Healthteacher

Fighting Infection: How the Body Fights Germs, Part I

Adapted from the National Institute Allergy and Infectious Disease,
National Institutes for Health

Your immune system has an arsenal of ways to fight off invading microbes.  Some of the body's special fighting cells sacrifice their lives to rid you of disease and restore your body to a healthy state. Some of the microbes normally present in your body also help destroy microbial invaders.

 

The body has 3 defenses against infectious invaders:

1.  Natural Barriers: 

a.  Healthy skin.  Skin that is broken into by a cut, an insect bite, a burn or another type of injury is open to infection.

b.  Mucous membranes. These linings of the airways and intestines are coated with secretions that fight microbes.

c.  Airway filters.  The airways are lined with mucous and have tiny hairlike extensions (called cilia) to sweep germs away from the lungs.

d.  Gastro-intestinal (GI) secretions.  The acids, enzymes and other antibacterial secretions of the GI tract help fight infection. Contractions that occur in the GI tract also help move out infection.

e.  Design of the genitourinary (GU) system.  The length of the urethra discourages bacteria from invading the bladder and proceeding upward into the kidneys. The "flushing" as the bladder empties also directs any bacteria down and out of the body.

 

2.  Process of Inflammation:

An injury, including an invasion by bacteria, causes a process called "inflammation" to occur.  Inflammation is the body's defense against a threat to its safety.  The body&'s defenses are directed to the site of the attack.

 

  • Blood supply increases
  • White Blood Cells (WBCs) pass from the blood vessels into the inflamed area (jumping right into the battle zone)
  • The bone marrow releases more WBCs into the blood stream while working to make many more of them to fight off the invasion.

    Did you know?  Air pollutants, such as tobacco smoke, can weaken the body's defense team.

     

    Signs of your body's efforts to fight off an infection include: 

    Fever
    Fever is one of your body's special ways of fighting an infection. Many microbes are very sensitive to temperature changes and cannot survive in temperatures higher than normal body heat, which is usually around 98.6 degrees Fahrenheit. Your body uses fever (above 100 degrees) to destroy flu viruses, for example.

    Coughing and sneezing
    Another piece in your immune system's reaction to invading infection-causing microbes is mucus production. Coughing and sneezing help mucus move those germs out of your body efficiently and quickly.

    Other methods your body may use to fight off an infection include:

  • Inflammation
  • Vomiting
  • Diarrhea
  • Fatigue
  • Cramping

     

    3. Immune response

    Once an infection develops, the immune system produces several substances

    that specifically attack the invading organism.  

  • Antibiodies may be produced that will directly kill the organisms or make it easier for the white blood cells to target and kill them. 
  • Also the immune system may send killer T cells (yet another type of wbc) to specifically attack the invading organism. 

     

    Anti-infective drugs can be prescribed to aid the body's natural immune system.

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