Body Defence

 

4.2

 Body Defence

 

Non-specific body defence mechanism Specific body defence mechanism

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

 

Passive Immunity and Active Immunity

 

Passive Immunity
Natural  Artificial
  • 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

 

Active Immunity
Natural  Artificial
  • 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

 

Immune System

Causes that weaken the immune system Practices that strengthen the immune system
  • Exposure to polluted air
  • Stress
  • Exposure to pesticides
  • Getting enough sleep or rest
  • Exercising and inhaling fresh air
  • Doing periodic health examination

Body Defence

 

4.2

 Body Defence

 

Non-specific body defence mechanism Specific body defence mechanism

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

 

Passive Immunity and Active Immunity

 

Passive Immunity
Natural  Artificial
  • 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

 

Active Immunity
Natural  Artificial
  • 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

 

Immune System

Causes that weaken the immune system Practices that strengthen the immune system
  • Exposure to polluted air
  • Stress
  • Exposure to pesticides
  • Getting enough sleep or rest
  • Exercising and inhaling fresh air
  • Doing periodic health examination