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

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.

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

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)

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

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

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

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)

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

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)

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

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

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

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

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

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

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

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.

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

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.