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’sE.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 1st 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

2nd 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 112-114)

Read pages 112-114Answer questions 5-8 (page 115)

Thursday Work Activity 3-C

Read pages 119-120Answer all questions on page 120Include a title page