Bodily Defenses Image Map

Hazards for the liver include certain infections and certain chemicals that are toxic to liver cells. Hazards for the kidney include certain heavy metals.  We discuss them separately because the hazards have different mechanisms of action.


Hepatitis is irritation (inflammation) of liver. (The word ending "itis" means inflammation.) However, many causes of hepatitis go beyond inflammation and end in death of liver cells and eventual replacement with scar tissue (called "cirrhosis" of the liver).

Causes of hepatitis range from alcohol to viruses.  Hepatitis can even be caused by our own immune system.  This occurs when a genetically defective immune system begins to attack liver cells after the immune system is activated, usually by a virus.

The breakdown of alcohol causes the release of many chemicals that are toxic to the liver.  A build up of these chemicals will cause hepatitis.  After a long history of alcohol abuse, people will develop cirrhosis of the liver. See more on alcohol here.

Certain viral infections can also cause hepatitis. There are six different hepatitis viruses:

  • hepatitis A - vaccine available. Spread by feces of infected person (contaminated food or water)
  • hepatitis B - vaccine available. Spread by blood (transfusions, contaminated needles, etc.) and blood fluids (sex, shared toothbrushes) from infected person.
  • hepatitis C -  no vaccine available. Spread by blood and body fluids of infected person. The leading reason for liver transplants. 
  • hepatitis D - no vaccine available.  Spread by blood and blood fluids from infected person.  Only occurs in the presence of a hepatitis B infection.
  • hepatitis E - no vaccine available.  Spread by feces of infected person.

Knowing how these viruses are spread should help you know what you need to do to prevent infection.

For more information see the Communicable Disease Center Web site.


Introduction | Why It Matters | How We Find Out | What We Know | Story Time
Common Hazards | Activities | Self-Study Game | Teachers Pages | Standards (TEKS)

Peer Curriculum | Organ Systems Home Page | Communication Exercises
Copyright 2001-2003
Web Site Privacy Statement