health and disease

• The immune system is the body's defense against infection, illness, and foreign substances.
• Inflammation is the body's response to injury or infection, characterized by redness, swelling, heat, pain, and loss of function.
• Immune cells are specialized white blood cells that defend the body from pathogens and other threats.
• Antibodies are proteins produced by B lymphocytes (B cells) that bind to specific antigens on pathogens and mark them for destruction.
• T lymphocytes (T cells) play a role in cell-mediated immunity, which involves attacking infected cells directly rather than producing antibodies.
• Natural killer cells are a type of T cell that can kill virus-infected cells without prior exposure to the virus.
• Natural killer cells are a type of lymphocyte that can recognize and kill cancerous or virus-infected cells without prior exposure.
• The immune system has two main types of responses: innate immunity and adaptive immunity.
• Innate immunity provides immediate protection against foreign invaders through physical barriers like skin and mucus membranes, as well as chemical defenses such as acidic pH levels and enzymes.
• Adaptive immunity develops over time and provides long-lasting protection against specific pathogens through the production of memory cells.
• neurons have three main regions - dendrites, cell body and axon
• the nervous system is made up of the brain, spinal cord and nerves
• cell bodies contain nuclei and organelles
• axons transmit electrical impulses away from the cell body
• synapses are gaps between nerve endings where neurotransmitters pass messages across
• health = according to WHO, health is a state of total social, mental and physical wellbeing
• disease = a disorder of the body or mind that negatively affects an individuals health
• communicable disease = can be spread though direct contact, caused by pathogen e.g. flu or HIV

  
  

  non communicable disease = can't be spread from person to person, is generally long lasting and is usually caused by lifestyle, environmental conditions, genetic mutations etc. some examples are cancer or cardiovascular dieseases
• pathogen = disease causing organism e.g. virus, fungi, bacteria, protist
• describe cholera :

  • caused by vibrio cholerae bacterium
  • spread by drinking water/washing in contaminated water
  • symptoms = diahrea and vomiting

  prevent/reduce cholera outbreaks by giving people access to clean water and improving sanitation (sewage disposal etc.)
• describe tuberculosis :

  • caused by Mycobacterium tuberculosis bacterium
  • is airborne, bacteria spread through droplet infection (coughing/sneezing)
  • symptoms = lung damage, chesty cough, wheezing

  reduce transmission by - improving hygiene, infected individual avoid crowded areas, increase ventilation in home
• chalara ash dieback :

  • caused by fungus from ash trees
  • spread via airborne, carried by wind
  • causes dark lesions on bark and blackens leaves which wilt and eventually die

  transmission reduced by - control movement of ash tree, kill infected plant, replant with different species
• malaria :

  • caused by plasmodium protist
  • spread by mosquito vector, it picks up the protist when feeding on blood and transmits the malaria to other organisms when feeding on them
  • flu like symptoms, damage to red blood cells, liver damage

  reduced - mosquito nets, insect repellant, cover arm and legs to avoid being bitten
• stomach ulcers :

  • caused, helicobacter pylori bacterium
  • transmitted orally, eating infected food or drink
  • symptom are stomach pain, vomiting/nausea

  reduced by - access to clean water, improve hygiene and sanitation
• ebola :

  • caused by ebola virus
  • spread through direct contact, body fluids e.g. blood, semen, saliva, mucus, vomit~
  • symptoms are fever, diarrhoea, vomiting, internal bleeding

  transmission reduced - improve hygiene, isolate infected person, sterilised areas of outbreak
• how do viruses cause disease ?

  enter host cell and replicate in them, the host cell ruptures releasing the new virus
• describe lytic pathway :

  1. virus binds to specific receptors on host cell
  2. virus injects its DNA into host cell and replicates its DNA using host cell machinery
  3. new coral structures are produced and assembled
  4. shot cell ruptures, releasing the new viruses
• describe lysogenic pathway :

  1. virus binds to specific receptor on host cell
  2. viral DNA injected into host cell and becomes integrated into host cell genome (the complete set of genetic information of an organism.)
  3. viral DNA replicates each time the host cell divides. However cell remains normal
  4. trigger causes the activation of viral DNA. it enters the lytic pathway
• describe HIV :

  • caused by human immunodeficiency virus
  • spread by direct contact with infected body fluids
  • destroys white blood cells making person immunodeficient and increasingly susceptible to things like AIDS

  spread reduced - protected sex, needle exchange stopped, screening blood for HIV and deterring infected mother from breast feeding
• describe chlamydia :

  • caused by chlamydia bacterium
  • spread bus sexual contct
  • can result in infertility

  transmission reduced - protected sex and screening