Chapter 40-1 Notes

The Immune System


Agents of Disease:


Pathogens: Disease causing agents

Examples: bacteria, viruses, and fungi


Virus: Tiny Particles that invade and replicate within living cells.


    viruses attach to the surface of the cell

    insert their genetic material in the form of RNA or DNA into the host cell

    Replicate within the host cell

    Take over the functions of the host cell


Examples: HIV, Avian Flu, the Flu, Colds, Herpes, HPV, Chicken Pox, Small Pox, Measles, Mumps, West Nile, Malaria, Rabies, Hantavirus, Lyme disease


Bacteria: Single celled Prokaryotes.  Most are harmless but some cause serious disease.


Two Mechanisms:

1.                       Break down the tissues of the infected organism for food

2.                       Release toxins that harm the body


Examples: Streptococcus, diphtheria, botulism, anthrax, gonorrhea, syphilis, Chlamydia


How Disease is Spread:


1.                       Some infectious diseases are spread from one person to another through coughing, sneezing, or physical contact.

    The air acts to carry the thousands of droplets released.

    Pathogens can settle on objects and you can get them by touching them.

    It is important to wash your hands often with soap and water.  Cover your mouth when sneezing or coughing.

2.                       Some pathogens are spread through contaminated water or food.

    Partially or uncooked meat can spread disease.

    Food sitting out too long.

    Food prep people not washing their hands after using the bathroom.

    Contaminated water caused by poor sanitation and untreated sewage.

3.                       Some pathogens are spread by infected animals.

    Mosquitoes, ticks, wild animals and mice are often carriers of viruses

4.                       Some are spread through the exchange of bodily fluids.

    HIV is caused by the exchange of blood or semen.


Fighting Infectious Disease


Antibiotics: Compounds that kill bacteria without harming the cells of the human or animal hosts. 


    Antibiotics work by interfering with the cellular processes of microorganisms.

    Antibiotics do not work on viruses.

    It is important not to take antibiotics unless you are really sick with a bacterial infection because this causes the bacteria to mutate and change into something we do not have an antibiotic for.

    Viruses either have to run their course; drink water and rest.

    Some viruses have vaccines made from dead viruses.  Some viruses do not have vaccines and will cause death. Vaccines must be given BEFORE you get the virus.