Download - Cellular pathology
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Cellular Pathology
“All organ injuries start with structural or molecular alterations in cells” concept
began by Virchow in 1800's.
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NORMAL CELL
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NORMAL CELL
• present day study of disease attempts to understand how cells react to injury.
• at the subcellular or molecular level.
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NORMAL CELL
• all cells share the basic organelles for the synthesis of proteins, lipids, carbohydrates; energy production.
• transport of ions and other substances.• to understand pathology, review normal
structure and function of cells.• “you cannot appreciate the abnormal before you understand
the normal”
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Plasma membrane
• phospholipid bilayer with embedded proteins / glycoproteins / glycolipids.
• semipermeable membrane with pumps for ionic / osmotic homeostasis
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Nucleus
• nuclear envelope / nuclear pores• chromatin (euchromatin vs heterochromatin)• nucleolus (synthesis of ribosomal RNA)
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Mitochondria
• inner & outer membranes, cristae• intermembranous and inner matrix
compartments• oxidative phosphorylation (main source of
ATP)
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Endoplasmic reticulum (ER), Ribosomes & Golgi Apparatus
• rough (RER) vs smooth (SER) endoplasmic reticulum
• ribosomes (free in cytosol or attached to RER)• polysomes (threaded by mRNA).• condensing vacuoles / secretory vesicles
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Lysosome• enzymatic (acid hydrolases) digestion of
materials in the cell• endocytosis• phagocytosis / phagosome; pinocytosis /
pinocytotic vesicle; receptor-mediated endocytosis
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Peroxisome
• enzymes (eg catalase, oxidases) ! metabolism of hydrogen peroxide & fatty acid
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CELL ADAPTATION, CELL INJURY and CELL DEATH
• DEFINITIONS AND TERMINOLOGY
• Homeostasis : cells are able to maintain normal structure and function (eg ion balance, pH, energy metabolism) in response to normal physiologic demands.
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Cellular Adaptation
• as cells encounter stresses, either excessive physiologic demand or some pathologic stimuli, they may make functional or structural adaptations to maintain viability / homeostasis.
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Cellular Adaptation
• cells may respond to these stimuli by either increasing or decreasing their content of specific organelles.
• adaptive processes: atrophy, hypertrophy, hyperplasia and metaplasia are forms of adaptation.
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Cell Injury
• if the limits of adaptive response are exceeded, or in certain instances when adaptation is not possible, a sequence of events called cell injury occurs.
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Cell Injury
• a) Reversible Cell Injury• removal of stress will result in complete
structural and functional integrity to be restored.
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Cell Injury → Cell Death
• Irreversible Cell Injury / Cell Death• if stimulus persists (or severe enough from the
start) the cell will suffer irreversible cell injury and death.
• cell death is one of the most crucial events in pathology and can affect any type of cell.
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Cell Death
• Necrosis: type of cell death characterized by severe membrane injury and enzymatic degradation; always a pathologic process.
• Apoptosis: regulated form of cell death; can be physiologic or pathologic process.