Aging-related anatomical and physiological changes start several years before the appearance of external signs. Several of these changes start appearing around our forties and continue to do so until our organism can no longer adapt itself. The process of senescence, on the physiological level, causes the decline of organic functions, followed by the aging of tissue and of the body’s general appearance.
All of the organism’s muscles, those in the torso and the extremities, in particular, atrophy with time, which leads to a general deterioration of muscular tone as well as a loss of power, strength, endurance and agility. Total muscle weight decreases by half from 30 to 70 years of age. Muscle aging is due to muscle fibers atrophying and an increase in intramuscular fat content. Muscles in the forearms lose the most strength.
Muscular strength, at 80 years old, has decreased by 30%. We have less strength and resistance, we lift lighter weights, we have less strength to open jars or for cleaning (mopping, vacuuming, moving furniture).
Our joints also undergo changes: ligaments calcify, ossify, and joints shrink through the erosion of cartilaginous surfaces. Whereas some joints become more rigid as they deteriorate, others become more flexible.
Even though they keep their appearance, bones also undergo changes. The process of calcium reabsorption becomes unbalanced and the bony tissue becomes more porous and fragile due to continuous demineralization. Osteoporosis is also one of the factors responsible for tooth loss, which is in fact connected to the inflammation and demineralization of the bone surrounding the tooth. Those teeth which remain become flatter, and the jaw atrophies, which makes the teeth appear longer and further apart. Bone resorption in the jaw and maxilla accentuates with tooth loss. The distance between the chin and nose shortens and teeth move backwards, in time changing the physiognomy of the elderly individual.
Height loss is another phenomenon which can be attributed to aging. It is actually due to the spine shortening (by 1.2 to 5 cm) through the slimming of the dorsal and lumbar vertebrae as a result of osteoporosis. This phenomenon, which is more pronounced in women than in men, begins during our fifties and is related to the interaction of different factors such as age, sex, race and environment. The shortening of the spine skews the body’s proportions, the arms and legs remaining the same size, which causes a deviation of the upper thorax and accentuates the spine’s natural curvature (kyphosis). In order to keep their balance, elderly people need to lean forward and slightly bend their knees in order to maintain their center of gravity. Cartilage wears out with time and these curvatures become permanent. The thoracic cavity becomes smaller and the ribs move down and out. The reduction of the rib cage is linked to the osteoporosis of the ribs and atrophying respiratory muscles. It decreases respiratory amplitude, which explains the posture which is often observed: “torso pushed forward, head tilted back”. This inward arching of the body changes our appearance, hinders mobility and accentuates the elderly person’s shorter body.
For women, breasts sag and atrophy, and the nipples sometimes become inverted. The sebaceous glands which produce protective sebum become less active and lubricate the skin less, and it becomes dry and brittle as a result. The sweat glands become less active as well, and modify how body temperature is controlled by sweat.
The loss of subcutaneous fatty tissue is one of the clearer outcomes of aging. This phenomenon is common to all aging individuals and particularly affects the arms and legs. Tendons, veins and joints in the hands, as well as in our clavicles, protrude more, along with our ribs and knees. The cavities in our armpits and above our clavicles are accentuated. The maxillary bones are more visible, the cheekbones are more salient, and our eye sockets deepen. Our nose, ears and earlobes become longer, our eyelids and cheeks sag. In addition to atrophying and becoming less elastic, the skin undergoes other changes. Here are a few: the appearance of colored spots on the epidermis (lentigo senilis), of purpura, (bruising due to fragility of the dermis and blood vessels), the presence of senile telangiectasia (permanent dilation of small subcutaneous blood vessels), drying and flaking of the skin.
With age, changes in the balance of androgen and estrogen (hormones) occur, and lead to many changes: hair rarefies all over the body and falls little by little; in certain places, like the pubic area, armpits and extremities (feet and hands), hair loss is almost complete. Both men and women often see hair appear on the face however. For women, it mostly grows on the chin and upper lip, whereas for men, it will grow in the ears and nostrils; this unsightly hair is abundant and coarse, and often forces women to wax or shave it off; moreover, for certain elderly people, eyebrow hair becomes very thick and coarse.
The hair on our scalp also changes drastically during aging. Although hair loss is normal, it accentuates as we age. We have the most hair when we are 40. From this age onwards, the process reverses. Baldness, or the gradual thinning of our hair, is linked to racial and hormonal genetic predispositions. It affects men more often than women, and can begin as early as in our twenties. When we age, our hair changes appearance, becomes more scarce, thinner, weaker and has less volume. It gradually grays, half of people aged 50 or older having gray or graying hair. This discoloration is linked with lowered melanocyte activity. These cells produce melanin, a hair coloring agent. Nails also change. Their growth slows down, followed by the appearance of longitudinal striations and grooves on their surface, to which is added lowered peripheral circulation, all of which together make nails grow thicker, drier and more brittle; this phenomenon is even more pronounced for toenails.