Structure and Physiology

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This section covers some of the anatomic and physiologic changes that are attributed to aging, as well as some of the physical findings that result.

Skin

There is atrophy of the epidermis, hair follicles, and sweat glands, which results in thinning skin. The skin becomes fragile and discolored. Wrinkling and dryness result from reduced skin turgor. In addition, the nails become thin and brittle, with marked ridging. There is decreased vascularity of the dermis, which contributes to prolonged healing time. There are common pigmentary changes, such as the development of senile lentigines, or ''liver spots.'' These brown macules are commonly found on the backs of the hands, forearms, and face. They are caused by localized mild epidermal hyperplasia, in association with increased numbers of melanocytes and increased melanin production. Figure 25-1 shows senile lentigines on the hand of an 87-year-old woman.

Another common skin change is senile (solar) keratosis, which is a well-defined, raised papule or plaque of epidermal hyperkeratosis. The surface scale varies in color from yellow to brown. These lesions are common on the face, neck, trunk, and hands. Figure 25-2 shows several senile keratoses on an 82-year-old man.

There is commonly a degeneration of the elastic fibers and collagen of the skin, resulting in a loss of elasticity and the development of senile purpura. These purple macules, commonly seen on the backs of the hands or on the forearms, result from blood that has extravasated through capillaries that have lost their elastic support. Figure 25-3 shows senile purpura on the forearm of a 90-year-old woman.

Sebaceous gland hyperplasia, especially on the forehead and nose, is common. These yellowish glands range in size from 1 to 3 mm and have a central pore. It is important to differentiate these benign lesions from basal cell carcinomas.

Hair loses its pigment, which commonly results in ''graying'' of the hair. With the reduction in the number of hair follicles, there is hair loss all over the body: head, axilla, pubic area, and extremities. With the reduction in estrogens, an increase in hair may actually develop in many older women, especially on the chin and upper lip. Chin hairs on a 79-year-old woman are shown in Figure 25-4.

Figure 25-1 Senile lentigines in an 87-year-old woman. Notice the well-demarcated, brownish-black macules.

Figure 25-1 Senile lentigines in an 87-year-old woman. Notice the well-demarcated, brownish-black macules.

Senile PurpuraSenile Old Man
Figure 25-2 Raised senile keratoses on the face and neck of an 82-year-old man.

As a result of the reduction in subcutaneous tissue, there is less insulation and less padding over bony surfaces. This predisposes older people to hypothermia and the development of pressure sores, or decubitus ulcers. Figure 25-5 shows a pressure sore that developed on an 85-year-old man within 1 week. The man had been seen 1 week earlier when a small, intact erythematous area was noticed over his sacral area. He was brought back to the emergency department 7 days later with the decubitus ulcer seen in the figure. The ulceration eroded through the skin and muscle, into the sacrum, and into the bowel, with the development of a rectovesicular fistula.

Eyes

As a result of a reduction of orbital fat, the eyes appear sunken. Laxity of the eyelids, or senile ptosis, often develops. Ectropion or entropion may develop, caused by the lower eyelid's falling away or falling inward, respectively. There may also be a clogging of the lacrimal duct, resulting in epiphora, or tearing. Fatty deposits in the cornea may produce an arcus senilis, seen in Figures 10-53 and 10-54. Inadequate production of mucous tears by the conjunctiva may predispose persons to corneal ulcers, exposure keratitis, or dry eye syndrome.

An accumulation of yellow pigment in the lens alters color perception. A loss of elasticity in the lens results in presbyopia. Nuclear sclerosis of the lens develops into cataract formation.

Senile Loss Elasticity
Figure 25-3 Senile purpura on the forearm of a 90-year-old woman. Note the red macules and the loss of turgidity of the skin.

Figure 25-4 Chin hairs on a 79-year-old woman.

Figure 25-4 Chin hairs on a 79-year-old woman.

Patients experience a decrease in visual acuity and commonly complain of sensitivity to glare from interior lights, sunlight, or reflection from floors.

Degenerative changes in the iris, vitreous humor, and retina may impair visual acuity, reduce the fields of vision, and lead to the development of floaters (muscae volitantes). Senile macular degeneration (see Figs. 10-121 to 10-123) and retinal hemorrhages are other medically significant causes of decreases in visual acuity.

Ears

Degeneration of the organ of Corti may result in presbycusis, an impaired sensitivity to high-frequency tones. Patients experience a slowly progressive hearing loss with a consistent pattern of pure tone loss. Otosclerosis may produce conductive deafness, as does the excessive cerumen accumulation so commonly seen in older individuals. A degeneration of the hair cells in the semicircular canals may produce vertigo.

Nose and Throat

Atrophic changes occur in the mucosa of the nose and throat. Taste and especially smell may be altered, particularly in institutionalized individuals. A decrease in mucus production predisposes older patients to upper respiratory infections. A loss of elasticity in the laryngeal muscles may produce tremulousness and high pitch of the voice.

Figure 25-5 A stage IV pressure sore in the sacral area of an 85-year-old man. Note the sacrum (white area) and necrotic surrounding muscles.

Figure 25-5 A stage IV pressure sore in the sacral area of an 85-year-old man. Note the sacrum (white area) and necrotic surrounding muscles.

Accidentes Vivo Pulidores

Mouth

Loss of teeth from dental caries or periodontal disease is common. Gingival recession may produce problems with dentures and a malalignment of bite. Atrophic changes in the salivary glands cause dryness of the mouth, known as xerostomia, a common complaint among the elderly.

Lungs

A loss of elasticity in the pulmonary septa and atrophy of the alveoli cause a coalescence of the alveoli, with a reduction in vital capacity and oxygen diffusion. There are decreases in forced vital capacity and expiratory flow rate. A degeneration of bronchial epithelium and mucous glands increases the susceptibility to infections. Skeletal changes also contribute to a decrease in vital capacity.

Cardiovascular System

A loss of elasticity of the aorta may cause aortic dilation. The semilunar and atrioventricular valves may degenerate and become regurgitant. Alternatively, these valves may become sclerotic, which causes stenosis of the valves. Degeneration or calcification of the conducting system may cause heart block or arrhythmias.

Noncompliance of the peripheral arteries may cause hypertension with a widened pulse pressure. Systolic blood pressure rises progressively with age, whereas diastolic pressure levels off in the sixth decade of life; these developments lead to an increased prevalence of isolated systolic hypertension. Coronary atherosclerosis may produce angina, myocardial infarction, or nonspecific symptoms such as confusion or tiredness.

There are also decreases in plasma volume, ventricular filling time, and baroreflex sensitivity.

Breasts

The amount of glandular tissue decreases, and the tissue is replaced by fatty deposits. As a result of a loss of elastic tissue, the breasts become pendulous, and the ducts may be more palpable.

In men, gynecomastia may result from a change in the metabolism of sex hormones by the liver (see Fig. 16-21).

Gastrointestinal System

Atrophy of the gastrointestinal mucosa occurs with a reduction in the number of stomach and intestinal glands, causing alterations in secretion, motility, and absorption. Changes in elastic tissue and colonic pressures may result in diverticulosis, which can lead to diverticulitis. Pancreatic acinar atrophy is common, as are decreases in hepatic mass, hepatic blood flow, and microsomal enzyme activity. These decreases result in an increased half-life of lipid-soluble drugs.

Genitourinary System

There is a decrease in the number of glomeruli and a thickening of the basement membrane in Bowman's capsule, resulting in a reduction in renal function. Degenerative changes occur in the renal tubules, which themselves are reduced in number. Renal blood flow is reduced to half by 75 years of age. Vascular changes may also contribute to a reduced glomerular filtration rate.

In men, prostatic atrophy or prostatic hypertrophy develops. Benign prostatic hypertrophy is present in 80% of all men older than 80 years. The penis decreases in size, and the testicles hang lower in the scrotum.

In postmenopausal women, the reduction in estrogen is associated with an increase in susceptibility to osteoporosis. The labia and clitoris are reduced in size, and the vaginal mucosa becomes thin and dry. The uterus and ovaries also decrease in size.

As discussed previously, pubic hair decreases in amount and becomes gray.

Endocrine System

There is decreased metabolism of thyroxine and decreased conversion of thyroxine to triiodo-thyronine. Because of a reduction in pancreatic beta cell secretion, hyperglycemia may result. The hypothalamus and the pituitary gland secrete reduced amounts of hormones. An increase in the secretion of antidiuretic hormone and atrial natriuretic hormone may alter fluid balance. There are also increased levels of norepinephrine.

Musculoskeletal System

There is general atrophy of muscles, causing a decline in strength. Muscle wasting is seen most commonly in the distal extremities, especially in the dorsal interosseous muscles.

Osteoclastic activity is greater than osteoblastic activity. An enlargement of the cancellous bone spaces and a thinning of the trabeculae result in osteoporosis. Kyphosis and a loss of height are common (see Fig. 13-6). Degenerative changes and a loss of elastic tissue occur in joints, ligaments, and tendons. This frequently results in joint stiffness. Degenerative changes in bone may result in bone cysts and erosions, making these bones prone to fracture. Osteoarthritis is common. Thinning of cartilage and synovial thickening produce joint stiffness and pain. Range of motion is also reduced, perhaps because of pain. Figure 20-59 shows Heberden's and Bouchard's nodes in an 86-year-old woman with osteoarthritis.

Nervous System

Changes in brain function may adversely affect memory and intelligence, although other skills such as language and sustained attention may remain. Significant variability exists among individuals, and many elderly individuals continue to perform at levels that are comparable with or exceed those of much younger people.

Brain weight is frequently reduced 5% to 7% as a result of atrophy of selected areas. There is a decrease in blood flow to the brain by 10% to 15%. Vascular changes of atherosclerosis can result in multiple infarcts or transient ischemic attacks.

Reflexes are commonly reduced;the gag reflex is frequently absent. The Achilles tendon reflex is often symmetrically reduced or absent. Primitive reflexes, such as snout or palmomental, may be present in normal elderly persons.

Hematopoietic System

There is an increase in the amount of marrow fat and a decrease in the amount of active bone marrow.

Immune System

There is a decreased number of newly formed T lymphocytes and a reduced capability of T lymphocytes to proliferate in response to mitogens or antigens. Humoral immunity is impaired, and suppressor T lymphocytes are decreased in number.

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