Maintaining Healthy Systems

The 10 leading causes of death (WHO, 2008) World Deaths in millions % of deaths Ischaemic heart disease % Stroke and other cerebrovascular disease % Lower respiratory infections % Chronic obstructive pulmonary disease % Diarrhoeal diseases % HIV/AIDS % Trachea, bronchus, lung cancers % Tuberculosis % Diabetes mellitus % Road traffic accidents %

Preventive Health Care  The best way to stay healthy is to prevent disease in the first place.  HOW?

 Eat well.

 Avoid unhealthy foods.

 Exercise.

 Make smart choices.

 Prevent illnesses.

How does your immune system work? # 1 – Your Skin  Skin is a barrier to protect your body against pathogens.  Pathogens are disease-causing agents (e.g. bacteria, viruses, fungi, etc.).  Enzymes in tears, mucous, perspiration and saliva can destroy microbes.

# 2 – In the Respiratory System  Mucous and cilia trap debris and pathogens.

# 3. White blood cells  White blood cells engulf microbes, then destroy them with enzymes.  Some white blood cells produce pus at the site of an infection when they die.

# 4. The Inflammatory Response  Swelling, heat and redness due to increased blood flow to the infected area.  Fever - increased temperature prevents bacteria from reproducing as fast.

# 5. The Immune Response  Pathogens have proteins on their surface called antigens.  Some white blood cells make proteins called antibodies that attach to antigens to help destroy the pathogens.

Allergies Allergic reactions occur when your body recognizes the antigens on allergens as dangerous, and tries to fight them. An overly sensitive immune system recognizes such harmless substances as foreign invaders, and then stimulates the production of antibodies to destroy them. This in turn induces the release of chemicals like histamine, which is responsible for triggering the inflammatory response of the body. The blood vessels are dilated during an allergic reaction so that the white blood cells can get access to the foreign invaders. Immune cells recognize proteins on allergens as dangerous (e.g. proteins on pollen). Antibodies are produced. Histamine is released by cells (causes capillaries to be more permeable) so white blood cells squeeze into extracellular fluid.

Histamine is an immune system mediator or, more simply, a chemical messenger that helps direct your body's response to a foreign invader. Histamine tells your body's natural defense mechanisms how to react to something it perceives as foreign.

A hypersensitive immune system recognizes such harmless substances as foreign invaders, and then stimulates the production of antibodies to destroy them. This in turn induces the release of chemicals like histamine, which is responsible for triggering the inflammatory response of the body. The blood vessels are dilated during an allergic reaction so that the white blood cells can get access to the foreign invaders.

What are vaccines?  antigen-containing substances obtained from weakened or dead microbes Jenner, 1796 smallpox

Pasteur, 1885 rabies

Salk, 1955 polio

What are antibiotics?  chemical agents that are toxic to bacteria Fleming, 1928

 Colds and flu are caused by viruses, so antibiotics are useless against them.

Organ Transplantation  What organs and tissues can be donated?  How many people in Ontario are waiting for organ transplants?  How is living donation different from organ donation after cardiac death (DCD)?