughs or sneezes
• Viruses do not respond to antibiotics. Flu is best managed with the use of vaccines.
• Cholera is commonly found in areas where there is overcrowding, unsafe drinking water and a lack of proper sanitation Cholera is caused by the bacterium Vibrio cholerae
• The bacterium, Mycobacterium tuberculosis causes the lung disease tuberculosis (TB. The bacterium can also attack other parts of the body such as the kidneys, brain and spinal cord.

  TB is spread through the air when infected people cough or sneeze. The bacterium spreads quickly in confined, overcrowded spaces where there is poverty and poor sanitation.
• Diseases caused by viruses: Rabies, measles, mumps, chicken pox, influenza, HIV/AIDS
• Diseases caused by bacteria: cholera, tuberculosis, gonorrhoea
• Diseases caused by Protista: Malaria -- Leishmaniasis, Toxoplasmosis
• Malaria is a life-threatening disease found mainly in tropical and sub-tropical areas of the world.

  • Malaria is caused by the protozoan Plasmodium vivax and is spread by the female Anopheles mosquito.

  • The female Anopheles mosquito is called the vector.

  • A vector carries a disease-causing organism from an infected host to a new host.
• Diseases caused by fungi: Thrush, ringworm, athlete's foot
• Thrush is caused by a yeast (fungus) called Candia albicans.
• Athlete’s foot is a fungal infection found mainly between the toes and on the arches of feet . It is caused by the fungus Tinea pedis. The fungus feeds on the keratin (protein) in the skin and results in flaky and cracked skin. The cracks allow bacteria to enter.

  This fungus thrives in warm, moist places. It may be contracted by walking barefoot in public places such as showers, public swimming pool areas and changing rooms
• The first line of defense in plants includes the waxy cuticle, bark and the closely packed epidermal cells which protects them from invading micro-organisms. If a plant is injured, it can produce sticky gums and resins in an attempt to seal the wound and prevent infection.
• The second line of defense occurs when a plant becomes infected by a pathogen and its natural immune response is activated. It releases chemical compounds such as salicylic acid which are transported in the phloem to cells which are not affected. The unaffected cells respond by producing various chemical defenses to protect themselves.