4.2

 Body Defence

First Line of Defence

Skin - Prevents pathogens from entering the body

Second Line of Defence

White blood cell - Fight pathogens through phagocytosis

Third Line of Defence

Body immune system - Fights pathogens by producing antibodies

• Obtained when a baby receives antibody from breast milk or from mother's blood that flows across the placenta
•  The immunity is temporary and short-lived

• Obtained when an antiserum is injected into the patient's body
• The antiserum fights against pathogens
• The immunity is fast and temporary

• Occurs when a person recovers from an infection
• The immunity lasts long after the infection

• Occurs when a vaccine that contains a dead or weakened pathogen is injected into the body and the immune system responds by producing antibodies
• The immunity lasts long after the infection

• Exposure to polluted air
• Stress
• Exposure to pesticides

• Getting enough sleep or rest
• Exercising and inhaling fresh air
• Doing periodic health examination