Human Anatomy/Physiology Chapter 4 – Mechanisms of Disease

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

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.

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

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

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)

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

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

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

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

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

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

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)

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)

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

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

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

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

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

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