1. Human Anatomy/Physiology
Chapter 4 – Mechanisms of Disease

2. Disease Terminology Health disease Pathology Pathogenesis
Physical, mental, and social well-being—not merely the absence of disease
disease
An abnormality in body function that threatens health
Pathology
Study of disease
Pathogenesis
The pattern of a disease’s development

3. Disease Terminology Etiology Idiopathic Symptoms Syndrome
the study of the factors that cause a disease
Idiopathic
Refers to a disease with an unknown cause
Symptoms
The objective and subjective abnormalities associated with a disease
Syndrome
Collection of different signs and symptoms, usually with a common cause, that presents a clear picture of a pathological condition.

4. Disease Terminology Acute Chronic Incubation Convalescence Remission
Signs and symptoms appear suddenly, persist for a short time, then disappear
Chronic
Diseases that develop slowly and last for a long time (perhaps for life)
Incubation
Latent (hidden) stage of a disease
Convalescence
recovery
Remission
Reversal of a chronic disease

5. Patterns of Disease Epidemiology Endemic diseases Epidemic Pandemic
Study of occurrence, distribution, and transmission of diseases in human populations
Endemic diseases
Native to a local population
Epidemic
Occurs when a disease affects many people at the same time
Pandemic
Widespread, perhaps global, epidemic

6. Patterns of Disease
Discovering the cause of a disease is difficult because many factors affect disease transmission
Disease can be fought through prevention and therapy (treatment)

7. Mechanisms of Disease Pathophysiology Genetic Mechanisms
Study of underlying physiological aspects of disease
Genetic Mechanisms
Pathogenic organisms
Tumors and cancer
Physical and chemical agents
malnutrition
Autoimmunity
Inflammation
degeneration

8. Risk Factors (predisposing conditions)
Genetic factors
Age
Lifestyle
Stress
Environmental factors
Preexisting conditions

9. Pathogenic Organisms Bacteria
Tiny cells without a nucleus (prokaryotic)
Secretes poisons (toxins) that damage normal cells and tissues
Form colonies in the body that disrupt normal body functions

10. Pathogenic Organisms Classifying Bacteria Oxygen requirements
Aerobic (needs oxygen)
Anaerobic (doesn’t need oxygen)
Staining (how cell wall accepts staining)
Gram positive (accepts stain)
Gram negative (does not accept stain
Certain antibiotics work for certain cell walls

11. Pathogenic Organisms Classifying bacteria (continued) Shape
Rod-shaped (bacilli/bacillus)
Round-shaped (cocci/coccus)
Spiral shaped (spirillum/spirilla)

12. Pathogenic Organisms
Some bacteria produce spores (endospores) that are resistant to chemicals, heat, and dry conditions

13. Pathogenic Organisms
Some bacteria have an ability to change genetically and make themselves resistant to certain antibiotics.
This can make treatment difficult.
MRSA (methicillin resistant Staphylococcus aureus)

14. Pathogenic Organisms Fungi
Simple organisms similar to plants but without chlorophyll
Parasitize tissue on or near skin or mucus membranes
Can be single-celled (yeasts) or multicelled (molds)

15. Pathogenic Organisms Examples of fungal infections:
Yeast cells infect membranes all over the body
Athlete’s foot
ringworm

16. Pathogenic Organisms Protozoa One-celled organisms that have a nucleus
Cause disease by being parasites
Major groups:
Amoebas
Flagellates
Ciliates
Sporozoa

17. Pathogenic Organisms Pathogenic Animals Called Metazoa
Cause disease by acting like a parasite
An organism that spreads disease to other organisms is called a vector

18. Pathogenic Organisms Major groups of pathogenic animals
Nematodes (roundworms)
Transmit disease through foods or biting insects
Platyhelminths (flatwroms)
Tapeworm
Arthropods
Ticks, mites, lice, fleas, stinging bees, wasps, spiders

19. Pathogenic Organisms Virus
Intracellular parasites made of genetic material (DNA or RNA)
Living or nonliving?
Invade cells and inject genetic material
Some symptoms show up immediately and some don’t for many years

20. Pathogenic Organisms Virus (continued) Very small
200 can fit on a period on a typed page
Examples of viral diseases
Polio
AIDS
Cold
Flu
Herpes
rabies

21. Pathogenic Organisms Prevention and Control Mechanisms of transmission
Person-to-person contact
Can be prevented by education
Can be prevented by using aseptic technique (table 4-6)
Environmental contact
Can be prevented by avoiding contact
Can be prevented by safe sanitation practices
Opportunistic invasion
Can be prevented by avoiding changes in skin and mucous membranes
Can be prevented by cleansing of wounds.

22. Pathogenic Organisms Prevention and control (continued)
Transmission by a vector
Can be prevented by reducing the population of vectors and reducing contact with vectors

23. Pathogenic Organisms Prevention and control (continued)
Other prevention and treatment strategies
Vaccination – stimulates immunity
Chemicals – destroy or inhibit pathogens
Antibiotics – natural compounds derived from living organisms (see next page)
Synthetic compounds (examples: ACT and AZT)

25. Tumors and Cancer Neoplasm Types of tumors New matter
An abnormal growth of cells
Also called a tumor
Types of tumors
Benign – remain localized within the tissue where they arose
Malignant – spreads to other regions of the body

26. Tumors and Cancer Benign tumors Tend to stay together
Often surrounded by a capsule of dense tissue
Often well-differentiated
Usually not life threatening unless they interrupt a vital function

27. Tumors and Cancer Causes of Cancer
Hyperplasia – process that produces too many cells
Anaplasia – production of undifferentiated tumor cells
All cancers are caused by a mistake or problem in cell division

28. Tumors and Cancer Factors that can play a role in cancer:
Genetic factors
Oncogenes – abnormal “cancer genes”
Carcinogens – chemicals that affect genetic activity, often causing abnormal cell reproduction
Mutagens – cause changes in DNA structure
Age
Environment
Sunlight causing skin cancer; radiation; asbestos fibers
Viruses
HPV – human papillomavirus (cervical cancer)

29. Tumors and Cancer Malignant tumors No capsule Don’t stay in one place
Cells fall away and start new tumors somewhere else
Metastasis – spreading of abnormal cells

30. Pathogenesis of Cancer
Methods used to detect presence of cancer
Self examinations
Diagnostic imaging
Radiography (x-rays)
Computed Tomography (CT scans)
Magnetic Resonance Imaging (MRI)

31. Pathogenesis of Cancer
Methods of detection (continued)
Biopsy
Removal of some tissue for further tests and examination
Blood Tests
Example: some forms of cancer elevate blood concentration levels of calcium ions
Absence of early detection and/or treatment usually results in an advanced illness followed by death

32. Pathogenesis of Cancer
Many patients suffer from cachexia:
Loss of appetite
Severe weight loss
Physical weakness

33. Pathogenesis of Cancer
Treatment options:
Surgery – removal of cancerous tissue
Chemotherapy – Attacking malignant cells with “cell killing” drugs
Radiation therapy – Use of radiation to destroy cancerous malignant cells

34. Pathogenesis of Cancer
Treatment options (continued)
Laser therapy – Intense beam of light to destroy tumors
Immunotherapy – New treatment that bolsters the body’s own defenses

35. Inflammatory Response
A number of body responses that attempts to minimize injury to body tissue.
Four primary signs:
Redness
Heat
Swelling
Pain

36. Inflammatory Response
Inflammation Mediator (I.M.)
Body chemicals released when tissues undergo damage:
Histamines
Prostaglandins
Kinins
I.M. causes blood vessels to dilate
Increases blood volume to injured area and causes redness and heat

37. Inflammatory Response
I.M. allows white blood cells to travel quickly to injured site
Liquids leaking out of vessels causes swelling or edema
Fluids that accumulate in the inflamed tissue is called inflammatory exudate

38. Inflammatory Response
Chemotaxis
Movement of white blood cells to injured area
Pus
Inflammatory exudate thickens with used white blood cells
Process of inflammatory response eventually eliminates the irritant and healing can begin.

39. Inflammatory Response
Regeneration
Healing and repair of tissue (same cells)
Replacement
Different cells take place of injured cells and results in scarring
Tissue repairs are a combination of regeneration and replacement

40. Inflammatory Response
Sometimes the inflammatory response affects the entire body
Fever – elevated body temperature
Increased body temperature often kills or helps fight off pathogens.
Note: Study diagram on page 97.