Pathology Principles

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Pathology Principles
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General Terminology

• Pathology
• The study of the disease process
• Etiology
• The study of the cause of a disease (often used
  as the actual cause of the disease)
• Disease
• Any abnormal change in the function or structure
  within the body
• Idiopathic Cause of disease is unknown
• Iatrogenic Adverse reactions resulting from the
  treatment by a health professional
• Nosocomial Disease that is acquired while the
  patient is in the hospital

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General Terminology

• Pathogenesis
• The sequence of events that renders the disease
  apparent
• Diagnosis
• The determination of the disease an individual is
  believed to have
• Prognosis
• The predicted course of a disease and the
  prospects for the patients recovery

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General Terminology

• Manifestations
• Observed changes in the patient that are caused
  by the disease (signs, symptoms, and syndromes)
• History
• Written description of symptoms in a patients
  record

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General Terminology

• Symptom
• The patients perception of the disease
  (headache, stomach pain, etc.)
• Sign
• Objective manifestations that are physically
  observed by the health examiner (rash, abnormal
  pulse rate, etc)
• Syndrome
• A cluster of findings that characterize a
  specific abnormal disturbance

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General Terminology

• Frequency
• The rate of occurrence of a pathologic process
  over a given period of time
• Incidence
• The number of newly diagnosed cases of a disease
  in 1 year
• Prevalence
• The number of people who have any given disease
  at any given point in time

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General Terminology

• Morbidity Rate
• The ratio of sick to well persons in a given area
• Mortality Rate
• The ratio of actual deaths to expected deaths

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Inflammation

• The initial bodily response to local injury
• 3 types of injury
• Physical Trauma
• Chemical
• Microbiologic Infections

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Injury

• Acute injury
• Sudden onset and is severe although short lived
• Chronic injury
• A recurring injury such as a shoulder that
  dislocates repeatedly

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Inflammation consist of 4 events

• Alterations in blood flow and vascular
  permeability
• Migration of circulating white blood cells to the
  interstitium of the injured tissue
• Phagocytosis and enzymatic digestion of dead
  cells and tissue elements
• Repair of injury by regeneration of normal cells
  and eventual scar formation.

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Bodys response to injury (REPAIR)

• 1. Hyperemia
• Dilation of arterioles, capillaries and venules
  leading to an increase in blood flow to the
  injury site
• 2. Permeability
• A passage of protein rich plasma across vessel
  walls into the interstitum

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Bodys response to injury (REPAIR)

• 3. Exudate
• A protein rich waste product causes swelling
  which puts pressure on nerve endings and causes
  pain. (Transudate low protein fluid such as
  pulmonary edema)
• 4. Phagocytosis
• Occurs early in the inflammatory response,
  Leukocyte (white blood cells) enzymatically
  digest infecting organisms and cellular debris.

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Bodys response to injury (REPAIR)

• 5. The removal of debris allows a repair or
  regeneration to occur by Granular Tissue ( a
  collagen connective tissue) and eventually scar
  formation.

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Terminology related to repair

• Fibrous adhesions excessive granular tissue in
  the abdomen
• Keloid excessive collagen that produces a
  protruding tumor like scar
• Pus thick yellow fluid
• Supprative an infection caused by bacterial
  organisms which produce toxins that damage
  tissues and cause pus
• Abscess a localized infection that is usually
  beneath the skin or in a solid organ.

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Edema

• The accumulation of abnormal amounts of fluid in
  the intercellular tissue spaces or body cavities.
• Can be localized, as in inflammatory reaction
• Can be generalized (most frequent)

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Ischemia

• Refers to interference with the blood supply to
  an organ or part of an organ that deprives its
  cells and tissues of oxygen.

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Infarct

• A localized area of ischemic necrosis (death)
  within a tissue or organ produced by occlusion of
  either its arterial supply or its venous
  drainage.
• 2 types of Infarction
• Myocardial
• Pulmonary

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Altered Tissue Growth

• Atrophy
• A reduction in size or number of cells
• Hyperplasia
• An exaggerated response to various stimuli in the
  form of an increase in the number of cells in the
  tissue
• Hypertrophy
• An increase in cell size
• Metaplasia
• When normal cells become abnormal

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Neoplasms

• (New Growth) Refers to abnormal proliferation of
  cells that are no longer controlled by factors
  that govern the growth of normal cells.
• Commonly referred to as tumors
• The study of neoplasms is called oncology

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Categories of neoplasms

• Benign
• Tumors closely resemble their cells of origin in
  structure and function
• Malignant
• Neoplasms that invade and destroy adjacent
  structures and spread to distant sites
  (metastasize)
• Commonly called cancers

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Malignant neoplasms spread to distant sites by
one of three pathways

• Seeding within the body cavities
• Lymphatic spread
• Hematogenous spread

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Severity of malignant tumors is determined by
grading and staging

• Grading
• Assesses its aggressiveness or degree of
  malignancy
• Staging
• Extensiveness of a tumor at its primary site and
  the presence or absence of metastasis to lymph
  nodes and distant organs

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Genetic and Developmental Diseases

• Congenital
• Deformities extending from birth
• Hereditary
• Diseases result from developmental disorders
  genetically transmitted from either parent to
  child.

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Hereditary Diseases Radiographic Manifestations

• Downs Syndrome (Mongolism)
• Caused by the presence of an extra chromosome
• Skeletal Abnormalities Include
• Shortening of the middle phalanx of 5th digit
• Squaring of the vertebral bodies
• Hypoplasia of the nasal sinuses
• Delayed closure of cranial sutures

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Hereditary Diseases Radiographic Manifestations

• Marfans Syndrome
• Inherited generalized disorder of connective
  tissue with ocular, skeletal, and cardiovascular
  manifestations.
• Radiographic abnormality is elongation and
  thinning of tubular bones.

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The End