Week%201%20Introduction%20to%20Pathology

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Week 1Introduction to Pathology

• Dr.I.Taci Cangül
• Bursa-2008

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What is Pathology?

• Scientific study of disease" or the alterations
  that occur when abnormal influences (bacteria,
  viruses, etc.) affect cells, tissues, or body
  systems. More specifically, pathology may be
  defined as the "scientific study of the
  molecular, cellular, tissue, or organ system
  response to injurious agents or adverse
  influences."

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Pathology Deals with

• The causes of disease (etiology)
• Mechanisms of disease (pathogenesis)
• Structural alterations of cells and tissues
• Functional alteration and consequences of disease

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Function of Pathology

• Pathology serves as a "bridge" or "link" between
  the preclinical subjects (anatomy, physiology,
  etc.) and the courses in clinical medicine.
  Actually, pathology provides a logical means of
  relating the knowledge of normal structure and
  function (anatomy and physiology) to abnormal
  structure and function as encountered in a
  diseased animal.

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Basic Language of Pathology

• In order for a subject or course to be
  meaningful, one should become familiar with the
  basic terminology applicable to that subject.

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Health

• State in which an individual is living in
  complete harmony with his environment"
• A relative state
• All body functions are performed normally even
  though lesions may be present in organs and/or
  tissues. It should be remembered that the
  transitional zone between health and disease is
  difficult to define

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Disease

• State in which an individual exhibits an
  anatomical, physiological, or biochemical
  deviation from the normal. The term "disease" is
  employed to describe a state in which there is
  sufficient departure from the normal for clinical
  signs or symptoms to be produced. 

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Lesion

• Structural or morphological alterations
  associated with a diseased state in an
  individual
• Gross lesion Naked-eye
• Microscopic lesion Light microscope
• Ultrastructural lesion Electron microscope
• Pathognomonic Lesion A change which is
  specifically characteristic of a disease. When
  one sees a pathognomonic lesion, he knows that a
  particular disease is present. 

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Etiology

• Study of the cause of a disease"
• An etiologic agent is the factor (bacterium,
  virus, etc.) responsible for lesions or a disease
  state.
• Predisposing Causes of Disease Factors which
  make an individual more susceptible to a disease
  (damp weather, poor ventilation, etc.)
• Exciting Causes of Disease Factors which are
  directly responsible for a disease (bacteria,
  viruses, hypoxia, chemical agents, etc.). 

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Clinical Signs

• Functional evidence of disease which can be
  determined objectively or by the observer"
  (lameness, salivation, increased respiratory
  efforts, etc.)
• Clinical signs are seen only in the living
  individual.

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Diagnosis

• Determination of the nature of a disease"
• A morphologic or anatomic diagnosis is based on
  the location and nature of the lesion
  (hemorrhagic enteritis, etc.). Etiologic
  diagnosis is made on the basis of the cause
  (dirofilariasis, etc.). Definitive diagnosis is
  made on the basis of the specific disease entity
  involved (canine distemper, etc.). A clinical
  diagnosis is made on the basis of clinical signs
  observed in the living animal. 

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Prognosis

• Probable outcome of a disease in a living
  individual. It is the clinician's estimate of the
  severity and possible result of a disease. 

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Pathogenesis

• Progressive development (sequence of events) of
  a disease from the time it is initiated to its
  final conclusion in recovery or death 

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• Necropsy Gross examination of the carcass by
  systematic dissection in order to evaluate any
  abnormal changes (lesions) that may be present
• Autopsy Synonymous to necropsy in human medicine
• Biopsy Removal and examination of tissue
  obtained from the living body
• Euthanasia Intentional putting to death of an
  individual with an incurable or painful disease
  by employing humane means

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• Somatic death Death of the entire body
• Necrobiosis Death of cells at the end of their
  normal life-span within the living body
  (epithelial cells of the skin, leukocytes, etc.)
• Necrosis Morphological changes caused by the
  progressive degradative action of enzymes on the
  lethally injured cell within the living body

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Postmortem Changes

• Cell death which accompanies or occurs after
  death of the entire body (somatic death)
• Postmortem autolysis Self-digestion by enzymes
• Postmortem putrefaction Decomposition of tissues
  by bacterial enzymes after death of the entire
  body
• Rigor mortis Stiffening of all muscles after
  death

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Branches of Pathology

• General Pathology
• Systemic Pathology
• Gross Pathology
• Cellular Pathology
• Surgical Pathology
• Clinical Pathology
• Immunopathology