The human body is equipped with an incredible natural defence system designed to protect us from disease-producing germs. Every day, we encounter countless microorganisms—yet only a few succeed in causing illness. This powerful protection comes from our immune system, a complex network of physical barriers, white blood cells, and antibodies working together to keep us healthy.
Why Your Immune System Is Your Body’s Best Defence
Our body has many built-in protective mechanisms acting as the first line of defence against harmful germs. These include:
- Skin – a strong protective barrier
- Tears & Saliva – containing enzymes to kill microbes
- Nasal Secretions – filtering pathogens
- Digestive Juices – destroying germs in food
- Lymphoid Tissues – producing immune cells
Every entry point in the body is well-guarded, reducing infection risk significantly.
How Does the Body’s Defence Mechanism Work?
Once disease-causing germs enter the body, the defence system activates instantly.
White Blood Cells: The Soldiers of Your Immune Army
White blood corpuscles (leucocytes) are the body’s emergency responders. They:
- Change shape
- Leave blood vessels
- Move into infected tissues
- Swallow and destroy invading germs
This process prevents the spread of infection.
For instance, during an appendix infection, WBC count increases rapidly, surrounding and sealing off the infection.
How Your Body Recognises and Destroys Germs
How Are Antibodies Formed?
Germs carry chemical substances called antigens. When they enter the body, they trigger the immune system to produce antibodies, which:
- Identify
- Attack
- Neutralize the germs
These antibodies remain in the body, offering future protection.
How Nutrition Strengthens Your Immune System
The ability to produce antibodies depends on the person’s overall health and nutritional status.
Immunity is strongly enhanced by:
- Proteins
- Vitamins
- Protective foods
Individuals who are:
- Undernourished
- Physically or mentally exhausted
- In poor general health
have a weakened ability to fight infections. This lowered resistance is called susceptibility.
What Is Immunity?
Immunity is the body’s natural ability to resist infections. Although germs are present everywhere, diseases occur only when germs multiply in large numbers or immunity is low.
If a group of people is exposed to the same infection, some get sick while others remain healthy. Those who stay healthy are said to be immune.
Types of Immunity
Immunity is classified into two main types:
- Natural (Inborn) Immunity
- Acquired Immunity
Understanding Natural (Inborn) Immunity
Natural immunity is the defence the body possesses without any previous infection or vaccination. It may be:
- Present from birth
- Developed naturally during growth
Species Immunity Examples
- Hens do not suffer from tetanus
- Dogs, rats, and mice do not contract tuberculosis
This is known as species immunity.
Acquired Immunity: Protection Developed Over Time
Active Acquired Immunity
This type of immunity develops when the body produces its own antibodies through:
1. Previous infection
Example: A previous attack of smallpox provides lifelong immunity.
2. Repeated mild exposure
Repeated contact with germs may build resistance.
3. Vaccination
Inoculation with killed or weakened germs stimulates antibody production without causing disease.
This is known as artificial acquired immunity.
Natural Acquired Immunity
Gained after recovering from infections like smallpox.
Passive Acquired Immunity
This occurs when antibodies are received from an external source, such as:
- Antibodies passed from mother to baby
- Medical injections of ready-made antibodies
Protection is immediate but temporary.
How to Support Your Immune System Daily
To maintain strong immunity:
- Eat nutrient-rich foods
- Get sufficient protein and vitamins
- Stay hydrated
- Reduce stress
- Sleep adequately
- Stay physically active
A resilient immune system not only prevents infections but also enhances your overall wellbeing.