1. DISEASE AS A FAILURE OF HOMEOSTASIS

2. Disease Any condition that prevents the body from working as it should
As a result the body may fail to maintain homeostasis.
Disease may result from pathogens, abnormal cells, carcinogens, poor nutrition, inherited disorder, or risky personal behavior

3. Causes of disease
Inherited disorders – Like down syndrome, cystic fibrosis, sickle cell anemia
Exposure to toxins/ carcinogens – lead poisoning, radiation poisoning
Poor nutrition – scurvy (vitamin C deficiency), goiter (iodine deficiency)
Organ Malfunction – Heart Attack, diabetes
High risk behaviors – lung cancer, drug addiction, skin cancer

4. Pathogens
Virus – particles composed of nucleic acid and protein. They reproduce when they invade living cells
Bacteria – are one celled organisms
Fungus – can be uni or multi cellular. Include yeasts and molds. They eat by absorbing organic substances.
Parasites – can be uni or multi cellular. Survive and by living and feeding on other organisms.

5. Keeping Pathogens Out Skin Protective barrier Sweat, tears, saliva
Contains enzymes to destroy the cell membranes of certain bacteria
Mucous membranes
These line internal membranes that entrap pathogens that are then washed away or destroyed by chemicals.

6. Second line of defense
Leukocytes – Phagocytes for short minor invasions and lymphocytes are for longer more serious invasions
Phagocytes rapidly trap, consume and completely destroy foreign material
The inflammatory response –
Damaged cells release histamine
causes swelling, redness, warmth, and pain in the areas of infection. The damaged cells release certain chemicals which increase blood flow to the area.

7. Macrophages are white blood cells that can ingest large numbers of bacteria
Pus is dead cells, phagocytes, bacteria, and body fluid.
When the pathogen is a virus, the infected cells produce a protein (interferon) that causes nearby uninfected cells to produces enzymes that block reproduction of the virus.

8. Third line of Defense
When the inflammatory response defense in insufficient the pathogen is targeted for destruction by the body’s last line – IMMUNE RESPONSE
It “remembers” each kind of pathogen that enters the body by producing antibodies.
The immune system discriminates between different kinds of pathogens unlike the phagocytes

9. When an antigen is first introduced into your body your system undergoes a primary immune response. The first 5 days or so there is no detectable antibodies or specialized immune cells. It takes about 10 – 15 days to get a gradual increase in these cells
Any other time that the antigen is introduced into your system, it undergoes a more rapid secondary immune response. Within the first day or so high levels of antibodies and specialized immune cells are detected.

10. Type of Immunity
Active Immunity – This is when the body produces its own antibodies to attack a particular antigen
This is when you get a disease and make your own antibodies
Some vaccinations
Therefore – memory cells stay within your body so you can respond to a pathogen quickly during subsequent exposure.

11. Vaccinations Vaccination are of two types –
Uses dead or weakened pathogens (uses chemicals or heat) to destroy the pathogen.
The inactive pathogen enters the blood stream – your immune system attacks it and makes antibodies against it – WITHOUT getting sick – but you MADE the antibodies ---therefore active immunity
OR The vaccine (if pathogen is too dangerous) can be the antibodies instead --- therefore passive immunity

12. Passive Immunity – You are given antibodies from either another person or animal
Vaccinations needing boosters
Through maternal immunity (mother passes antibodies through placenta to unborn child
Through mothers milk
* Passive immunity is only TEMPORARY and lasts only about a month or so because the body destroys the borrowed antibodies.

13. Some Diseases Transplants Allergies Leukemia HIV/ AIDS
Takes immune suppressor drugs.
Allergies
Body makes the wrong antibodies
Leukemia
Making many white blood cells that don’t work
HIV/ AIDS
HIV is a VIRUS that kills helper T cells (the tattle tale cells that let your body know you are sick). Therefore you can die from getting a cold when it has become full blown AIDS

14. Biological Research of disease
Control vs experimental groups
Diagnosing Disease
Preventing and controlling disease
Treating and curing disease