GCSE Biology: Infection and response

• Viruses are very small
• Viruses use biochemistry to make copies of itself
• Viruses cause the cell to burst and release its copies into the blood stream
• Cell destruction makes us feel ill
• Bacteria multiply quick through binary fission
• Bacteria produces cell damaging toxins
• Protists use humans and animals as their hosts
• Fungi can be single felled or be bad or hyphae
• Infectious disease


  A disease that is caused by a pathogen and that can be spread from one individual to another.

  
• Non infectious disease


  A disease caused by the body malfunctioning, lifestyle or environment

  
• Pathogens

  Is a micro organism that causes diseases eg virus bacteria fungi protists

  
• Bacteria

  Are prokaryotes, they are tiny cells which reproduce rapidly in your body.

  
• Bacteria cause harm by

  multiplying in the body, producing toxins which harm your body cells

  
• Viruses are..

  Not cells, and are so small they have to be viewed with an electron microscope

  
• Viruses can't...

  be killed by antibiotics

  
• How do viruses cause harm?

  By getting inside cells and bursting the cells open

  
• Airborne infection


  Cough sneezing breathing (e.g cold/flu/measles)

  
• Direct contact


  Sex and skin to skin (gonorrhoea/HIV)

  
• Contaminated food and drink

  Eating contaminated food, not properly cooked (Salmonella)

  
• pathogens can enter Through a break in skin

  Cuts scratches

  
• If a pathogen enters the body...

  Immune white blood cells help to defend by ingesting.

  
• White blood cells


  Blood cells that perform the function of destroying disease-causing microorganisms.

  
• What are vectors?

  Small organisms that carry pathogens from person to person eg mosquitoes that carry the malaria protist

  
• What are vaccinations?

  Involves introducing small amount of dead/inactive pathogens to stimulate WBC to produce antibodies

  
• How do vaccinations work?


  The body will produce antibodies quickly when it sees the infection again. The fast immune response helps fight the pathogen faster

  
• Antibiotics are...

  Are used to cure bacterial disease (e.g. penicillin)

  
• How do antibiotics work?

  Damage the bacterial cells without damaging your own cells

  
• Name the advantages and disadvantages of antibiotics

  They treat most bacterial infections.They cannot treat viruses.Some bacteria are becoming immune to certain antibiotics.

  
• Antiseptic


  A substance that destroys micro-organisms that carry disease without harming body tissues

  
• Blood clots


  form around injury site to prevent any microbes or their toxins from entering the body

  
• Stomach acid

  Hydrochloric acid kills pathogens in stomach

  
• Skin


  Physical barrier to protect against pathogens

  
• Mucus and cilia (tiny hairs)

  Mucus traps pathogens and cilia waft mucus towards the throat to be swallowed into the stomach (and destroyed by acid)

  
• White blood cells produce antibodies...


  to specific antigens (markers on the surface of a pathogen)

  
• Bacteria can become...

  Resistant to antibiotics from random mutations

  
• Drugs are tested by

  1) in lab on cells ) on animals ) on volunteers ) on patients

  
• Vaccines provide

  herd immunity and stops spread of pathogen even among those who are not vaccinated

  
• Gonorrhoea symptoms

  Greenish discharge from vagina or penis, burning during urination

  
• Dosage


  The concentration of the medicine and how often it should be taken

  
• double blind trial


  when neither researchers nor participants are aware of who's in the experimental or control group