Biology B4

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Health and Disease

  • Physical well-being:
    • Not getting ill
    • Taking regular exercise
    • Eating a balanced diet
    • Not smoking
    • Not taking drugs
    • Not drinking too much
  • Social well-being:
    • Having friend
    • Being comfortable with your home and where you work 
    • Being a member of a well functioning community 
  • Mental well-being:
    • Good sel-esteeem 
    • Able to manage 'normal' stress 
    • Able to relax 
    • Able to take responsibilty for yourselves 
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Communicable and Non-communcable diseases

  • Communicable disease can be passed to person to person e.g. colds
  • Non-communicable disease cannot be passed from person to person e.g. mental health

Diseases may be correlated, so that having one disease means that a person is more likely to have another disease. Possible causes of these correlations include:

  • One disease damages the immune system, making it easier for other pathogens to cause disease (the immune system protectst the body from communicable diseases; one pathogen that attacks the immune system is HIV).
  • A disease damages the body's natural barriers and defences, allowing pathogens to get into the body more easily.
  • A disease stops an organ system from working effectively, making other diseases more likely to occur.
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Heart Disease

Danger Signs

  • Many times no symptoms until blood vessels get damaged.
  • Angina- tightness and pain in the chest.
  • Heart palpatations
  • Fainting
  • Puffiness
  • Breathlessness
  • Fingernails have a blue tinge
  • Fatigue

Genetic Risk Factors

  • Family history
  • Increases with age
  • Blacks and Asians
  • Diabetics are three times more likely
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Heart Disease 2

Atherosclorosis

  • Occurs when arteries get clogged with fat 
  • Process of narrowing cells

Prevention

  • Don't smoke
  • Lose weight
  • Exercise under the care of a physician
  • Keep blood chlorestol low
  • Keep blood pressure under control
  • Follow a low fat diet
  • Regular medical checkups
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Pathogens and Viruses

Different diseases caused by pathogens:

Tubercolosis:

  • Symptom: weight loss, fatigue, chills and night sweats, long term cough, coughing up blood, chest pain
  • Pathogen: Mycobacterium tuberculosis or mycobacterium bovis 

Chlamydia

  • Symptoms: enlarged testes, urinate frequently, infertility, burning and itching
  • Pathogen: Chlamydia, bacteria

Malaria

  • Symptoms: Muscle pain, high temperature, back pains, vomiting, nausea
  • Pathogen: Plasodium 
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Viruses

  • Viruses are not true organisms because they do not have cellular structure.
  • They multiply by ingecting a cell and tkaing over the cells DNA copying process to make new viruses.
  • Viruses are unable to replicate on their own.
  • They have to enter a living cell and take over that cells processes.
  • Different types of virus take over different types of cells and proteins.
  • Viruses all have certain features in common.
  • All viruses contain one or more strands of genetic material surround by a protein coat.
  • The cell copies the vital genetic material and proteins.
  • Some types of virus cause the complete breakdown of the cell, or lysis.
  • Some viruses that cause lysis go through a lytic pathway during the life cycle.
  • Every time the cell divides, the virus' genetic material is replicated with the cell's genetic material. This is called lysogenic pathway.
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Viruses 2

  • At some point viruses genetic material triggers the copying of itself and the making of viral proteins, and the virus returns to its lytic pathway.
  • The effects of viruses on bacteria can be studied using bacterial lawn plates.
  • These plates are made with nutrient agar, and a thin layer of bacteria grows on top.
  • After a day or two, clear circles can be seen where bacteria have been killed by the virsuses.
  • The cross-sectional area of a clear circle is calculated using the equation:

cross sectional area= r2 (where r=radius)

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Antibiotics

Antibiotics are medicines used to treat bacterial infections

Bacteriostatic antiobiotics slow the growth of bacteria by intefering with the three processes it needs to grow- DNA replication, metabolism and protein production.

Bactericidal antibiotics kill bacteria by preventing the bacteria from making a cell wall. An example of bactericidal antibiotics is penicillin. Penicillin V is used for sore throats, Amoxicillin is used for chest infections and flucloxacillin is used for skin infections.

A negative impact of broad spectrum antibiotics is that it kills useful bacteria inside the body such as the ones inside your gut.

But why do they not work on viruses?

Bacteriostatic: Do not attack bodily cells and does not slow down the growth of viruses

Bactericidal: Viruses do not have a cell wall, and bactericidal antibiotics break down a bacteria's cell wall.

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Monoclonal Antibodies

Monoclonal antibodies are identical copies of antibodies that have been made in laboratories.

(http://www.vce.bioninja.com.au/_Media/monoclonal_antibodies_med.jpeg)

They have a number of different uses:

  • Pregnancy tests
  • Diagnosing cancer
  • Treating cancer 

They need to be in large numbers to work properly.

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Developing New Medicines

The process of developing a medicine:

  • Identify the disease/ pathogen
  • Cells/ tissue culture as a model of disease
  • Animal testing- give them a specific amount; look at side effects and safety
  • Phase 1: 20-100 healthy volunteers, sometimes people with the disease or condition= side effects, safety, done with dosages
  • Phase 2: tested on people with the disease, making sure it does what they expect, finding the best dose, tests several hundred people, side effects and safety
  • Phase 3: 300-3,000 people tested, volunteers with disease, takes 4 years, long term side effects, can extend time given, more accurate results, undetected common side effects, considers disease progression
  • Phase 4: safe, FDA approved,effective, side effects are minimal.
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The Placebo Effect

It is important to be certain that a drug really does have positive effects, rather than people feeling better simply because they expect to feel better if they take a medicine. This is the placebo effect.

Single blind- you don't know what the doctor is giving you, but the doctor knows.

Double blind- neither you nor the doctor knows.

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Plants Transmitting Diseases

Plants can transmit diseases...

  • Directly
  • Indirectly
  • Spores (fungi)
  • Animal vectors such as elm bark beetles, aphids and birds

What effects transmission?

  • Choice of plant species
  • Overcrowding
  • Poor availability of minerals
  • Damp, warm conditions
  • Farming practices
  • Import and export
  • Climate change: increased rainfall, allows some vectors to spread, drier conditions reduce spread of diseases.
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Plant Barriers Against Disease

Physical Barriers

  • Waxy cuticule on leaves
  • Bark on trees
  • Cellulose cell wall
  • Lignified cell wall
  • Callus formation (like scars)

Physical Defence

  • Rapid, unspecific response to invasion by pathogen 
  • Callose is synthesised and deposited between the cell wall and cell membrane, also at the plasmodesmata
  • Thickening and deposition of lingin increase the effectiveness of the mechanical barrier.
  • Callose also blocks sieve plates in the phloem, sealing off the infected cells and preventing spread via this transport system.
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Plant Defences

Insect repellents: Citronell from lemon grass plants and pine resin from pine trees are effective insect repellents.

Insecticides: Pyrethin produced chrysanthemums are used as insecticides. They are neurotoxins.

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