B3- infection and response

• Pathogens are microorganisms such as bacteria, viruses or fungi that can cause disease
• Bacteria are very small living cells

  they can reproduce in your body

  they produce toxins that damage your cells and tissues
• viruses are not cells

  similarly to bacterium, they reproduce rapidly in your body

  they live in your cells and replicate themselves

  this damages the cell, making you feel unwell
• Protists are single-called eukaryotes

  there are many types of protists

  some are parasites. Parasites live on or inside another organism and causes damage

  often transferred through a vector who doesn’t get the disease themselves
• Fungi come in different shapes

  some are single-celled, others have bodies made of hyphae

  hyphae can grow and penetrate human skin and the surface of plants - causing disease

  hyphae can produce spores. Can spread to other plants and animals
• hyphae is a thread like structure that makes up some fungi
• Pathogens can be transmitted through

  • WATER: drinking or bathing in dirty water, e.g cholera, a bacterial infection spread by drinking contaminated water
  • AIR: can be carried by air and breathed in. Some airborne pathogens are carried in droplets produced through a cough or sneeze, e.g influs virus causing the flu.
  • DIRECT CONTACT: some are picked up though touching contaminated surfaces including skin, e.g athlete‘s foot is fungal. Commonly spread by touching same surfaces as the infected person.
• VECTOR: insects carry diseases from one place to another. E.g mosquitoes carrying malaria. The mosquito bites an infected animal then bites someone else spreading the disease
• FOOD AND DRINKS: food poisoning caused by bacteria such as salmonella, which lives in raw meat. Food poisoning occurs when we eat undercooked food containing these bacteria.
• VACCINATION: involves injecting a small amount of dead or weakened microorganisms into the bloodstream. This stimulates the immune system to make antibodies against the specific antigen. If the real pathogen enters the body later, the immune system will recognise it and destroy it quickly
• ANTIBIOTICS: drugs used to treat bacterial infections. They kill bacteria by disrupting their metabolism. However, overuse has led to resistance where bacteria evolve to survive despite exposure to antibiotics
• ANTIBIOTICS: drugs used to treat bacterial infections. They kill bacteria by disrupting their cell walls so they burst open. Antibiotics do not work on viruses because viruses don’t have cells with cell walls
• IMMUNE RESPONSE: the way our body fights off invading organisms. It consists of two types of responses; non-specific (innate) and specific (adaptive)
• ADAPTIVE IMMUNITY: also known as acquired immunity. Produced by lymphocytes. Takes time to develop but provides long term protection. Can be active or passive