Chapter 5

• What does your health refer to?

  Your health is a state of mental and physical wellbeing
• What is the definition of a communicable disease?


  Communicable diseases are caused by pathogens and can be passed from one person to another.
• What is the definition of a non-communicable disease?


  A non-communicable disease can't be passed from one person to another
• What factors can affect your health?

  Diet, stress and life situations can all affect your health
• What are pathogens?


  Pathogens are microorganisms that cause infectious diseases. They consist of bacteria, viruses, protists and fungi.
• What are the differences between bacteria and viruses?

  -Bacteria are single cells that can survive on their own, inside or outside the body.

  -They divide by binary fission.

  -They produce toxins that damage our cells and can be treated with antibiotics.

  -They are transmitted by air and contaminated food or water.

  
  

  -Viruses cause infections by entering and multiplying inside the host's healthy cells

  -They are much smaller than bacteria.

  -Viruses destroy cells

  -They can be treated with vaccines

  -They are transmitted by air and direct contact
• How do pathogens spread?


  -Pathogens can be spread by air in tiny droplets that we expel when we cough or sneeze

  -Pathogens can be spread by contaminated food or water so they enter through your digestive system

  -Pathogens can be spread by touching contaminated surfaces
• Define binary fission


  Bacteria reproduction by mitosis
• What is a culture medium?


  a liquid/gel with specific nutrients to support microorganisms growth
• What is agar gel?


  A solid gel culture medium used for growing microorganisms
• How can uncontaminated cultures of microorganisms be used ?

  To investigate effects of disinfectants and antibiotics
• Why can't the Petri dish be sealed when growing microorganisms?


  To allow oxygen in, preventing harmful anaerobic bacteria from growing
• Why must we not incubate cultures above 25C in schools?


  To prevent harmful bacteria growth
• How long does it take for bacteria to multiply in the right conditions?

  20 minutes
• Give a step by step description of growing microorganisms in a lab

  -The nutrient agar is sterilised to kill of any bacteria

  -Hot agar gel is poured into a sterile Petri dish and then left to cool.

  -Glass dishes are sterilised by being heated in an autoclave

  -sterilise the inoculating loop by passing it through a Bunsen burner

  -Dip the loop into the bacteria and make zigzag streaks across the surface of the agar

  -Do this by a Bunsen and only take the lid off for a short period of time to avoid contamination from the air

  -Fix the lid in place with adhesive tape to prevent microorganisms from the air contaminating it but don't seal all the way around it as some oxygen is needed for the growth of the bacteria

  -The petri dish should then be labelled and stored upside down to stop condensation falling onto the agar surface
• What are disinfectants?


  Chemicals used to kill bacteria in the environment around us
• What are antiseptics?


  Disinfectants that are safe to use on human skin
• What are antibiotics?


  Chemicals used to kill bacteria inside the human body
• How can you investigate the effects of different disinfectants and antibiotics?


  You can add circles of filter paper soaked in different types and concentrations of disinfectants and antibiotics when you set up your culture plate. An area of clear gel indicates that the bacteria have been killed or can't grow, it is called the zone of inhibition
• How can the spread of disease be reduced or prevented?


  -Simple hygiene measures

  -destroying or controlling vectors

  -vaccination

  -isolating infected individuals
• What did Ignaz Semmelweis do?


  Showed that handwashing decreased the incidence of puerperal fever
• What did Louis Pasteur do?


  He showed that microorganisms caused disease. He developed vaccines against some diseases
• What did Joseph Lister do?


  He used a chemical disinfectant to prevent surgical wound infections
• Why did other doctors resist Semmelweis's theory?


  The inability to see microorganisms made it difficult to understand how diseases spread
• What are some examples of viral diseases?

  measles, HIV, tobacco mosaic virus
• Describe measles


  Measles is a viral disease. It is spread through droplets from an infected person's sneeze or cough. It causes people to develop a red skin rash and they'll show signs of a fever

  Measles can sometimes lead to pneumonia, encephalitis (a brain infection) and can even be fatal. Most people are vaccinated against measles
• Describe HIV


  HIV is a virus spread by the exchange of bodily fluids or sexual contact. HIV can initially cause flu-like symptoms, put then show no symptoms for several years. HIV can be controlled with antiretroviral drugs which stop the virus replicating in the body. If the body's immune system is badly damaged, it can't cope with other infections or cancers, this is known as AIDs
• Describe rose black spot

  Rose black spot is a fungus that causes purple or black spots to develop on the leaves of rose plants. The leaves can turn yellow and drop off. This means less photosynthesis can happen, so the plant doesn't grow very well . It spreads through the environment in water or by the wind. The disease can be treated using fungicides and by stripping the plant of its affected leaves. These leaves need to be destroyed so that the fungus doesn't spread
• Describe Malaria


  Malaria is caused by a protist. The mosquitos are vectors-they pick up the malarial protist when they feed on an infected animal. Every time the mosquito feeds on another animal, it infects it by inserting the protist into the animal's blood vessels. Malaria causes repeating episodes of fever and can be fatal. The spread of malaria can be reduced by stopping the mosquitos from breeding and making sure people can be protected from bites.
• Describe Tobacco Mosaic Virus


  Tobacco mosaic virus is a virus that causes a mosaic pattern on the leaves of a plant-parts of the leaves become discoloured. This means that the plant can't carry out photosynthesis, so the virus affects the growth of the plant
• Describe samonella


  Salmonella is a type of bacteria that causes food poisoning. You can get it by eating food that's been contaminated with salmonella bacteria. Infected people can suffer from fever, stomach cramps, vomiting and diarrhoea. These symptoms are caused by the toxins that the bacteria produce. In the UK, most poultry are given a vaccination which controls the spread of the disease and stops it from being passed on to humans
• Describe Gonorrhoea


  Gonorrhoea is a sexually transmitted disease (STD) caused by bacteria. A person with gonorrhoea will get pain when they urinate and will have a thick yellow or green discharge. To prevent the spread of gonorrhoea, people can be treated with other antibiotics and should use barrier methods of contraception.
• What is Agrobacterium tumefaciens?

  A bacterial disease that causes galls
• What are some defences against pathogens

  -The skin acts as a barrier to pathogens. It also secretes antimicrobial substances which kill pathogens

  -Hairs and mucus in your nose trap particles that could contain pathogens

  -The trachea and bronchi secrete mucus to trap pathogens

  -The trachea and the bronchi are lined with cilia. These are hair-like structures, which waft the mucus up to the back of the throat where it can be swallowed

  -the stomach produces hydrochloric acid. This kills pathogens that make it far from the mouth
• How does the immune system protect itself from pathogens?

  The most important part of the immune system is the white blood cells. When they come across an invading microbe they have three lines of attack.

  1)consuming them

  2producing antitoxins

  3)producing antibodies

  
• What is phagocytosis?


  Phagocytosis is when white blood engulf foreign cells and digest them

  
• Why do white blood cells produce antitoxins?

  Producing antitoxins counteract toxins produced by the invading bacteria
• Why do white blood cells produce antibodies?

  Every invading pathogen has antigens on its surface. When a white blood cell comes across a foreign antigen, they will start to produce proteins called antibodies to lock onto the invading cells so that they can be found and destroyed by another white blood cell
• How do vaccines work?

  -A weakened or killed form of the disease is injected into the body

  -The body creates antibodies to fight the germs

  -If the actual disease germs ever attack the body, the antibodies return to destroy them. The person is naturally immune to that pathogen and won't get ill
• What are antibodies?


  Proteins that bind to specific antigens on pathogens