Ageing is simply the process of becoming older. Superficially, as we age, we appear to have more wrinkles and blemishes in the skin, and perhaps grayer hair. We don’t have the same strength, endurance, and even body shape as we did when we were younger. But on a molecular and cellular level in the body, what is driving these changes?
Cells are the building blocks that form all
our tissues. As we age, our cells age too. Stem cells, which are cells that are
capable of becoming a range of different tissues (bone, muscle, blood, etc.),
lose the capacity to undergo differentiation—the ability to change from one
cell type to another. This is problematic because stem cells are responsible
for replenishing damaged tissue, for example, damaged cartilage in joints. So,
the body cannot regenerate as effectively.
Unlike the cells in young bodies, cells in
the older person’s body also lose some of their metabolic capacity and start to
accumulate waste proteins, resulting in malfunction. This is thought to occur
because of several different reasons:
DNA
damage arising from exposure to free radicals (free radicals are high-energy
molecules in the body
capable of destroying or damaging
other molecules). Shortening of
telomeres (telomeres are structures on the end of your DNA that protect it from
degradation). Advanced glycosylation end products (AGEs) (destructive molecules
created from sugar) abnormally bond with other normal proteins and fat
molecules, and over time, these altered molecules accumulate. Our cells may be
intrinsically programmed genetically to age and stop working.
Thus, the body loses its ability to replace
old or damaged cells, and those older cells start to malfunction. This disrupts
the complex biological processes in the body. Cellular aging processes affect
the musculoskeletal system, and we know that three things happen:
Bones lose
density, becoming weaker and more brittle (aka osteoporosis and osteopenia)
Muscle mass and density decreases (a.k.a. sarcopenia)
The smooth cartilage which covers our joints wears down. In the spine, all three of these processes occur in addition to degeneration of the intervertebral discs—the structures which are responsible for linking our vertebrae together.
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