Health and Disease

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  • Health and Disease
    • Good health is a state of physical and mental wellbeing
    • DISEASE
      • Virus, Bacteria, Fungi, Protist
        • Viruses: reproduce rapidly causing damage to your cells
          • Measles
            • Symptoms include fever and red skin rash
            • spread by breathing in droplets from sneezes/coughs
            • Can be fatal so children vaccinated against it
          • HIV (human immunodeficiency virus)
            • Spread by sexual contact or exchange of bodily fluids
            • Flu like illness at first
            • If untreated can attack immune system through lymphnodes
            • Taking antiviral drugs can delay this happening
            • Last stage HIV become AIDS and the immune system can no lonher fight off any infections e.g. cancer
        • Bacterial diseases can damage cells and produce toxins that damage tissues
          • Salmonella
            • type of food poisoning cause by bacteria
            • bacteria then secrete toxins which cause fever, abdominal cramps, vomiting and diahoea
            • Chicken and eggs contain nit so they are vaccinated against it
          • Gonnorrhoea
            • sexually transmitted disease cause by bacteria
            • symptoms include think yellow/green discharge and pain when urinating
            • used to be easily treated but resistant strains have now appeared
            • prevented through use of barrier method e.g. condoms
        • Protists and disease
          • Protists are single celled organisms that are eukaryotic
          • Malaria
            • protist uses particular type of mosquito as a vector
            • Passed to a person when they are bittten
            • causes severe fever which reoccurs and can be fatal
            • To prevent by using mosquito nets and killing the mosquitos
        • Fungal disease
          • Rose black spot
            • spread when spores are carried from plant to plant by water/wind
            • Purple or    black spots develop on leaves which turn yellow and drop early
            • Loss of leaves would stunt growth s photosynthesis is reduced
            • Can be treated using fungicides and removing/destroying affected leaves.
      • Communicable and non-communicabel
        • Communicable - Can be spread between organisms
        • Non-communicable - Cannot be spread between organisms
      • Can also interact :
        • Viruses infecting cells can trigger cancers
        • Diseases of the immune reaction meaning people are more likely to get other diseases e.g. HIV and tuberculosis
        • Immune reactions triggered by pathogens can cause allergies e.g.asthma
        • Being physically ill can lead to depression/mental illness
        • Life situations (poor diet, stress) can increase chance of getting certain diseases
      • RISK FACTORS!!
        • lack of exercise/ smoking/high intake of saturated fat/obesity/excessive alcohol intake/ionising radiation/smoking and drinking during pregnancy.
      • Diseases of the Heart
        • Coronary heart disease
      • Cancer
        • Caused by uncontrolled cell division that form messes called tumours/
          • Benign tumours do not spread around the body
          • Malignant tumours spread in the blodd to different parts of the body and form secondary tumous.
        • Lifestyle risk factors include smoking and obesity, there are also genetic risk factors that may run in families
    • HUMAN DEFENCES
      • Non-specific defences
        • Skin - sebaceous gland produces sebum which kills bacteria and fungi
        • Glands in stomach walls produce hydrochloric acid which kills bacteria in food
        • Enzymes in tears destroy microorganisms
        • The nose traps particles that may contains pathogens
      • THE IMMUNE SYSTEM
        • If a pathogen enters the body the immune system tries to destroy it
        • White blood cells help to defend against pathogens through PHAGOCYTOSIS, which involves the pathogen being engulfed and digested.
          • 1. Microorganisms invade the body
          • 2. the white blood cell finds the microorganism and engulfs them
          • 3. The white blood cell ingests the microorganism
          • 4. the microorganism has been digested and destroyed
        • The production of a special protein molecule called ANTIBODIES which attach to the antigen molecules on the pathogen
          • 1. Antigens are markers on the surface of the microorganism
          • 2. The white blood cell become sensitised to the antigens and produce antibodies
          • 3.The antibodies then lock onto the antigens
          • 4. This causes the microorganisms to clump together, so that other white blood cells can digest them
      • Boosting immuntiy
        • If the same pathogens re-enters the body the white blood cells respond quicker and produce antibodies
        • When a person has a VACCINATION small quantites of dead or inactive forms of a pathogen are injected into the body which stimulates the WBC to produce antibodies and develop immunity.
        • If a large proportion of the population can be made immune to a pathogen then it cannot spread very easily.
    • Treating disease
      • Antibiotics are medicines used to kill bacteria inside the body but CANNOT DESTROY VIRUSES!
      • The use of antibiotics has greatly reduced deaths from infection
      • Bacterial strains resistant to antibiotics are increasing so they should not be prescribed unless really need, for non-serious infections or for viral infections.
      • Patient must complete the entire course of antibiotics prescribed so that all the bacteria are killed and none survive to form resistant strains
    • Developing new drugs
      • constant demand for new drugs
      • Traditionally drugs were extracted from plants
        • Digitalis from foxglove
        • Aspirin from willow
        • Penicillin from the Penicillium mould
      • New medical drugs have to be tested and trialled before used to make sure they are safe and not toxic, is it safe for animals?, is it safe for humans?
        • see if it works
        • find out the optimum dose
      • DOUBLE BLIND TRIALS
        • Some patients are given a placebo which does not contain the drug, others are given the drug but neither the patient nor the doctor know who gets what.
      • MOMOCLONAL ANTIBODIES
        • produced from a single cell that has divided to make clones of itself.
        • used to bind to a specific antigen
        • A mouse is vaccinated with the target antigen then the antibodies produced from the B cells in the spleen are removed and fused with tumour cellsto from hybridoma cells which are able to divide.  Anti-body forming cells are selected and then monoclonal antibodies are collected.
        • Can be used for pregnancy tests, in labatories, in research and to treat some diseases such as cancer
    • Plant diseases
      • Indentifying
        • stunted growth
        • spots on leaves
        • areas of decay(rot)
        • growths
        • malformed stems or leaves
        • discolouration
        • the presence of pests
        • consulting a gardening manual/website
        • taking the infected plants to a  lab to identify pathogen
        • using testing kit, which contain monoclonal antibodies
      • Plants ca suffer from communicable/non-communicable diseases
      • They can be infected by a range of viral, bacterial and fungal pathogens as well as by insects.
      • Tobacco Mosaic Virsus (TMV)
        • infects tobacco and tomato plants
        • produces distinctive 'mosaic'pattern of discolouration on the leaves, reduces chlorophyll content and affects photosynthesis
        • affects growth due to lack of photosynthesis
      • Aphids
        • small insects (greenfly/blackfly), feed on phloem taking sugars away from the plant
      • Deficiency diseases
        • stunted growth caused by NITRATE DEFICIENCY, nitrate is needed for photosynthesis
        • Chlorosis caused by MAGNESIUM DEFICIENCY magnesium ions are needed to make the chlorophyll.
      • Plant Defences
        • Cellulose cell walls
        • tough waxy cuticle on leaves
        • layers of dead cells around stems(bark)
        • antibacterial chemicals
        • poisons to eter herbivores
        • mechanical adaptations - thorns hairs; leaves that droop/curl when touched/mimicry to trick animals

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