The aging process
As aging takes place gradual and subtle changes in the structure and functions of various systems. These decreases in the reserve capacity of functional systems approach the threshold of dysfunction, and until the body has undergone significant stress, homeostatic mechanisms can cope with minimal fluctuations. In some cases, the disruption of adaptive capacity as a result of stressful effects leads to the development of diseases. At the same time, even for very old people, a reduction in the reserve capacity of functional systems should not be considered inevitable;the magnitude of reserves and the ability to adapt to internal and external stress factors can vary widely.
Aging is characterized by changes in a number of physiological parameters of the body. The following changes are most pronounced and typical [in comparison with the level of these indices in 30 years( 100%):
- decrease in the speed of carrying out nerve impulses by 5%;
- decrease in the level of basic metabolism by 18%;
- decrease of water content in the body by 20%;
- reduction in cardiac output by 30%;
- decreased GFR by 32%;
- decreased renal blood flow by 50%;
- reduction of the maximum capacity of lungs by 60%;
- reduction of maximum oxygen consumption by 63%;
- decrease in brain mass by 45%;
- decrease in the number of glomerular glomeruli by 45%;
- decrease in body weight by 15%, etc.
However, age-related changes in body organs and systems can develop at different rates. So, in the bone system they appear early, but proceed slowly, while in some structures of the central nervous system they are not found for a long time, but subsequently develop very quickly.
The age-related changes in the central nervous and neuroendocrine systems, which play a leading role in the regulation of metabolic processes and vital functions in the human body, are leading in aging.
Different methods of research, due to their ability to quantify the value of a parameter, can detect changes in indicators related to the functional and regulatory characteristics of organs and systems in the elderly, and thus help in establishing the biological age of a particular person and leading pathogenetic mechanisms of prematureaging.