General pathology lecture 4 cellular adaptation
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Cellular adaptations can occur through hyperplasia, hypertrophy, atrophy, or metaplasia in response to stress or changes in workload or stimulation. Hyperplasia involves an increased number of cells through cell proliferation. Hypertrophy involves cellular enlargement without an increase in cell number. Atrophy is a decrease in cell size. Metaplasia is the replacement of one adult cell type with another. Examples provided include uterine hyperplasia during pregnancy, cardiac hypertrophy in hypertension, muscle fiber atrophy after injury or disuse, and squamous metaplasia in the lungs of smokers. Dysplasia refers to alterations in cell size, shape, and organization and is a pre-cancerous condition.
General pathology lecture 4 cellular adaptation
- 1. CELLULAR ADAPTATION Lecture 4
- 2. Normal +Stress Adapted cell Cell - Stress Stress = ? Increased/decreased workload * skeletal muscle and body building * cardiac muscle and hypertension * skeletal muscle disuse (limb immobilization) Increased/decreased stimulation
- 3. Adapted Cell Cellular adaptations to stress 1. Hyperplasia (more cells) 2. Hypertrophy (bigger cells) 3. Atrophy (smaller cells)
- 4. 3. Atrophy (smaller cells) 1. Physiologic During development: i.e. notochord; thyroglossal duct 2. Pathologic (local or generalized) via * disuse * Loss of endocrine stimulation * denervation * Aging * ischemia * Pressure
- 5. Atrophy (Mechanism) Reduction in structural components Decreased number of mito, myofilaments, ER via proteolysis (lysosomal proteases; ubiquitin- proteosome system) Increase in number of autophagic vacuoles Residual bodies (i.e. lipofuscin brown atrophy)
- 10. Normal Artophied Brain atrophy
- 11. Muscle fiber atrophy. The number of cells is the same as before the atrophy occurred, but the size of some fibers is reduced. This is a response to injury by "downsizing" to conserve the cell. In this case, innervation of the small fibers in the center was lost. This is a trichrome
- 12. DISUSE ATROPHY (Poliomyelitis)
- 15. Hyperplasia (more cells) 1. Physiologic * Hormonal (breast/uterus in pregnancy) * Compensatory (liver after partial hepatectomy) 2. Pathologic Excessive hormone/GF stimulation of target tissue * Endometrial hyperplasia (x’s estrogen)
- 16. Hyperplasia (Mechanism) Cell proliferation via increased production of TRANSCRIPTION FACTORS due to * Increased production of GF * Increased levels of GF receptors * Activation of intracellular signaling
- 21. Adapted Cell 2. Hypertrophy (larger cells) * Not due to swelling * Increased synthesis of structural components * Results in larger organ
- 22. HYPERTROPHY OF SMOOTH MUSCLE IN ASTHMA
- 23. CARDIAC HYPERTROPHY Myocardial hypertrophy. - Cross-section of the heart of a patient with long- standing hypertension - Shows pronounced, concentric left ventricular hypertrophy
- 26. Question Which term is most likely to fit the description of the uterus during pregnancy? A. hyperplasia B. hypertrophy C. aplasia D. dysplasia E. metaplasia
- 27. Metaplasia (Mechanism) Reprogramming 1. of stem cells present in normal tissues 2. of undifferentiated mesenchymal cells in connective tissue Mediated by signals from cytokines, Growth Factor Leading to induction of specific transcription factors
- 29. 4. Metaplasia **One adult cell type replaces another** Reversible Columnar to squamous epithelium (most common epithelial -type of metaplasia) Chronic irritation i.e. (in trachea and bronchi of smokers) Vit A deficiency squamous metaplasia in respiratory epithelium
- 30. Photomicrograph of the junction of normal epithelium (1) with hyperplastic transitional epithelium (2).
- 31. Photomicrograph of the trachea from a smoker. Note that the columnar ciliated epithelium has been replaced by squamous epithelium.
- 32. METAPLASIA-LUNGS
- 33. DYSPLASIA-Left • Cellular dysplasia refers to an alteration in the size, shape and organization of the cellular components of a tissue. • It is established that dysplasia is a preneoplastic lesion, in the sence that, it is a necessary stage in the multi-step cellular evolution to cancer.
- 34. DYSPLASIA
- 35. DYSPLASIA-CERVIX
- 36. Question Which of the following best describes the phenomenon of epithelial dysplasia? A. an increase in thickness of the epithelium because of increased number of cells B. a decrease in thickness of the epithelium owing to decrease in the number of dividing cells C. an irregular proliferation and maturation of cells throughout the layers of the epithelium D. an increase in the thickness of the epithelium owing to enlargement of the component cells E. absence of epithelium because of lack of cell proliferation
- 38. Muscular Dystrophy • What Is Muscular Dystrophy? Muscular dystrophy is a disease in which the muscles of the body get weaker and weaker and slowly stop working because of a lack of a certain protein (see the relationship to genetics?) • Can be passed on by one or both parents, depending on the form of MD (therefore is autosomal dominant and recessive)
- 39. ANAPLASIA
- 40. • Next Meeting: • Study Inflammation and Repair
Editor's Notes
- #5: Diminished function but not dead.
- #6: Glucocorticoids, thyroid hormone and TNF stim proteosome-mediated protein degradation; insulin opposes
- #9: Kidney: atrophy via renal artery stenosis. NB: decrease in cortex (most metabolically active cells)
- #16: Hormonal: Breast at puberty; breast and uterus during pregnancy Compensatory: regeneration of liver after partial hepatectomy NB; hyperplasia regresses if stim removed; difference with cancer
- #20: Lft: normal thyroid gland: rings of epithelial cells surrounding colloid. Rt: hyperplasia/hypertrophy of Graves d; note epithelial projections into colloid.
- #22: Hypertrophy
- #25: Middle = normal heart; left = hypertrophied heart due to hypertension; rt = dilated heart due to inability to adapt to continued stress
- #30: Squamous thought to be more durable cell type Squamous epithelium don’t mucus Acid reflux col to squamous metaplasia (Barrett esophagus) Connective tissue metaplasia = formation of bone, cart, or adipose tissue in tissues that normally don’t contain them