This document summarizes cellular pathology by discussing normal cell structure and function, as well as how cells adapt, become injured, and die in response to stress or disease. It states that understanding normal cells is crucial to appreciating abnormalities and outlines the basic organelles shared by most cells, including the plasma membrane, nucleus, mitochondria, endoplasmic reticulum, ribosomes, Golgi apparatus, lysosomes, and peroxisomes. It then defines homeostasis, cellular adaptation, reversible and irreversible cell injury, and the types of cell death including necrosis and apoptosis.

1. Cellular Pathology“All organ injuries start with structural or molecular alterations in cells” concept began by Virchow in 1800's.

2. NORMAL CELL

3. NORMAL CELLpresent day study of disease attempts to understand how cells react to injury.at the subcellular or molecular level.

4. NORMAL CELLall 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”

5. Plasma membranephospholipid bilayer with embedded proteins / glycoproteins / glycolipids.semipermeable membrane with pumps for ionic / osmotic homeostasis

6. Nucleus nuclear envelope / nuclear poreschromatin (euchromatinvsheterochromatin)nucleolus (synthesis of ribosomal RNA)

7. Mitochondriainner & outer membranes, cristaeintermembranousand inner matrix compartmentsoxidative phosphorylation (main source of ATP)

8. Endoplasmic reticulum (ER),Ribosomes & Golgi Apparatusrough (RER) vs smooth (SER) endoplasmic reticulumribosomes(free in cytosol or attached to RER)polysomes(threaded by mRNA).condensing vacuoles / secretoryvesicles

9. Lysosomeenzymatic (acid hydrolases) digestion of materials in the cellendocytosisphagocytosis/ phagosome; pinocytosis / pinocytotic vesicle; receptor-mediated endocytosis

10. Peroxisomeenzymes (egcatalase, oxidases) ! metabolism of hydrogen peroxide & fatty acid

11. CELL ADAPTATION, CELL INJURY and CELL DEATHDEFINITIONS AND TERMINOLOGYHomeostasis : cells are able to maintain normal structure and function (eg ion balance, pH, energy metabolism) in response to normal physiologic demands.

12. Cellular Adaptationas cells encounter stresses, either excessive physiologic demand or some pathologic stimuli, they may make functional or structural adaptations to maintain viability / homeostasis.

13. Cellular Adaptationcells 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.

15. Cell Injuryif the limits of adaptive response are exceeded, or in certain instances when adaptation is not possible, a sequence of events called cell injury occurs.

16. Cell Injurya) Reversible Cell Injuryremoval of stress will result in complete structural and functional integrity to be restored.

17. Cell Injury -> Cell DeathIrreversible Cell Injury / Cell Deathif 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.

19. Cell DeathNecrosis: 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.