Section 3.3 Maintaining Healthy Systems

The Enemies of our Immune System Pathogens are harmful organisms that can invade the body and cause disease.  Includes viruses, bacteria, parasites, and fungi 1700’s E.g. Smallpox (pox virus)

E.g. Bacteria - Cholera

E.g. Fungi – Athletes Foot (Tinea pedis)

E.g. Parasite – Common roundworm (Ascaris lumbricodois)

Our Body’s Immune System Innate Immune System  1 st immune response (within hours)  Phagocytes in the body attack the parasites at the site of infection.  They recognize pathogens by identifying their antigens and then engulf the parasites.  Antigens are proteins that are located on the surface of a pathogen (each pathogen has a unique antigen)

Adaptive Immune System  2 nd immune response (days to weeks after parasite enters)  The adaptive immune system produces antibodies which will attack the pathogens  They will also form memory cells to protect the body from the same pathogen

Vaccinations – E.g. Virus A vaccine for the flu is composed of antigens from the influenza virus. The body will then produce antibodies that are specific to the influenza virus.  If the flu virus infects an individual after the flu shot, their body will have a stronger immune response  therefore killing the virus.

Vaccine Controversy - Pros If used widespread, the vaccine can eliminate a harmful pathogen  E.g. smallpox virus  E.g. rubella virus (German measles) Vaccines allow the human body to prepare for infection in a manner that is more safe than being exposed to the pathogen without vaccination.

Vaccination Controversy - Cons Vaccines tend to produce side effects. The side effects vary between vaccine but range from:  Redness, swelling, itching, bruising, headache, nausea, severe allergic reactions, tiredness, vomiting, seizure, fevers, coma & brain damage (rare), Vaccines are expensive to produce  The Canadian government spent 2 billion in vaccines against H1N1 Vaccinations can be dangerous for children Vaccines may accelerate the rate of pathogen evolution  Super bugs

The Community Immunity Dilemna If a small percentage of the population receives a vaccination, then the virus (or other pathogen) will be able to survive and harm many people.  All the individuals who took the vaccine were susceptible to the side effects. If a large percentage of the population receives a vaccination, then everyone is protected. Even those that did not receive the vaccination.

Independent Reading – Stopping the Spread of Disease (page ) Read pages Answer questions 5-8 (page 115)

Thursday Work Activity 3-C Read pages Answer all questions on page 120 Include a title page