*Once cell decreased in size, it has now compensated for the decreased blood supply, nerve supply, nutrient supply, hormonal supply, etc. has achieved a new homeostasis to survive. cells still alive but have diminished function- may lead to cellular death. Hypertrophy increase in size of cell; ultimately increase organ as well. hormonal stimulation or increased functional demand, increases cellular protein in plasma membrane, endoplasmic reticulum, myofilaments, and mitochondria (not cellular fluid). This ultimately leads to the increased cell size Triggers: Mechanical signals = stretch Tropic signals = growth factors and vasoactive agents Hyperplasia and hypertrophy may occur at same time IF cell is capable of mitosis Hyperplasia increase in the number of cells, not the size of increase in production of local growth factors and number of growth factor Cells such as nerve cells, skeletal muscle cells,
3 the cell, which results from an increased rate of cell division. *can only happen in cells that are capable of mitosis (cell division) cell receptors. This activates cellular genes which in turn increases the production of growth factors and cell receptors. The net result is cellular proliferation and an increase in the number of cells . myocardial cells and the lens of the eye cannot experience hyperplasia because they do not have the ability to reproduce. Dysplasia abnormal changes in the size, shape and organization of mature cells due to persistent, severe cell injury or irritation. characterized by disordered cell growth. called atypical hyperplasia. This is not a true adaptive process and can be considered one step beyond adaptation but not quite cancer. “pre-cancer.” Pap smears often show dysplastic cells of the cervix that must undergo laser type treatment, surgical treatment or close observation. Metaplasia reversible change in which one adult cell is replaced by another adult cell. results from exposure of cells to chronic stressors, injury or irritation. stimulus induces a reprogramming of stem cells. reprogramming done under influence of cytokines and growth factors. stem cell differentiates along new cellular pathway than what would have followed in absence of the stimuli. chronic smokers - normal ciliated epithelial cells of bronchial linings are replaced by stratified squamous epithelial cells. Barrett Esophagus is present when normal esophageal squamous epithelial cells are replaced by intestinal-like columnar cells . Cancers may arise a. Identify a physiologic and pathophysiologic example for atrophy, hypertrophy, hyperplasia, dysplasia, and metaplasia. Disease Physiologic Example Pathologic Example Atrophy Occurs w/ early development. Shrinking of thymus gland Atrophy of skeletal muscle in immobilized pt
4 during childhood Hypertrophy Increased muscle mass in someone lifting weights.
- Fall '15