Infection and Response

• Pathogen - A microorganism that causes infectious disease
• Communicable - A disease that can be transmitted from one organism to another
• Infectious - Describes a pathogen that can easily be transmitted, or an infected person who can pass on the disease
• Vector - An organism that spreads a communicable disease e.g. Mosquito
• Toxins - A poison that damages tissues and makes us feel ill
• Malaria - A communicable disease, caused by a protest carried in mosquitoes, which attacks red blood cells
• Insecticide - A chemical that kills insects
• Cilia (ciliated epithelial) - Tiny hair-like projections from epithelial cells that waft mucus out of the gas exchange system
• Mucus - A sticky substance that traps pathogens
• Trachea - The tube through which air travels from the mouth and nose to the lungs. Also known as the windpipe
• Bronchi - The airways that lead from the trachea into the lungs
• Antibiotics - A drug that helps to cure bacterial disease by killing infective bacteria inside the body
• Antigen - A protein on the surface of a pathogen that antibodies can recognise as foreign
• The immune system - The organs and processes of the body that provide defence against infection and toxins
• Antibodies - A special protein that is a complementary match to a specific antigen (produced by white blood cells)
• Phagocytes - A type of white blood cell that engulfs and destroys pathogens
• Phagocytosis - The process where a pathogen is engulfed and destroyed by white blood cells
• Antitoxins - A chemical produced by white blood cells that neutralises a toxin
• Lymphocyte - A type of white blood cell that produces antibodies
• A drug - is a chemical used to alter someone's physical or mental state.
• Placebo - a substance that looks like the drug but that does not contain the active ingredients, so it has no effect on the body. For example, it could be a sugar tablet or vitamin tablet.
• Lymphocytes - ( a type of white blood cell ) can produce antitoxins which have a complementary shape to the toxins released by bacteria. The antitoxins bind to the toxins and neutralise them.
• How do you use mould to make medicine?

  1. Penicillin mould produces penicillin antibiotic.

  2) Scientists grow the mould in fermenter tanks.

  3) Scientists separate the penicillin antibiotic from the mould.

  4) Penicillin is purified and used as an antibiotic medicine.
• What makes a good drug?

  1. Effective - must cure or prevent a disease, or at least make you feel better.

  2) Safe - must not be toxic, or have unwanted side effects.

  3) Successfully taken in and removed from your body.

  4) Only affects the body where it is supposed to.
• Why placebos and double-blind trials are important for testings whether a drug is effective or not?

  Placebos and double blind trials are important for testing whether a drug is effective or not because comparing the results from both groups should show the effects of the medication.
• What do the eyes produce that contains a natural antiseptic?

  Tears
• How do hair and mucus in the nose contribute to the body's defenses?

  They trap particles that could contain pathogens, preventing them from entering the airway.
• What substance does the stomach produce to kill pathogens?

  Hydrochloric acid
• What role do blood platelets play in the body's defenses?

  They seal open cuts and wounds.
• How does mucus and ciliated cells in the trachea and bronchi protect the body?

  Mucus traps pathogens, which are then wafted back up the throat by ciliated cells to be swallowed.
• What is the function of the skin in the body's defenses?

  It forms a barrier to pathogens and secretes antimicrobial substances.
• What are the main components of the body's defenses mentioned in the study material?

  • Tears containing natural antiseptic
  • Hair and mucus in the nose trapping particles
  • Hydrochloric acid in the stomach
  • Blood platelets sealing cuts and wounds
  • Mucus and ciliated cells in the trachea and bronchi
  • Skin forming a barrier and secreting antimicrobial substances
• How are pathogen spread?

  -direct contact

  -in air

  -animal vectors

  -break in skin

  -contaminated food

  -contaminated water
• Area of a circle: A=TTr² 
• percentage change = (New Price - Old Price) ÷ Old Price, and then multiply that number by 100
• Clinical trials

  To make it a fair test, healthy volunteers or patient volunteers at each stage of the clinical trial are separated into 2 groups: test and control
• Phagocytosis

  1. Pathogenic bacteria enter our body and releases toxins which makes us feel ill.

  2) A phagocyte (a type of white blood cell) recognises a bacterium and moves towards it.

  3) The phagocyte engulfs the bacteria.

  4)The phagocyte's enzymes digest the bacterium, which kills it.

  5) The digested materials are absorbed or released out of the phagocyte, which can go on to destroy another bacterium.
• Investigating the effectiveness of antiseptics

  It is important that your experiment is not contaminated with unwanted microorganisms. precautions you take to stop this are: only lift the lid slightly and clean the surface. You put water on one of the discs, so you can compare the difference between clear zone areas. Seal the plate with only 2 small pieces of tape because you don't want anaerobic bacteria to grow on it. You can tell which antiseptic was the most effective by looking at the one which has the bigger clear zone around it.
• Vaccination

  A dead/weakened pathogen is injected into an individual's bloodstream. While blood cells produce specific antibodies against the dead/weakened pathogen. Antibodies bind to the dead/weakened pathogen and kill it. The vaccinated individual encounters the same pathogen again. Memory cells in the blood immediately recognise the pathogen and make a higher concentration of specific antibodies quickly. Antibodies bind to the pathogen and kill it.
• Having more vaccinated people in the population prevents the spread of pathogen in a population because you may come across someone who has been infected. Also you are surrounded by vaccinated people.