The barriers that keep pathogens out, and how white blood cells destroy the ones that get in.
What you will learn
- Describe how skin, nose, airways, stomach and tears keep pathogens out
- Describe phagocytosis, antibodies and antitoxins
- Explain why antibodies are specific
- Read a primary and secondary response from an antibody graph
Keeping pathogens out
These non-specific defences work against any pathogen:
- skin: a tough barrier
- nose: hairs and mucus trap particles
- trachea and bronchi: mucus traps pathogens and cilia sweep it up to the throat
- stomach: hydrochloric acid kills pathogens in food
- eyes: tears contain lysozyme, an enzyme that breaks down bacteria
The rest of this lesson and its 11 practice questions are locked.
In this lesson
- Keeping pathogens out
- White blood cells
- Meeting a pathogen twice
- Try it: Barriers first
11 practice questions, marked as you go; about 20 minutes in all.
Key terms
Non-specific, Cilia, Antigens, Memory cells, Immune, Vaccination
In this unit: Infection and response
Pathogens and how they spread, the body's defences and the immune system, vaccines, antibiotics and resistance, drug trials, and (Biology only) monoclonal antibodies and plant disease.