Defence mechanismsLesson Objectives.

To describe how pathogens might get into the body andhow the body has different ways of preventing this entry.

Using the worksheet try to explain how these infection types cause infection; Droplet, Direct contact, Contaminated food and drink, Trough a break in your skin.

Then match these examples to the correct one.Flu (influenza), HIV/AIDS, salmonella, impetigo (skin disease), tuberculosis, genital herpes, diarrhoea, hepatitis, common cold,

Infection type How pathogens enter the body Examples

Droplet infection

Coughing, sneezing or talking expels tiny droplets full of pathogens. Other people

breathe in these droplets and become infected.

Flu (influenza)

Tuberculosis

Common cold.

Direct contactThe pathogen touches the skin/

area of infection directly.

Impetigo

Genital herpes

Contaminated food and drink

The person ingests the pathogens in large numbers

straight into the gut.

Diarrhoea

Salmonella

Through a break in your skin

Pathogens can enter your body through cuts, scratches or

needle punctures.

HIV/AIDS

Hepatitis.

Homework

• What was the problem with thalidomide in the 1960s?

• Find out information about this drug and the problems associated.

• What happens to a drug before it is released to the general public?

• Why was thalidomide a problem even though these procedures were carried out?

What do platelets do?

• Your skin is a very important barrier protecting the body from infections.

• If your skin gets damaged you bleed.

• Platelets in the blood quickly help to form a clot which dries into a scab. These scabs act as a barrier until the skin heals.

What happens when your blood does not clot?

• Haemophilia is a condition where the blood does not clot properly.

• These means they bleed more than other people when they are injured.

Role of white blood cells

How it protects you against disease

Ingesting microorganisms

Some white blood cells ingest (take in) pathogens, destroying them and preventing them from causing disease.

Role of white blood cells

How it protects you against disease

Ingesting microorganisms

Some white blood cells ingest (take in) pathogens, destroying them and preventing them from causing disease.

Producing antibodies

Some white blood cells produce special chemicals called antibodies. These target particular bacteria or viruses and destroy them. Each type of pathogen needs a unique antibody. Once your white blood cells have made the unique antibody they can make them very quickly next time the pathogen enters the body.

Role of white blood cells

How it protects you against disease

Ingesting microorganisms

Some white blood cells ingest (take in) pathogens, destroying them and preventing them from causing disease.

Producing antibodies Some white blood cells produce special chemicals called antibodies. These target particular bacteria or viruses and destroy them. Each type of pathogen needs a unique antibody. Once your white blood cells have made the unique antibody they can make them very quickly next time the pathogen enters the body.

Producing antitoxins Some white blood cells produce antitoxins. These counteract the toxins released by pathogens.

Why was disease spread so easily in the London Slums?