Pathogens and Disease

http://myrevisionnotes.blogspot.com

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

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

Pathogens

• 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

How do they get in?!

• Through interfaces…

• These include respiratory system (droplets in the air)

• E.g. TB and Flu

• Digestive system (food and water)

• E.g. Cholera

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

How do they make us ill?

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

Lifestyle also plays a role in disease…

Factors that increase the risk of Cancer

• Smoking

• Diet (if it’s high in fat)

• Obesity

• Low amount of physical activity

• High sunlight exposure

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

Thanks for watching!notes and more available at

http://myrevisionnotes.blogspot.com