First Line of Defence
Presentation
•
Science
•
9th Grade
•
Easy
Mandy Mills
Used 5+ times
FREE Resource
5 Slides • 11 Questions
1
2
Poll
How are you feeling today?
3
Word Cloud
What is the role of the immune system?
4
The immune system's job is to protect the body from harmful pathogens.
In order to do this, there are three levels of defence.
5
Fill in the Blanks
What does the immune system protect us against?
6
First Line of Defence
The first line of defence is made up of physical and chemical barriers that stop pathogens from entering the body.
It works all of the time and does not need to be 'activated'.
Can you think of any examples? How might your body stop you from getting sick?
7
Draw this table in your books
Type | Mechanism | How it stops pathogens |
|---|---|---|
| Skin | |
| Mucus / Cilia | |
| Reflexes | |
| Stomach Acid | |
| Tears / Saliva | |
| Sweat / Oils | |
| Mucus | |
8
Match
Match each barrier to its correct function:
Skin
Cilia
Stomach Acid
Tears
Mucus
A tough, waterproof layer
Tiny hairs that push out trapped germs
Contains acid that kills most bacteria
Has enzymes that breaks cell membranes
Traps germs and has enzymes to kill them
A tough, waterproof layer
Tiny hairs that push out trapped germs
Contains acid that kills most bacteria
Has enzymes that breaks cell membranes
Traps germs and has enzymes to kill them
9
Our bodies have harmless (good) bacteria that help defend against pathogens.
Good bacteria help by:
Good Bacteria
Take up space so the bad bacteria have no room to grow
Make chemicals that kill the bacteria
Break down food and give energy to the rest of our immune system
10
Multiple Choice
Which of the following is NOT part of the first line of defence?
Skin
Stomach Acid
White Blood Cells
Tears
11
Multiple Choice
How does stomach acid help protect the body?
It traps bacteria like mucus
It washes bacteria away from the skin
It kills bacteria that enter through food
It produces antibodies
12
Fill in the Blanks
The tiny hair-like structures in the airways that move mucus upwards are called
13
Categorize
Skin
Cilia
Tears
Stomach Acid
Good Bacteria
Sort the following defences into physical, chemical, or biological barriers:
14
Reorder
Reorder the steps to show how mucus and cilia protect the lungs:
Mucus traps dust, bacteria, and viruses
Cilia move mucus upwards towards the throat
Mucus is swallowed or coughed out
15
Multiple Choice
True or False: Good bacteria in the gut harm the immune system.
True
False
16
Multiple Choice
True or False: The first line of defence includes white blood cells.
True
False
Show answer
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