Atrophy

Atrophy is a general Physiological process of reabsorption and breakdown of Tissues , involving Apoptosis on a Cell ular level. It can be part of normal body development and Homeostatic processes, or as a result of Disease ,or loss of trophic support due to other disease is termed ''pathological atrophy''.

ATROPHY EXAMPLES

In normal development

Examples of atrophy as part of normal development include shrinkage and involution of the Thymus in early childhood and the Tonsils in adolescence.

Atrophy of the Breast s can occur with prolonged Estrogen reduction, as with Anorexia Nervosa or Menopause . Atrophy of the testes occurs with prolonged use of enough exogenous Sex Steroid (either Androgen or Estrogen ) to reduce Gonadotropin secretion. The Adrenal Gland s atrophy during prolonged use of exogenous Glucocorticoid s like Prednisone .

Disuse

''Disuse atrophy'' of Muscle s and Bone s, with loss of mass and strength, can occur after prolonged immobility, such as extended Bedrest , or lack of use of an organ (living in darkness for the eye, bedridden for the legs, etc). This type of atrophy can usually be reversed with exercise unless severe. Astronauts must exercise regularly to minimize atrophy of their limb muscles while they are in microgravity.

Pathologic

Pathologic atrophy of muscles can occur due to diseases of the motor nerves, or due to diseases of the muscle tissue itself. Examples of atrophying nerve diseases include CMT (Charcot Marie Tooth syndrome) Poliomyelitis , Amyotrophic Lateral Sclerosis ( ALS or Lou Gehrig's Disease ), and Guillain-Barre Syndrome . Examples of atrophying muscle diseases include Muscular Dystrophy , Myotonia Congenita , and Myotonic Dystrophy .

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Atrophy