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HUMAN ANATOMY/PHYSIOLOGY Chapter 4 – Mechanisms of Disease

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Page 1: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

HUMAN ANATOMY/PHYSIOLOGY

Chapter 4 – Mechanisms of Disease

Page 2: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

Disease Terminology

Health 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

Page 3: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

Disease Terminology

Etiology 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.

Page 4: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

Disease Terminology

Acute 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

Page 5: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

Patterns of Disease

Epidemiology 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

Page 6: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

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)

Page 7: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

Mechanisms of Disease

Pathophysiology Study of

underlying physiological aspects of disease

Genetic Mechanisms Pathogenic

organisms Tumors and cancer Physical and

chemical agents malnutrition Autoimmunity Inflammation degeneration

Page 8: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

Risk Factors (predisposing conditions)

Genetic factors Age Lifestyle Stress Environmental factors Preexisting conditions

Page 9: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

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

Page 10: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

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

Page 11: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

Pathogenic Organisms

Classifying bacteria (continued) Shape

Rod-shaped (bacilli/bacillus)

Round-shaped (cocci/coccus)

Spiral shaped (spirillum/spirilla)

Page 12: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

Pathogenic Organisms

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

Page 13: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

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)

Page 14: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

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)

Page 15: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

Pathogenic Organisms

Examples of fungal infections: Yeast cells infect

membranes all over the body

Athlete’s foot ringworm

Page 16: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

Pathogenic Organisms

Protozoa One-celled

organisms that have a nucleus

Cause disease by being parasites

Major groups: Amoebas Flagellates Ciliates Sporozoa

Page 17: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

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

Page 18: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

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

Page 19: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

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

Page 20: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

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

Page 21: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

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.

Page 22: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

Pathogenic Organisms

Prevention and control (continued) Transmission by a vector

Can be prevented by reducing the population of vectors and reducing contact with vectors

Page 23: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

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)

Page 24: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in
Page 25: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

Tumors and Cancer

Neoplasm 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

Page 26: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

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

Page 27: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

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

Page 28: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

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)

Page 29: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

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

Page 30: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

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)

Page 31: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

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

Page 32: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

Pathogenesis of Cancer

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

Page 33: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

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

Page 34: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

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

Page 35: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

Inflammatory Response

A number of body responses that attempts to minimize injury to body tissue.

Four primary signs: Redness Heat Swelling Pain

Page 36: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

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

Page 37: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

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

Page 38: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

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.

Page 39: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

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

Page 40: Chapter 4 – Mechanisms of Disease.  Health  Physical, mental, and social well-being—not merely the absence of disease  disease  An abnormality in

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.