Infection + Response

• What are pathogens?

  Pathogens are microorganisms that enter the body and cause disease, they cause communicable diseases.
• What are the 4 types of pathogens?

  Virus, bacteria, fungi and protist
• bacteria:

  can reproduce rapidly inside the body, they make you ill by producing toxins which damage your cells and tissues.
• Viruses:

  Are not cells, they can reproduce rapidly inside the body, they live inside your cells and replicate themselves by producing copies of themselves, the cell will eventually burst, releasing all new viruses. Cell damage is what makes you feel ill.
• Protists:

  They’re eukaryotes and most of them are single celled, some protists are parasites. Parasites live on or inside other organisms and cause them damage, are often transferred to an organism by a vector (an insect that carries a protist)
• Fungi:

  Some are single celled , others have a body which is made up of hyphae (thread like structures). Hyphae can grow and penetrate human skin and surface of plants causing diseases. The hyphae can produce spores which can spread to other animals or plants
• How can pathogens be spread?

  Through water - drinking or bathing in dirty water

  Air - airborne pathogens carried in the air in droplets

  Direct contact - touching contaminated surfaces
• Examples of viral disease:

  Measles, HIV and Tobacco Mosaic Virus (TMV)
• Examples of fungal diseases:

  Rose black spot
• Example of protist disease:

  Malaria
• Examples of bacterial disease:

  Salmonella and Gonorrhea
• How to reduce/prevent the spread of disease:

  Being hygienic, destroying vectors, isolating infected individuals and vaccinations
• What’s the body’s defence system?

  The skin acts as a barrier to pathogens, it secretes antimicrobial substances which kill pathogens.

  Hair and mucus in your nose trap particles that contain pathogens.

  The trachea and bronchi secrete mucus to trap pathogens, also are lined with cilia which waft the mucus up to the back of the throat to be swallowed.

  The stomach produces hydrochloric acid which kills pathogens that make it far from the mouth.
• What’s the process of phagocytosis?

  The white blood cells engulf foreign cells and digest them.
• Producing antibodies:

  Every invading pathogen has unique molecules (called antigens) on its surface. When some types of white blood cells come across a foreign antigen they will produce proteins called antibodies to lock onto the invading cells so that they can be found and destroyed. The antibodies produced are specific to that type of antigen - they won’t lock onto any others. Antibodies are produced rapidly and carried around the body to find a similar bacteria or virus. If the person is infected with the same pathogen again, the white blood cells will rapidly produce antibodies to kill it - the person is naturally immune to that pathogen.
• What are the three processes to fight disease?

  -phagocytosis

  -producing antibodies

  -producing antitoxins
• Producing antitoxins:

  These counteract toxins produced by the invading bacteria
• What are vaccinations?

  Vaccinations involve injecting small amounts of dead or inactive pathogens. These carry antigens, which causes your body to produce antibodies to attack them - even though the pathogen is harmless. So if the pathogens of the same time appear after that, the white blood cells can rapidly produce antibodies to kill the pathogen.
• What are the advantages of vaccinations?

  Have helped control lots of communicable diseases that were one common. Epidemics can be prevented if a large percentage of the population is vaccinated - fewer people likely to get the disease
• What are the disadvantages of vaccinations?

  Vaccines don’t always work, sometimes don’t give you immunity.

  There can be a bad reaction to the vaccine, however it’s rare.
• How do painkillers work?

  Painkillers are drugs that relieve pain, however they don’t tackle the cause of the disease or kill pathogens, they just help reduce the symptoms
• How do antibiotics work?

  Antibiotics kill/prevent the growth of bacteria causing the problem without killing your own body cells.
• Why can’t antibiotics destroy viruses?

  Viruses reproduce using your body cells so it’s difficult to develop drugs that destroy the virus, without killing the body’s cells
• How can bacteria become resistant to antibiotics?

  Bacteria can mutate which can cause them to be resistant to an antibiotic. If you have an infection, some of the bacteria might be resistant to antibiotic, this means when you treat the infection only non-resistant strains of bacteria can be killed. The individual resistant bacteria will survive and reproduce and the population of the resistant strain will increase. The resistant strain may cause a serious infection that can’t be treated by antibiotics.
• How can you reduce the rate of resistant strains?

  To slow down the rate of development of resistant strains, it’s important for doctors to avoid over prescribe antibiotic. It‘s also important to finish the whole course of antibiotics - not just stop once you feel better.
• Where did many drugs originally come fro?

  From plants, plants produce a variety of chemicals to defend them against pests and pathogens. Some of these chemicals can be used as drugs to treat human diseases or relieve symptoms. E.g. aspirin - developed from a chemical found in willow
• How are some drugs made?

  They can be extracted from microorganisms, e.g. Flemming produced penicillin to kill bacteria in a petri dish.

  Or made large scale in the pharmaceutical industry - synthesised by chemists in labs
• What are the stages of drug testing?

  1.Preclinical testing - drugs are tested on human tissues and cells in a lab.

  2.Test the drug on live animals, to test efficacy and to find its toxicity and to find the best dosage.

  3.Tested on human volunteers in a clinical trial, it‘s tested on healthy volunteers to make sure there’s no harmful side effects, at the start of the trial a low dosage is given then it gradually increases. It is then tested on people who have the illness to find the optimum dose. Then to see how well it work, patients are placed in two groups one is given the drug the other is given the placebo - to see the actual effect of the drug, it’s a double blind trial the patient nor doctor knows the results until the results have been gathered. The results aren’t published until they’ve been through peer review; to prevent false claims.
• What are the reasons for drug testing?

  To find the dosage, toxicity and efficacy (if the drug works)