General Pathology

An Introduction to General Pathology

• The term pathology is derived from:
  • Pathos, or suffering
  • Logos, or reasoning/logic.
• Pathology is defined as the study of disease including:
  • Aetiology - causal factor(s)
  • Pathogenesis - the development of the disease within the body.
  • Lesions - the observable structural changes in the tissues and fluids of the body.
  • Pathophysiology - the functional changes in diseased tissues.
  • Sequel - the consequences of the disease in the body.
  • Remote effects - the effect of disease in one tissue on other tissues in the body.

Lesions

• Lesions are the abnormalities or changes seen in living tissues due to disease.
• Observed in
  • The live animal
  • Tissues surgically removed from the live animal
    • Biopsy/ excision
  • Animals soon after death
    • Necropsy, post-mortem examination.

Decription of Lesions

• Descriptions of lesions is very important
• Whole organs, tissues or individual lesions are described under headings such as
  1. Size
  2. Shape
  3. Colour
  4. Weight
     • Generally in relation to body weight
  5. Texture and Consistency
  6. Appearance of the cut surface
  7. Contents of hollow organs
  8. Position, relationships and effects on adjacent tissues

Disease

Definition and Type

• Disease is a definite morbid (illness producing) process, having a characteristic train of symptoms or signs.
  • May affect the whole body or any of its parts.
  • The disease's aetiology, pathology and prognosis may be known or unknown.
• There are two main categories of disease.
  1. Acute
     • Characterised by sudden onset and short duration.
     • The outcome of acute disease may be:
       • Death
       • Resolution due to host defence response or clinical therapy
       • Progression to chronic disease
  2. Chronic
     • Characterised by insidious onset and protracted course.
     • The outcome of chronic disease may be:
       • Progressive destruction of tissue
         • Compromises funtion and endangers life,
       • The halting of the course of disease, with tissue repair by scarring.