8.26:
The Effect of Aging on Tissues
Every day, cells in different tissues are prone to damage. The older, damaged cells are eventually replaced by new ones to maintain tissue health. With progressing age, tissues lose their regenerative capacity, accruing damage.
For example, by age 50, active hair follicles become fewer. Hair fall continues, but very few new hairs are generated, leading to hair thinning and baldness.
Aging is also accompanied by reduced metabolism, reduced physical activity, and hormonal changes that gradually lead to the loss of muscle and bone mass.
As bones, joints, and skin age, connective tissues produce lower levels of collagen and elastic fibers. This reduces their strength and elasticity, causing brittle bones and wrinkled skin.
Furthermore, the proteoglycan composition of cartilage changes with age. As a result, cartilage flexibility and shock absorption capacity decrease leading to diseases such as osteoarthritis.
With increasing age, the possibility of DNA damage and mutation increases, making cancer more common in the elderly.
8.26:
The Effect of Aging on Tissues
Several body functions deteriorate with age. The external signs of aging are easily identifiable. For example, the skin becomes dry, less elastic, and thins out, forming wrinkles. The skin of the face begins to appear looser due to a decrease in the levels of elastic and collagen fibers in the connective tissue. Additionally, melanin production in the hair follicle decreases with age, resulting in gray hair. Moreover, the senses of sight and hearing decline, so glasses and hearing aids may become necessary.
As the bones lose calcium and other minerals, the overall height of an individual diminishes with aging. The lubricating synovial fluid in joints reduces, and the cartilage thins, leading to stiffening of the joints.
Aging also impacts the nervous system,affecting thought process and memory. Such decline in brain functions can result in conditions, such as Alzheimer's disease. At the cellular level, aging is accompanied by the shortening of the chromosomal tips (telomeres) after each cell division in the stem cells. Thus, stem cells lose their ability to divide and regenerate, delaying wound healing.
Furthermore, the transport of oxygen or nutrients into the cell and waste removal from the cell become inefficient following changes in the cell membrane. This results in inadequate functioning of the tissues and organs, resulting in the weakening of the body. With aging, individuals may develop other age-related disorders such as arthritis, diabetes, cardiovascular diseases, and cancers.
Though aging and associated disorders are inevitable, exercise and healthy lifestyle habits can slow down the effects of aging on the body.
This text is adapted from Openstax, Anatomy and Physiology 2e, Section 4.6: Tissue Injury and Aging.