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Diseases

Year 10 Biology


Diseases

  • text: Science for Life Ch 4

Assessment:

  • Homework
    • task 1: Disease research
    • task 2: Immunisation research
  • Practical Report
    • Hunting microbes
  • topic test



Find out about a disease...


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Ranking exercise:

  • after you have found out about a range of diseases, take the survey below.
  • did other members in the class think the same way you did?
  • Check out the class results
  • Draw a mind map in your book demonstrating the similarities and differences of the diseases identified by the class. If you are using computer try Xmind / Impress / Word / Graphics program / other..
  • How could we best categorise diseases?


HW task 1: Preparation for class on diseases
  • Investigate a disease in one of these categories and write notes about it ... Use the following points as starters...
    • interesting
    • didn't know
    • info
    • photo
  • Bring the results of your investigation to our next class / email teacher...
  • This task will be graded S/N




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Hepatitis B Virus
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Tetanus
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Tetanus

Class Notes:

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  • What is a disease? (Mind Map)
  • Infectious diseases...
    • Bacterial diseases
    • Viral diseases
    • Protozoa caused diseases
    • Fungal diseases
    • etc
  • Non-infectious diseases...
    • Life-style
    • Genetic
    • Exposure to radiation
    • Exposure to toxins
  • How the body fights disease...
    • Physical defenses
      • Skin
      • Eyes
      • Ears
      • Lungs
      • Nose
      • Digestive system
    • Chemical Defenses
      • pH
      • Antibodies
    • Biological defenses
      • White blood cells
        • Lymphocytes
        • Macrophages



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HIV (AIDS) viral replication in the body's cell

















HW task 2: Preparation for Class on Immunisation

  • Find out what immunizations you have had in your life and when you had them.
  • Find out what diseases they protected you against.
  • Do these diseases still exist in the world?
  • If so, where?
  • Create a fact sheet on one of these diseases.
  • Describe how immunization against this disease works.
  • How and why is it applied at a population level?
  • This task will be graded S/N.

Practical Research:

  • Hunting microbes
    • Aim: to find out where in the school the most microbes can be found.
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      Bacterial colonies
    • Method:
      • Each group is to make 3 Nutrient Agar plates (Petri Dishes)
      • Use cotton buds to swab three surfaces in the school
      • Streak these over the Agar Plates
      • Seal the plates and place them in the incubator to grow for a few days
      • Use the internet to identify what bacteria and fungi you have found.
    • Discussion:
      • Which areas appeared to have the most microbes?
      • How could you tell?
      • Which had the greatest variety of microbes?
      • Where their any surprising results?
      • What potential sources of error where there?fungi.jpg
    • Conclusion:
      • What can you conclude from your research?
  • This task
    • needs to be submitted by Friday 28th / May
    • will be graded in percent.
  • Links:



Immunisation...

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What is immunization? Immunise Australia Program

  • Immunisation protects people against harmful infections before they come into contact with them in the community. Immunisation uses the body’s natural defence mechanism - the immune response - to build resistance to specific infections. Immunisation helps people stay healthy by preventing serious infections.
  • Vaccination Wikipedia
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Why should your child be immunized? MyDr.com.au

  • Being immunised (vaccinated) to protect against catching childhood diseases and other contagious conditions is an important part of your child’s health. Some childhood diseases can have devastating and disabling effects on a child (some of which are permanent), even including death. However, vaccinations give your child immunity to diseases and protect them from suffering from the adverse effects of that disease.
  • The more people who are vaccinated against a specific disease, the smaller the reservoir of available hosts in the population becomes for the disease to live in. This is how diseases such as polio become eradicated in developed countries: by mass immunisation programmes of the population of that country.
  • In the past, Australia had a bad track record for childhood immunisation rates. But according to figures from up to 30 September 2008, 91 per cent of one-year-old children and 93 per cent of 2-year-old children in Australia were fully immunised. However, it is important that immunisation remains a priority for Australian children, so that illnesses such as diphtheria, mumps and hepatitis B are kept under control.

How does immunization work ? Unicef

  • Immunization works by tricking the body into believing it is experiencing a full-scale invasion by an infectious agent so that the immune system can fortify its defenses. During vaccination, a harmless version of a germ is introduced to the body and the immune system responds by producing antibodies to attack the intruder. Thereafter, a memory of this “invasion” remains so that the immune system can quickly recognize and neutralize disease-causing agents when they appear.
  • Active and Passive Immunity Wikipedia
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Why immunization makes sense MyDr.com.au

  • Risks of vaccines compared with risks of illness
  • There is a very small risk of a serious reaction to some vaccines, but this is always much less of a risk than the effects of the disease if contracted. For example:
  • one in 10 people who has the diphtheria vaccine has a fever or inflammation at the injection site, but one in every 15 people who catches diphtheria dies from the disease;
  • about one in every 600,000 people will have a serious allergic response to hepatitis B vaccine, but one in every 4 people who are chronic carriers of hepatitis B will develop cirrhosis of the liver or liver cancer; and
  • one in every 3 million people who get the mumps vaccine will develop mild inflammation of the brain, but one in every 200 children who catch mumps will get inflammation of the brain and one in every 5 males who catch mumps after puberty develops inflammation of the testicles and some of these males become infertile.


Immunisation Schedule in Australia

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New Zealand Immunisation Schedule




The Immune System

The living Medical Textbook

lymphaticsystem.jpg The immune system protects against pathogens that penetrate the physical barriers of the skin and mucous membranes lining the digestive, respiratory, and reproductive tracts. It is subdivided into the innate and the adaptive immune systems. These two systems work differently, but collaboratively, to provide a powerful defense against microbial invaders. Increasing evidence suggests that the immune system also plays a role in detecting and eliminating tumor cells, and can be manipulated therapeutically against cancer.
  • Innate Immunity
    • Macrophages.
      • Macrophages are the "sentinels" of the immune system. Present in large quantities under the skin, in the lungs, and in the tissues surrounding the intestines, these cells are in key positions to detect microbes where they first enter the body.2 The name macrophage means "large eater," and its primary responsibility is to rid the body of debris as well as pathogens, largely but not exclusively via phagocytosis.2,
    • Neutrophils.
      • Neutrophils are highly phagocytic cells. Produced from myeloid precursors and with a lifespan of only 2 to 5 days, these cells circulate through the bloodstream, where they are within easy reach of all cells in the body until they are summoned.
      • Cytokines and chemokines released by macrophages and mast cells draw neutrophils to the area of infection.2,3 It takes only about 30 minutes for neutrophils to exit the bloodstream and arrive fully activated at the site of an infection.2 Once there, they not only perform phagocytosis, they secrete cytokines (eg, TNF) to summon other immune cells and release various antimicrobial products from granules into the extracellular space.
    • Mast cells
      • Mast cells and eosinophils. These cells lie beneath exposed surfaces of the body (ie, the skin and mucosal barriers) and can survive for years. Their best-known function is to provide a defense against parasites. Mast cells are phagocytic and also contain granules of chemicals, most notably histamine. Eosinophils are poor phagocytes but do carry granules. When a mast cell or eosinophil detects a parasite, it "degranulates," that is, it unloads the chemicals.
      • Unfortunately, this not only kills the parasite, but also induces an allergic reaction, and in severe cases, anaphylactic shock.
    • Natural Killer Cells
      • Natural killer cells. After maturation in the bone marrow, natural killer cells await activation in the secondary lymphoid tissues and bloodstream.2 Natural killer cells are activated by certain bacterial cell wall components and also by certain cytokines (eg, interferon [IFN] alpha and IFN beta) secreted by cells infected with viruses. Natural killer cells also can be activated by IL-2. Activated natural killer cells or lymphokine-activated killer cells lyse tumor cells, virus-containing cells, bacteria, parasites, and fungi.2 Cell lysis is accomplished either by puncturing the cell membrane with perforin and then injecting enzymes into the cell or by binding of Fas ligand on the natural killer cell surface to Fas on the target cell surface, thereby triggering apoptosis.2,4 Natural killer cells also release cytokines, including IFN gamma, TNF alpha, and granulocyte colony-stimulating factor.4
    • Complement system
      • Complement system. The innate immune system also includes the complement system, consisting of about 20 proteins produced mainly by the liver.2 These proteins include proteolytic enzymes, inflammatory and regulatory proteins that summon or enhance the activity of phagocytic cells in both the innate and adaptive immune systems, and lytic proteins that attack cell surface membranes.2,6 The complement system also opsonizes viruses that are outside of cells for phagocytosis and penetrates the membranes of enveloped viruses.2

  • Adaptive Immunity
    • Characteristics of the Adaptive Immune Response
      • The adaptive immune system is an initially slow but highly specific source of immunity.1 The adaptive immune system evolved later than–and from–the innate immune system in the course of evolution, is found only in jawed vertebrates, and is at its most sophisticated in humans.2,7 The adaptive system theoretically has the ability to defend against virtually any pathogen.2 Furthermore, the adaptive system has the ability to "remember" pathogens it has already been exposed to, which greatly speeds its reaction time to subsequent exposures, thereby providing lasting immunity, or "memory".
    • Cells of the Adaptive Immune Response
      • Dendritic cells
      • B-cells and the antibodies they produce.
      • T-cells.


..and cancer
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Normally the body is able to remove cancer cells... but sometimes something happens which impedes this process...
  • Why People Get Cancer
    • People get cancer because one of three things happens (and more often than not all three together):
    • You expose yourself to toxins and outside influences (such as heavy metals, radiation, rancid fats, viruses, bacteria, parasites, etc.) that dramatically increase the number of cancerous cells your body produces so that not even a healthy immune system can handle the load.
    • You compromise your immune system (or age takes a toll) to the point that it can no longer handle all of the cancerous cells your body produces, thus allowing some of them to take root and establish themselves.
    • Your circulation (blood, lymph, energy) is impeded --thus leading to both 1 and 2 above.

    ----

On the Origin of the Immune System


With swine flu circulating the globe, it’s appropriate that May’s Origins essay is “On the Origin of the Immune System.” Immunology is the study of how we and other animals defend ourselves against pathogenic microorganisms—bacteria, viruses, and parasites, for example—and this battle goes back to the beginning of evolution. The first multicellular creatures must have had to learn how to be nice to their own cells yet attack any invading cell trying to exploit their resources. Indeed, when biologists look at sponges and other “simple” creatures at the base of the evolutionary tree, they see many of the same microbial defenses that we and other complex animals use, which suggests that at least some form of immunity arose very quickly in the evolution of animals. But those ancient defenses only constitute what scientists call the innate immune response, an all-out molecular and cellular assault on infected tissue. Most vertebrates have a second level of defense, the adaptive immune response, that targets, and remembers, specific microbes. It’s this adaptive immune response, dependent on white blood cells called B and T cells, that physicians elicit when they vaccinate a person against a virus, for example. In a scientific detective story that has played out over the past few decades, researchers have shown how this adaptive immune response arose after innate immunity, and they have teased out the details of the fortuitous event, a random DNA insertion in an opportune spot, that was the key to its birth. The research on this “big bang of immunology” even played a key role in a 2005 trial pitting scientists and educators against those doubting evolution and seeking to diminish its teaching in school systems in the United States.
John Travis
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Illustration: Katharine Sutliff/Science







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