starter (from the end of last lesson) 1.what are the similarities between a virus and bacteria? 2....
TRANSCRIPT
Starter (from the end of last lesson)• 1.What are the similarities between a
virus and bacteria?• 2. What are the main differences
between a virus and bacteria?• 3. Draw a flow diagram to explain how
viruses replicate.• 4. Name three viral diseases.• 5. Why are viral diseases much harder
to treat than bacterial diseases?
1. How are diseases spread?
Title: Defence Mechanisms
3. How do white blood cells protect
us from disease?
2. How does your body
stop pathogens getting in?
Ways of Spreading Diseases
There are four main ways that pathogens are spread from one person to another.
1. How are diseases spread?
Defence Mechanisms
3. How do white blood cells protect
us from disease?
2. How does your body
stop pathogens getting in? • Droplet Infection
• Direct Contact• Contaminated Food and Drink• Through a break in the skin
Droplet Infection• When you cough, sneeze or talk, tiny droplets
full of pathogens are expelled into the air. Other people breathe these in.
• E.g. Tuberculosis, Influenze, Common Cold
1. How are diseases spread?
Defence Mechanisms
3. How do white blood cells protect
us from disease?
2. How does your body
stop pathogens getting in?
Direct Contact• Some diseases spread by direct contact
of the skin. • e.g. Impetigo, Genital Herpes
1. How are diseases spread?
Defence Mechanisms
3. How do white blood cells protect
us from disease?
2.How does your body
stop pathogens getting in?
Contaminated Food and Drink• Eating raw or undercooked food, or
drinking water containing sewage can spread disease.
• E.g. Salmonella, Cholera
1. How are diseases spread?
Defence Mechanisms
3. How do white blood cells protect
us from disease?
2. How does your body
stop pathogens getting in?
Through a Break in the SkinPathogens can enter the body through
cuts, scratches and needle puncturesE.g. HIV, Hepatitis
1. How are diseases spread?
Defence Mechanisms
3. How do white blood cells protect
us from disease?
2. How does your body
stop pathogens getting in?
Task 1
• Describe the four main ways in which infectious diseases are spread.
1. How are diseases spread?
Defence Mechanisms
3. How do white blood cells protect
us from disease?
2. How does your body
stop pathogens getting in?
Preventing Microbes Getting In
• There are three main barriers to infection.
1. How are diseases spread?
Defence Mechanisms
3. How do white blood cells protect
us from disease?
2.How does your body
stop pathogens getting in?
• The Skin• Scabbing
• Mucus and Stomach Acid
Preventing Microbes Getting In• The skin prevents bacteria and viruses
from getting to your tissues underneath.
1. How are diseases spread?
Defence Mechanisms
3. How do white blood cells protect
us from disease?
2. How does your body
stop pathogens getting in?
Preventing Microbes Getting In• If you cut your skin, you bleed. Your
blood quickly clots and forms a scab. This prevents any pathogens from entering.
1. How are diseases spread?
Defence Mechanisms
3. How do white blood cells protect
us from disease?
2. How does your body
stop pathogens getting in?
Preventing Microbes Getting In• When you breathe, you draw in air full
of pathogens. Your breathing system produces mucus which traps them.
1. How are diseases spread?
Defence Mechanisms
3. How do white blood cells protect
us from disease?
2. How does your body
stop pathogens getting in?
Preventing Microbes Getting In• The mucus can then be removed from
the body (blowing your nose) or swallowed into the gut, where stomach acid destroys the pathogens.
1. How are diseases spread?
Defence Mechanisms
3. How do white blood cells protect
us from disease?
2.How does your body
stop pathogens getting in?
Task 2• Copy and complete the following table
1. How are diseases spread?
Defence Mechanisms
3. How do white blood cells protect
us from disease?
2.How does your body
stop pathogens getting in?
Barrier How it protects against infection
Skin
Scabbing
Mucus and Stomach Acid
• Some pathogens still get through the barriers to infection. The body however has a second line of defence - the white blood cells of the immune system.
1. How are diseases spread?
Defence Mechanisms
3. How do white blood cells protect
us from disease?
2. How does your body
stop pathogens getting in?
How White Blood Cells Protect Against Disease
• White blood cells protect fight pathogens in three main ways.
1. How are diseases spread?
Defence Mechanisms
3. How do white blood cells protect
us from disease?
2. How does your body
stop pathogens getting in?
How White Blood Cells Protect Against Disease
• Ingesting Microorganisms• Producing Antibodies• Producing Antitoxins
• Some white blood cells ingest (take in) pathogens, destroying them so they can’t make you ill.
1. How are diseases spread?
Defence Mechanisms
3. How do white blood cells protect
us from disease?
2. How does your body
stop pathogens getting in?
Ingesting Microorganisms
• Some white blood cells produce antibodies that bind to antigens on bacteria and viruses and destroy them.
1. How are diseases spread?
Defence Mechanisms
3. How do white blood cells protect
us from disease?
2. How does your body
stop pathogens getting in?
Producing Antibodies
• Once your white blood cells have made an antibody for a specific pathogen, if you get re-infected, these antibodies can be made very quickly. This is immunity.
1. How are diseases spread?
Defence Mechanisms
3. How do white blood cells protect
us from disease?
2. How does your body
stop pathogens getting in?
Producing Antibodies
Task 3• Explain how white blood cells work
using combination of sentences and labelled diagrams.
– Key words: Antibodies, antigens, antitoxins,
1. How are diseases spread?
Defence Mechanisms
3. How do white blood cells protect
us from disease?
2.How does your body
stop pathogens getting in?