DHY 207

Basic Pathology

Concepts of the Pathologic Process

• Pathology- study of disease or abnormal conditions resulting from disease, trauma, defects, genetic abnormalities, etc.

• Etiology- Cause, can be single entity or event or multiple causes

• Susceptibility- Conditions within or around the organism or host do not inhibit the action of pathogenic agents but instead leave the host more likely to be affected

• Resistance- Natural ability of an organism to remain unaffected by pathogenic or toxic agents

• Pathogenesis- How the disease/condition develops, the sequence of events through the progression of the disease or condition

• Manifestations- Visible and invisible observations that the disease or condition is present. This begins on a cellular level

Etiology

• Extrinsic

• Intrinsic

• Psychogenic

• Idiopathic

• Multifactorial

Etiology: Extrinsic

• Microorganisms

• Bacteria

• Fungi

• Viruses

• Physical agents

• Temperature

• Electricity

• Ionizing radiation

• UV radiation

• Ultrasound

• Microwaves

• Lasers

• Chemical agents

• Poison

• Acid

• Venom

• Drugs

• Lead

• Mercury

• Mechanical agents

• Knives

• Guns

• Motor vehicle accidents

• Bad luck

• Nutritional deficiencies

• Scurvy

• Rickets

• Excess obesity

• Iatrogenic

• Infective endocarditis

• Hospital infections

Etiology: Intrinsic

• Genetic

• Sickle cell disease

• Cystic fibrosis

• Some breast cancers

• Immunologic

• Autoimmune

• Lupus

• Rheumatoid arthritis

• Hypersensitivity

• Allergies

• Degenerative

• Osteoporosis

• Osteoarthritis

Etiology: Psychogenic

• Conscious or subconscious reactions or attitudes

• Posttraumatic stress disorder

Etiology: Idiopathic

• Unknown

• Fibromyalgia

Etiology: Multifactorial

• More than one causative factor

• Primary hypertension

• Most cancers

Risk Factors

• Genetic

• Immune system dysfunction

• Compromised first-line defenses

• Skin, exocrine

• Age

• Lifestyle

• Stress

• short/long term

• Environment

• Pre-existing conditions

• Multiple risk factors

Pathogenesis

• The sequence of events during which cells or tissues respond to a specific etiologic agent

• Terminology

• Incubation period, latent period

• Sign, symptom, manifestation, complication

• Exacerbation, resolution, sequela, relapse

• Morbidity, mortality

• Prognosis

Disease Manifestations

• Begin on a cellular level

• Cellular adaptation

• Cellular injury

• Cellular death

Cellular Adaptations

• Adaptive cellular changes occur often and for both normal and abnormal or pathologic reasons

• Resolution or return to normal

• Continued injury

• Cell death

• Atrophy: Abnormal decrease in the number of cells in an organ or tissue

• Hypertrophy: An enlargement of a tissue or organ resulting from an increase in the size of its individual cells but not in the number of cells

• Hyperplasia: An enlargement of a tissue or organ resulting from an increase in the number of cells; the result of increased cell division

• Metaplasia: The transformation of one differentiated cell type to another differentiated cell type. The change from one type of cell to another may be part of a normal maturation process, or caused by some sort of abnormal stimulus

• Dysplasia: Disorder growth; alteration in size, shape, and organization of adult cells. A premalignant condition of the oral cavity

Reversible Cellular Injury

• Free radical injury

• Hypoxic cell injury

• Intracellular imbalance of calcium

Irreversible Injury

• Apoptosis: The programmed cell death as part of an organism’s growth or development.  The cell follows a set of instructions that tell them how to die. These instructions allow the cell to die without causing inflammation or damaging any of the healthy cells around it. Apopsis is a process that allows the body to remove old and damaged cells. It is very common in developing embryos

• Necrosis: The pathologic death of one or more cells, or part of tissue, or an organ that results from irreversible damage to cells. It is a uncontrolled type of cell death that happens before the end of the natural lifespan of the cell

• Caseous necrosis: Unique form of cell death in which the tissue maintains a cheese-like appearance

• Coagulative necrosis: Type of necrosis caused by ischemia (sudden cessation of blood flow) or infarction (obstruction of blood supply to an organ or region of tissue causing local death of the tissue

• Liquefactive necrosis: Type of necrosis which results in a transformation of

the tissue into a liquid viscous mass