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."
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.
It explores and explains the development of basic pathologic mechanisms:
Introduction to pathology
Inflammation, repair and regeneration,
Cell injury, degenerations and infiltrations
Haemodynamic (circulatory) disorders.
Growth disorders and neoplasia.
Mechanisms of Cell Injury
Depletion of ATP
- loss of RNA (basophilia)
- denatured cytoplasmic protein
– large, whorled phospholipid mass (phospholipid precipitate)
Reversible cell injury with cytoplasmic & organelle swelling, blebbing & ribosome detachment
Irreversible cell injury with rupture of membrane & organelles, & nuclear pyknosis
– protein denatured
– proteolysis inhibited
A, Normal myocardium.
B, Myocardium with coagulation necrosis
:focal bacterial (or fungal) infections
– accumulation of inflammatory
:hypoxic death of cells within CNS
A, Kidney infarct exhibiting coagulative necrosis
B, A focus of liquefactive necrosis in the kidney
:microscopic – granulomatous inflammation
Loss of ATP Irreversible mitochondrial damage
Phospholipid breakdown Massive peroxidation due todue to PLPase activation uncontrolled chain reaction
Depolymerization of actin Cleavage of CSK proteins by proteases
Increase in ROS Uncontrolled ROS; inflammation
Release of calcium from Uncontrolled calcium influx
Altered metabolism Loss of amino acids
outline of the dead cells is maintained and the tissue is somewhat firm. Example: myocardial infarction
form of coagulative necrosis (cheese- like)
Example: tuberculosis lesions
enzymatic digestion of fat
example: necrosis of fat by pancreatic enzymes.
Necrosis (secondary to ischemia) usually with superimposed infection
example: necrosis of distal limbs, usually foot and toes in diabetes