HISTOPATH Lec Mod 1

• Schaffer and Emerson's 1964 study on attachment:

  • Aim: identify stages of attachment / find a pattern in the development of an attachment between infants and parents
  • Participants: 60 babies from Glasgow
  • Procedure: analysed interactions between infants and carers
  • Findings: babies of parents/carers with 'sensitive responsiveness' were more likely to have formed an attachment

  
• Attachment is a strong reciprocal emotional bond between an infant and a primary caregiver

  
• Pathology is the study of disease, focusing on the structural, biochemical, and functional changes in cells, tissues, and organs that underlie disease
• Purpose of pathology:

  • Explain the signs and symptoms manifested by patients
  • Provide a rational basis for clinical care and therapy
  • Serve as a bridge between basic sciences and clinical medicine
• Pathology has two traditional divisions:

  • General Pathology: concerned with common reactions of cells and tissue to injurious stimuli, not tissue-specific
  • Systemic Pathology: examines alterations and underlying mechanisms in organ-specific diseases
• Four aspects of the disease process in pathology:

  1. Etiology: cause of the disease (genetic or acquired)

  2. Pathogenesis: sequence of biochemical and molecular events following exposure to injurious agents

  3. Morphologic changes: structural alterations induced in cells and organs, used for diagnostic purposes

  4. Clinical Manifestations: functional consequences of the disease, leading to signs and symptoms
• Basic terms in pathology:

  • Disease: a pathophysiological response to internal and external factors
  • Disorder: a disruption of normal body functions
  • Syndrome: a disease or disorder with multiple identifying features or symptoms
• Schaffer and Emerson's 1964 study on attachment:

  • Aim: identify stages of attachment / find a pattern in the development of an attachment between infants and parents
  • Participants: 60 babies from Glasgow
  • Procedure: analyzed interactions between infants and carers
  • Findings: babies of parents/carers with 'sensitive responsiveness' were more likely to have formed an attachment
• Cellular response to stress and toxic insults involves adaptation, injury, and death

  
• Adaptations are reversible functional and structural responses to changes in physiologic states and some pathologic stimuli
• Forms of adaptations in response to environmental changes:

  • Hypertrophy: increase in cell size, can be physiologic or pathologic
  • Hyperplasia: increase in cell number, can be physiologic or pathologic
  • Atrophy: decrease in cell size, can be physiologic or pathologic
  • Metaplasia: replacement of one differentiated tissue by another
• An image showing a fetus with anencephaly, a neural tube defect resulting in the absence of a major portion of the brain, skull, and scalp

  
• Cell injury occurs when cells are exposed to injurious agents or stress, deprived of essential nutrients, or compromised by mutations affecting essential cellular constituents
• Cell injury is reversible up to a point, but if the injurious stimulus is persistent or severe, the cell suffers irreversible injury and cell death may ensue
• Cell death can occur through two pathways: necrosis and apoptosis; nutrient deprivation triggers an adaptive cellular response called autophagy that may also culminate in cell death
• Causes of cell injury include hypoxia, free radical injury, chemical cell injury, infectious agents, immune system reactions, and genetic abnormalities
• Reversible cell injury is due to decreased ATP generation, loss of cell membrane integrity, defects in protein synthesis, cytoskeletal damage, and DNA damage

  
• Morphology of reversible cell injury under the light microscope includes cellular swelling, small clear vacuoles in the cytoplasm (hydropic change or vacuolar degeneration), increased eosinophilic staining, and fatty change manifested by appearance of lipid vacuoles in the cytoplasm
• Reversible cell injury is characterized by plasma membrane swelling, ER dilation, mitochondrial changes, clumping of nuclear chromatin, and cellular swelling under the light microscope
• Cell death can occur through necrosis or apoptosis, with necrosis resulting from degradative and inflammatory reactions after tissue death caused by injury
• Necrosis morphology includes coagulative necrosis, liquefactive necrosis, caseous necrosis, gangrenous necrosis, fibrinoid necrosis, and fat necrosis
• Cells undergo programmed cell death called apoptosis when they are no longer needed or become a threat to the organism
• Apoptosis is an orderly cell death process that causes the cell to shrink, condense, disassemble its cytoskeleton, and alter its cell surface for rapid digestion by phagocytic cells
• Physiological apoptosis includes the destruction of cells during embryogenesis, hormone-dependent tissue involution, cell loss in proliferating cell populations, and elimination of harmful self-reactive lymphocytes
• Pathological apoptosis eliminates cells that are injured beyond repair without eliciting a host reaction, thus limiting collateral tissue damage
• Morphological features of apoptosis include cell shrinkage, chromatin condensation, formation of cytoplasmic blebs and apoptotic bodies, and phagocytosis of apoptotic cells or cell bodies usually by macrophages
• Intracellular accumulations may occur due to metabolic alterations within the cell, leading to the accumulation of various substances in abnormal amounts
• Main pathways of abnormal intracellular accumulations include inadequate removal of normal substances, accumulation of abnormal endogenous substances, failure to degrade metabolites, and deposition of abnormal exogenous substances
• Fatty change is characterized by the accumulation of intracellular triglycerides and is observed most frequently in the liver, heart, and kidney
• Cholesterol and cholesterol esters can accumulate in cells, leading to conditions like atherosclerosis, xanthomas, cholesterolosis, and Niemann-Pick disease type C
• Excess proteins within cells can cause morphologically visible accumulation with diverse causes
• In cholesterol trafficking, there can be cholesterol accumulation in multiple organs
• Excess proteins within cells can cause morphologically visible accumulation and have diverse causes
• Reabsorption droplets in proximal renal tubules are seen in renal diseases associated with protein loss in the urine (proteinuria)
• In disorders with heavy protein leakage across the glomerular filter, there is increased reabsorption of the protein into vesicles, appearing as pink hyaline droplets within the cytoplasm of the tubular cell
• Proteins that accumulate may be normal secreted proteins produced in excessive amounts, as seen in certain plasma cells engaged in active synthesis of immunoglobulins
• Defective intracellular transport and secretion of critical proteins can lead to diseases like α1-antitrypsin deficiency, causing emphysema
• Accumulation of cytoskeletal proteins includes types like microtubules, thin actin filaments, thick myosin filaments, and intermediate filaments divided into five classes
• Aggregation of abnormal proteins can lead to deposits in tissues, interfering with normal functions, and causing pathologic changes
• Intracellular hyaline change is caused by nonspecific accumulations of proteinaceous material with a characteristic homogenous, glassy, and eosinophilic appearance