AQA biology presentation on pathogens and disease. Please also see youtube video of this being presented here: https://www.youtube.com/watch?v=Wu1Lyn8GjSo

1. Pathogens and
Disease
http://myrevisionnotes.blogspot.com

2. What should I know?
• Pathogens include bacteria, viruses and fungi
• Disease can occur from pathogens entering the body via
an interface
• Interfaces include: digestive and gas exchange systems
• Pathogens cause disease by producing toxins or
damaging host tissues
• Lifestyle can affect health
• Risk factors for CHD and cancer

3. What it boils down to…
• Pathogens
• Pathogen entry into the body
• How a pathogen causes damage
• Lifestyle factors that increase risk of CHD
• Lifestyle factors that increase risk of cancer

4. Pathogens

5. • Viruses
• Bacteria
• Fungi
• A pathogen is a microorganism that gains entry,
colonises the tissues, resists the defences and
causes damages to the tissues of the host

6. How do they get in?!

7. • Through interfaces…
• These include respiratory system (droplets in the
air)
• E.g. TB and Flu
• Digestive system (food and water)
• E.g. Cholera

8. We don’t get ill all the time…
• Our body has defences to prevent pathogens
entering
• Mucous - covers exchange surfaces and forms a
sticky barrier that is hard to penetrate
• Enzymes - break down pathogens
• Stomach acid - very strong and has a low pH so
kills pathogens

9. How do they make us
ill?

10. They cause damage!
• They act by damaging host tissues - theres loads
of them so the sheer numbers burst cells open
• Viruses also act by stopping DNA and RNA
synthesis in cells
• They produce toxins - chemicals that cause
damage
• E.g. cholera produces a toxin that leads to
diarrhoea

11. Lifestyle also plays a
role in disease…

12. Factors that increase the risk
of Cancer
• Smoking
• Diet (if it’s high in fat)
• Obesity
• Low amount of physical activity
• High sunlight exposure

13. Factors that increase the risk
of CHD
• Smoking
• High blood pressure
• High blood cholesterol
• Obesity
• High salt diet
• High saturated fat diet
• Low amount of physical activity

14. Thanks for watching!
notes and more available at http://myrevisionnotes.blogspot.com