Anti aging guide

Immunity and aging

 

 

Everyday experience enables us to detect the difference in the texture of veal and beef, and the distinctive properties of perished rubber and old glue or plastic. These physical changes also characterize aging connective tissue, which becomes stiff and loses its previous elasticity. This is thought to be due to chemical cross-linkages which form bridges between adjacent collagen molecules, accounting for the features we observe in the skin, tendons, and muscle sheathes as we grow older. Other physical changes are caused by proteins in the lens of the eye, called crystalline, which become joined together by increasing numbers of disulphide bonds during the formation of a cataract.

Homeostasis is the series of mechanisms by which the body retains its chemical composition and its physical characteristics despite changing external conditions and despite variations in intake of fluid and salts. These mechanisms depend on the autonomic nervous system and on the kidneys, among other organs. The capacity to maintain homeostasis seems to be impaired in the frail elderly, who become much more liable to hypothermia and falls in blood pressure and to loss of body water. Indeed the ability of the kidney to conserve water has been thought to decline steadily throughout adult life, although this belief is currently being disputed.

The efficiency of the immune system shows a distinct tendency to decline in old age, as was tragically illustrated by the Christmas 1989 influenza epidemic in the UK. This decline probably also contributes to the increasing prevalence among the old of diseases, other than infections, including cancer. Galen regarded the involution (wasting) of the thymus, an organ situated near the heart, as the earliest sign of aging. This process commences in childhood, and the blood cells (T-lymphocytes) which are processed in the thymus and which are vital constituents of the immune system, function less well in old people. Animals who are subjected to the removal of the thymus age rapidly and die early.

Posted by Carol Hudgens - April 19, 2012 at 4:59 pm