In cell biology and Pathophysiology, cellular congruity refers to changes made by a cell in retort to obstructive environmental changes.  The congruity may be physiologic(al) (normal) or pathologic(al) (abnormal). Five important models of congruity embrace atrophy, hypertrophy, hyperplasia, dysplasia, and metaplasia. Atrophy is a reduce in cell quantity. If plenty cells in an organ atrophy the total organ get reduce in quantity. Thymus atrophy during existing rational crop (childhood) is an specimen of physiologic atrophy.
Skeletal muscle atrophy is a vile pathologic congruity to skeletal muscle disappearance (invariably denominated "disappearance atrophy). Work and organs in-particular tender to atrophy embrace skeletal muscle, cardiac muscle, inferior sex organs, and the brain. Hypertrophy is an acception in cell quantity. If plenty cells of an organ hypertrophy so get the well organ. The core and kidneys own acceptiond impressibility to hypertrophy. Hypertrophy involves an acception in intracellular protein rather than cytosol (intracellular liquescent).
Hypertrophy may be caused by spontaneous signals (e. g. , draw-out) or trophic signals (e. g. , enlargement factors). An specimen of physiologic hypertrophy is in skeletal muscle after a while sustained importance behavior application. An specimen of pathologic hypertrophy is in cardiac muscle as a consequence of hypertension. Hyperplasia is an acception in the estimate of cells. It is the consequence of acceptiond cell mitosis, or dispersion. The two models of physiologic hyperplasia are reparatory and hormonal. Reparatory hyperplasia permits work and organ renovation.
It is vile in epithelial cells of the epidermis and interior, liver hepatocytes, curse gist cells, and fibroblasts. It occurs to a shorter quantity in curse, cartilage, and mitigate muscle cells. Hormonal hyperplasia occurs primarily in organs that endure on estrogen. For specimen, the estrogen-dependent uterine cells rafter hyperplasia and hypertrophy subjoined pregnancy. Pathologic hyperplasia is an abrecognized acception in cell dispersion. A vile pathologic hyperplasia in women occurs in the endometrium and is denominated endometriosis.
Dysplasia refers generally to abrecognized changes in cellular figure, quantity, and/or form. Dysplasia is not considered a gentleman congruity; rather, it is care to be connected to hyperplasia and is casually denominated "atypical hyperplasia. " Tissues apt to dysplasia embrace cervical and respiratory epithelia. Dysplasia repeatedly occurs in the proximity of cancerous cells, and it may be confused in the crop of confront cancer. Metaplasia occurs when a differentiated cell of a unmistakable model is replaced by another cell model, which may be short differentiated.
It is a alterable rule care to be caused by parent cell reprogramming. Parent cells are set in epithelia and embryonic mesenchyme of connective work. A characteristic specimen of metaplasia involves the changes associated after a while the respiratory hope in retort to life of irritants, such as smog or fume. The bronchial cells alter from mucus-secreting, ciliated, columnar epithelium to non-ciliated, squamous epithelium unfitted of secreting mucus. These transformed cells may grace dysplasic or cancerous if the rousing (e. g. , cigarette smoking) is not removed.