Physiologic changes of the integument system
The integumentary system is the largest organ system in the human body, responsible for protection from physical and environmental factors. The integumentary system is both a barrier and a sensory organ, and includes the skin (the largest bodily organ), as well as appendages, sweat and sebaceous glands, hair, nails and arrestors pillorum (tiny muscles at the root of each hair that cause goose bumps).
Fetal Skin Formation
Fetal skin forms from three layers: ectoderm, mesoderm, and neural crest cells. Figure 1 shows a diagram of the skin structure.
At 4 weeks gestation, simple ectoderm epithelium forms. Between 4 and 12 weeks, the basal cells divide repeatedly to form the stratified epithelium while the mesoderm forms the blood vessels and connective tissues. Epidermal ridges (e.g. fingerprints) begin to develop around 10 week’s gestation and are completed by 17 weeks gestation. Sensory nerves also develop.
At 16 weeks gestation, the basement membrane folds. Melanoblasts that form melanocytes migrate with neural crests cells to the epithelium and begin producing melanin prior to birth. The connective tissue differentiates into the various layers of the dermis. Ectoderm thickens into fingernails and toenails. Other regions of the ectoderm form into epithelial columns called cords which become hair follicles and sebaceous and sweat glands.
At 20 weeks gestation, hair begins to grow from sebaceous glands, while sweat glands are formed from coiled cords. Other cords begin to form mammary glands.
Effects of Aging on the Integumentary System
The integumentary system undergoes intrinsic and extrinsic cutaneous aging, primarily involving the dermis.
Intrinsic Aging
The effects of intrinsic aging are caused solely by internal factors. Sometimes called chronological aging, intrinsic aging is an inherent degenerative process due to declining physiologic functions and capacities. This may include qualitative and quantitative changes such as diminished or defective synthesis of collagen and elastin in the dermis. As skin ages, it becomes thinner and more easily damaged. Intensifying this effect is the decreasing ability of skin to heal itself with age. Skin aging is also noted by a decrease in volume and elasticity and the increased incidence of wrinkles. Aging skin receives less blood flow and lower glandular activity. Cortisol (associated with stress) causes degradation of collagen, accelerating the aging process.
Extrinsic Aging
Extrinsic aging of skin is caused by external factors such as ultraviolet radiation, cigarette smoking, and air pollution. Of all extrinsic causes, radiation from sunlight has the most widespread documentation of negative effects on the skin. Because of this, extrinsic aging is often referred to as photo aging, defined as skin changes caused by chronic exposure to UV light. Photo damage implies changes beyond those associated with aging alone. It is defined as cutaneous damage caused by chronic exposure to solar radiation and is associated with emergence of neoplastic (cancer) lesions. Photo aging causes two main concerns: an increased risk for skin cancer, and the appearance of damaged skin. In younger skin, sun damage will heal faster since the cells in the epidermis have a faster turnover rate, while in older adults, thinner skin and slower healing may result in damage to the dermal layer
Expected Age-Related Changes
With aging, the epidermis becomes more fragile, increasing the risk for skin damage such as tears, maceration, and infection. Rashes caused by contact with chemicals, such as detergents or cosmetics, are increasingly common in older individuals. Skin repairs more slowly in older than in younger individuals, increasing the risk for infection.
Melanocyte activity declines with age, and in light-skinned individuals, the skin may become very pale, making older individuals more susceptible to the effects of the sun. Clusters of melanocytes can form areas of deepened pigmentation, a condition called senile lentos; these areas are often referred to as age spots or liver spots and are most often seen on areas of the body that are most exposed to sunlight. In a condition called seborrheic keratosis, slightly raised, warlike macules with distinct edges appear. These lesions, which can range in color from light tan to black, are most often observed on the upper half of the body, and they may cause discomfort and itching. Skin tags, or cutaneous papilloma, are small, brown or flesh-colored projections of skin that are most often observed on the necks of older adults.
Seborrheic keratosis usually appear at approximately the fifth decade of life and gradually increase in number with age. These superficial, benign growths can enlarge to 20 mm in diameter and have a convoluted surface.
Aging results in decreased elastin fibers and a thinner dermal layer with the loss of elasticity, the skin starts to become less supple. “Crow’s feet,” or wrinkles, develop. Skin that is very dry or that has had excessive exposure to sunlight or harsh chemicals is more likely to wrinkle at a younger age. Hair color tends to fade or “gray” because of pigment loss, and hair distribution patterns change. Color changes, and hair loss patterns tend to be hereditary. The hair on the scalp, pubis, and axilla tends to thin in both men and women. Hairs in the nose and ears often become thicker and more noticeable. Some women experience the growth of facial hair, particularly after menopause. Fingernails grow more slowly, may become thick and more brittle, and ridges or lines are commonly observed. Toenails may become so thick that they require special equipment for trimming. Sweat gland function decreases, and thus the amount of perspiration decreases. This results in heat intolerance because the body’s cooling system through the process of evaporation is less efficient.
Integumentary Changes Associated with Aging
| Physiologic Change | Results |
| Decreased vascularity of dermis | Increased pallor in white skin |
| Decreased amount of melanin | Decreased hair color (graying) |
| Decreased sebaceous and sweat gland function | Increased dry skin; decreased perspiration |
| Decreased subcutaneous fat | Increased wrinkling |
| Decreased thickness of epidermis | Increased susceptibility to trauma |
| Increased localized pigmentation | Increased incidence of brown spots (senile lentigo) |
| Increased capillary fragility | Increased purple patches (senile purpura) |
| Decreased density of hair growth | Decreased amount and thickness of hair on head and body |
| Decreased rate of nail growth | Increased brittleness of nails |
| Decreased peripheral circulation | Increased longitudinal ridges of nails; increased thickening and yellowing of nails |
| Increased androgen/estrogen ratio | Increased facial hair in women |
| Nursing Assessments | Care Strategies |
| Monitor skin temperature. | Adjust room temperature and provide adequate clothing or covers to prevent chilling. |
| Assess skin turgor over sternum or forehead, not forearm. Check tongue for furrows. | Provide adequate fluid to prevent dehydration. |
| Assess for skin breakdown or changes in color or pigmentation. | Institute measures to reduce pressure over bony prominences; possible dermatology referral. |
| Assess areas where skin surfaces touch and trap moisture (under breasts, adipose rolls, etc.) for signs of maceration or yeast infection. | Keep skin dry. Pad surfaces to reduce friction. Report abnormal observations for treatment. |
| Determine adequacy of hygiene and need for toenail trimming. | Modify skin care to reduce drying. |
Nursing Assessments and Care Strategies Related to Integumentary Changes
A decrease in the function of sebaceous and sweat gland secretion increases the likelihood of dry skin, or xerosis, Dry skin is probably the most common skin-related complaint among older adults, particularly when it is accompanied by itching, or pruritus. This problem is often more severe on the lower extremities because of diminished circulation.
