SB5 bio edexcel

• Health


  The complete social, physical and mental well-being of a person
• Disease


  Any change in the normal function of a part of the body
• Types of diseases


  • Communicable
  • Non-communicable
• Communicable diseases


  Can be spread from person to person
• Non-communicable diseases


  Cannot be spread from person to person, mainly caused by lifestyle or genetics
• Causes of communicable diseases

  • Pathogens (microorganisms that can cause disease)
  • Bacteria (e.g. cholera, tuberculosis)
  • Fungi (e.g. chlora diet ashbach)
  • Protists (e.g. malaria)
  • Viruses (e.g. HIV, chlamydia)
• Vectors


  Something that has the disease and spreads it onto something else (e.g. mosquitoes for malaria)
• Viruses


  Pathogens made up of genetic material (DNA or RNA) surrounded by a protein coat
• Viruses


  • They don't have any of the structures that cells have (e.g. ribosomes)
  • They can't reproduce themselves, they have to use living cells to replicate
• Lytic pathway of virus replication

  1. Virus inserts genetic material into cell

  2. Virus uses cell parts to make new viruses

  3. Cell lyses (explodes) releasing new viruses
• Lysogenic pathway of virus replication

  1. Virus inserts genetic material into cell's DNA

  2. Virus genetic material replicates as cell divides

  3. Trigger causes virus to enter lytic cycle
• Barriers to pathogens in the human body

  • Physical barriers (skin, mucus, cilia)
  • Chemical barriers (stomach acid, lysozyme)
• Immune system


  Made up of white blood cells (phagocytes and lymphocytes)
• Lymphocytes


  White blood cells that produce antibodies
• Antigens


  Molecular flags on cells that identify them as 'self' or 'foreign'
• Antibodies


  Produced by lymphocytes, have a specific shape to bind to antigens and destroy pathogens
• Vaccines


  Contain dead or weakened pathogens to stimulate an immune response
• Drug development process


  1. Pre-clinical trials (testing on human tissue, then animals)

  2. Clinical trials (testing on healthy humans, then ill humans)
• Efficacy


  How well a drug works
• Toxicity


  Side effects of a drug
• Causes of non-communicable diseases

  • Lifestyle choices (e.g. obesity, smoking)
  • Genetics
• Obesity


  Measured by BMI (body mass index) and waist-to-hip ratio
• Smoking


  Leads to fatty buildup in arteries, restricting blood flow and causing cardiovascular disease
• Cardiovascular disease (CVD)


  Problems with the heart or blood vessels
• Treatments for CVD


  • Stents
  • Statins
• Plant defences


  • Waxy cuticle on leaves
  • Cell walls