nani

• Pathology

  Study of the structural, biochemical, and functional changes in cells, tissues, and organs that underlie disease
• Aspects of a disease process that form the core of cellular responses to injury

  • Nature of injurious stimulus
  • Cellular response
  • Pathology
  • Clinical manifestations
• General pathology


  Common reactions of cells and tissues to injurious stimuli
• Systemic pathology


  Alterations and underlying mechanisms in organ specific diseases
• Nature of injurious stimulus

  • Altered physiologic stimuli
  • Reduced oxygen supply
  • Chemical injury
  • Microbial infection
• Cellular response


  • Cellular adaptations
  • Cell injury
  • Cell death
• Pathology


  • 1. Cause or etiology
  • 2. Pathogenesis
  • 3. Morphologic changes
  • 4. Clinical manifestations
• Homeostasis


  Steady state
• Adaptations


  Reversible functional and structural responses to changes in physiologic states and some pathologic stimuli, during which new but altered steady states are achieved, allowing the cell to survive and continue to function
• Hypertrophy


  • Increase in the size of cells
  • Increase in the size of the affected organ
  • No new cells, just larger cells
• Physiologic hypertrophy


  Increased functional demand or stimulation by hormones and growth factors
• Physiologic hypertrophy


  • Uterine hypertrophy during pregnancy
  • Bulging muscles of bodybuilders
  • Cardiac hypertrophy
• Hyperplasia


  • Increase in the number of cells in an organ or tissue in response to a stimulus
  • Dividing cells only
• Physiologic hyperplasia


  Action of hormones or growth factors
• Physiologic hyperplasia


  • Hormonal hyperplasia of breast epithelium
  • Compensatory hyperplasia of liver after partial hepatectomy
  • Hyperplasia of bone marrow in response to blood cell deficiency
• Pathologic hyperplasia


  Excessive or inappropriate actions of hormones or growth factors acting on target cell
• Pathologic hyperplasia


  • Endometrial hyperplasia
  • Benign prostatic hyperplasia
• Atrophy


  Reduction in the size of an organ or tissue due to a decrease in cell size and number
• Causes of pathologic atrophy

  • Loss of endocrine stimulation
  • Loss of innervation
  • Diminished blood supply
  • Decreased workload
  • Pressure
  • Inadequate nutrition
• Metaplasia


  A reversible change where one differentiated cell type is replaced by another cell type that is better able to withstand the adverse environment
• Metaplasia


  • Columnar to squamous epithelial metaplasia in respiratory tract
  • Squamous to columnar metaplasia in Barrett's esophagus
  • Connective tissue metaplasia like bone formation in muscle
• Reversible cell injury


  Functional and morphologic changes are reversible if the damaging stimulus is removed
• Causes of cell injury

  • Oxygen deprivation
  • Physical agents
  • Chemical agents and drugs
  • Infectious agents
  • Immunologic reactions
• Physical Agents


  • Mechanical Trauma
  • Extremes of Temperature (Burns and Deep Cold)
  • Sudden Changes in Atmospheric Pressure
  • Radiation
  • Electric Shock
• Chemical Agents and Drugs

  • Simple chemicals (glucose or salt in hypertonic concentrations)
  • Oxygen at high concentrations
  • Trace amounts of poisons (arsenic, cyanide, or mercuric salts)
• Other Potentially Injurious Substances

  • Environmental And Air Pollutants
  • Insecticides And Herbicide
  • Carbon Monoxide
  • Asbestos
  • Alcohol
  • Ever-Increasing Variety Of Therapeutic Drugs
• Infectious Agents


  • Submicroscopic Viruses
  • Tapeworms & Higher Forms of Parasites
  • Rickettsia, Bacteria, Fungi
• Immune system


  • Serves an essential function in defense against infectious pathogens
  • Immune reactions may also cause cell injury
• Injurious reactions to endogenous self-antigens are responsible for several autoimmune diseases
• Immune reactions to many external agents (viruses and environmental substances) are also important causes of cell and tissue injury
• Genetic Derangements

  • Extra chromosome, as in Down Syndrome
  • Single base pair substitution leading to an amino acid substitution, as in Sickle Cell Anemia
• Genetic defects


  May cause cell injury because of deficiency of functional proteins, such as enzyme defects in inborn errors of metabolism, or accumulation of damaged DNA or misfolded proteins
• DNA sequence variants that are common in human populations (polymorphisms) can also influence the susceptibility of cells to injury by chemicals and other environmental insults
• Nutritional Imbalances


  • Protein-calorie deficiencies
  • Excess of cholesterol
  • Obesity
• Nutritional problems can be self-imposed, as in anorexia nervosa (self-induced starvation)
• Necrosis


  An "accidental" and unregulated form of cell death resulting from damage to cell membranes and loss of ion homeostasis
• Necroptosis


  In some cases necrosis is also regulated by a series of signaling pathways, albeit largely distinct from those that are involved in apoptosis
• Apoptosis


  A form of "programmed cell death" where the cell kills itself by damaging its DNA or proteins beyond repair
• Apoptosis


  • Characterized by nuclear dissolution, fragmentation of the cell without complete loss of membrane integrity, and rapid removal of the cellular debris
  • Mechanistically, apoptosis is known to be a highly regulated process driven by a series of genetic pathways
  • Serves many normal functions and is not necessarily associated with cellular injury
• Morphologic Alterations in Cell Injury

  • Reversible Injury: Generalized swelling of the cell and its organelles, Blebbing of the plasma membrane, Detachment of ribosomes from the ER, Clumping of nuclear chromatin
  • Irreversible Injury: Necrosis