Fighting Diseases

Fighting Diseases

How Does the Body Defend Against Disease?

The body has two lines of defence against pathogens:

1️⃣ Non-Specific Defences – Stop pathogens from entering.
2️⃣ Immune System (Specific Defences) – Fights pathogens that enter the body.

💡 Key Concept: The body’s immune system recognises and destroys pathogens before they cause harm.

1️⃣ Non-Specific Defences (First Line of Defence)

Barrier

How It Protects

Skin

Acts as a physical barrier to pathogens.

Nose Hairs & Mucus

Traps dust and microbes before they enter the lungs.

Trachea & Bronchi

Have cilia (tiny hairs) that waft mucus up to be swallowed.

Stomach Acid

Kills bacteria in food.

💡 Why Is This Important? These barriers prevent most pathogens from entering the body.

2️⃣ The Immune System (Second Line of Defence)

If pathogens enter the body, white blood cells (WBCs) fight them using three methods:

Method

How It Works

Phagocytosis 🛡️

White blood cells engulf and digest pathogens.

Antibody Production 🏹

White blood cells produce antibodies that bind to antigens on pathogens.

Antitoxins 🧪

Neutralise toxins released by bacteria.

💡 Key Fact: Once the immune system has made antibodies for a pathogen, it remembers them, giving immunity.

How Vaccinations Help Fight Disease

Vaccines contain a weakened or dead form of a pathogen. This stimulates white blood cells to produce antibodies, so the body can fight the real infection in the future.

✔ Prepares the immune system for future infections.
✔ Prevents outbreaks by reducing disease spread.
✔ Herd immunity protects those who cannot be vaccinated.

💡 Example: The MMR vaccine protects against Measles, Mumps, and Rubella.

Questions 

  1. Name two non-specific defences against pathogens.
  2. What are the three ways white blood cells fight pathogens?
  3. How do antibodies help fight infection?
  4. What is phagocytosis?
  5. Why do vaccines prevent disease?

Summary 

  • The body prevents infection using physical barriers (skin, mucus, stomach acid).
  • White blood cells fight infection by engulfing pathogens, producing antibodies, and releasing antitoxins.
  • Vaccines train the immune system to fight infections before they happen.