1. Disturbances to homeostasis and the body’s responses
Mechanisms of Disease
Disturbances to homeostasis and the body’s responses

2. Disease Mechanisms Genetic mutations
Pathogenic organisms and particles
parasites
Tumors and cancer
Physical and chemical agents
Malnutrition
Autoimmunity
Inflammation
Degeneration

3. Risk Factors Genetic factors Age Lifestyle Stress
Environmental factors
Preexisting conditions
Many risk factors overlap and can be avoided.

4. Pathogenic particles Viruses – small,nonliving particle,
capsid and nucleic acid
can not reproduce on own
Symptoms can be slow to appear
Ex. SARS, West Nile, HIV (table 5-1)
Prion – pathogenic protein molecule, convert normal proteins to abnormal ex. Mad cow

5. Bacteria- Pathogenic organism
Prokaryotic
Produce disease by:
secreting toxins
parasitic in human cells
form colonies to disrupt normal function
Classified by
Function: aerobic/anaerobic
Staining properties: gram -, gram +
Size and shape – coccus, spirilla, bacillus
Table 5-2 for examples
Spores – formed under adverse conditions

6. Fungus Fungus Heterotrophic, parasitic Molds, mildew
Often resists treatment
Ex. Athelete’s foot, yeast infections (table 5-3)

7. Protozoa Unicellular, eukaryotic organisms Larger than bacteria
Major groups (classified by locomotion)
Amoebas
Flagellates
Ciliates
Sporozoa (usually 2 hosts and 2 life cycles)
Table 5-4 for examples

8. Pathogenic Animals - metazoa
Large, multicellular
Major groups
Nematodes – roundworms, human tissue
Platyhelminths – flatworms and flukes
Arthropods – mites, ticks, lice and fleas, wasps, mosquitoes, spiders
Table 5-5 for examples