Pathogens and defences
Introduced| English | Meaning |
|---|---|
| pathogens/ˈpæθədʒnz/ | Disease-causing agents, such as certain bacteria, viruses, fungi or parasites. |
| infectious/ɪnˈfekʃəs/ | infectious |
| vectors/ˈvektəz/ | vectors |
| mucus/ˈmjuːkəs/ | A slippery secretion that protects and lubricates surfaces and can trap particles and pathogens. |
| cilia/ˈsɪlɪə/ | Small hair-like structures on cells that can beat to move the cell or nearby material. |
The enemy at the gates
- The world is full of microbes that can make you ill. Your body is under constant attack.
- Disease-causing microbes are pathogens 病原体 — and your body has defences against them.
Pathogen defence route
Follow how the body blocks, detects and removes pathogens.
A pathogen is:
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Pathogens are disease-causing microbes.
Which can be pathogens? (Select all that apply.)
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Bacteria, viruses, fungi and protoctists can cause disease; red blood cells cannot.
Types of pathogen
- Bacteria, viruses, fungi and protoctists can all cause disease.
- A disease that spreads from person to person is infectious 传染性的 (communicable).
The body keeps pathogens out with several defences before white blood cells deal with the rest
An antibody has a shape complementary to one antigen, so it fits only that pathogen
A pathogen spread by coughs and sneezes travels through the:
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Airborne droplets carry pathogens.
How pathogens spread
- Through the air (coughs, sneezes), water and food, contact, and animals/insects (vectors 传播媒介).
- Good hygiene, clean water and sanitation reduce spread.
A white blood cell (green) engulfing round bacteria (purple), a key body defence
Which is a physical barrier to pathogens?
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The skin physically blocks pathogens.
Swallowed pathogens are killed by the ______ in the stomach.
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Stomach acid destroys many pathogens in food.
The body's barriers
- The skin is a physical barrier; the stomach acid kills swallowed pathogens.
- Mucus 黏液 and tiny hairs (cilia 纤毛) trap and remove pathogens in the airways.
Not all microbes are pathogens. Most bacteria are harmless or even helpful (like those in your gut). Only a small minority are pathogens that cause disease.
A mosquito can spread pathogens when it bites
You've got it
- pathogens (bacteria, viruses, fungi, protoctists) cause infectious disease
- they spread by air, water, food, contact and vectors
- the body's first defences: skin, stomach acid, mucus and cilia