What changes take place in the integumentary system postpartum

Summary

The integumentary system undergoes multiple changes with age but is more profoundly affected by the multiple comorbid conditions and systemic medications that occur with increasing frequency in advanced age. Once acquired, wounds undergo the same fundamental cascade of reactions and events to progress to closure in older adults but there are more factors that can slow the process of wound healing in the older populations. The physical therapist is an essential member of the wound care team in any setting and can employ his or her knowledge of therapeutic exercise, mobility rehabilitation, and environmental adaptations. The management of chronic wounds should often include the thoughtful application of physical agents to augment and speed the healing process. As the demographics of the United States shift toward a greater population of older adults, the absolute number of older adults with impaired integumentary integrity will also likely increase; physical therapists must be prepared to meet the challenge of collaborating with other health care workers to facilitate wound healing in older adults.

Integumentary System

The integumentary system, consisting of the skin, hair, nails, sebaceous (oil), and sweat glands, has a protective and regulatory function and, indirectly, an aesthetic one as well. Smooth, healthy, and vibrant skin, hair, and nails are appreciated, sought after, and rewarded in our society. For the individual, the integrity and appearance of the integument have important implications in terms of self-appraisal, self-esteem, and self-confidence.

There are noticeable changes associated with primary aging. As we age, there is a decrease in the number of hair follicles, a slowing in the rate of growth of the follicles that remain, and a decrease in the production of melanin. These changes contribute to the loss, but, because hair also shields the scalp from the effects of the sun, the loss and thinning of hair also impair its protective function against exposure to sunlight.13

As the largest organ in the human body, the skin protects internal organs and serves as a barrier to infectious organisms and to noxious and injury-producing agents. The skin also prevents dehydration from the loss of water and is an important part of the immune system.13,14 Through sensory receptors in the skin, we are able to detect temperature, pain, touch, and pressure. Through sweat glands and superficial blood vessels, the skin is able to cool the body and regulate its internal temperature.14,15

Loss of collagen and elastin, proteins that help the skin maintain its elasticity and tone, contribute to the thinning, sagging, and wrinkling of the skin, which we recognize as signs of aging. In primary aging, normal thinning of the epidermis combined with fragile capillaries and loss of fatty tissue increase the risk of bruising in older adults. These normal changes are further exacerbated in the presence of chronic conditions, such as diabetes, and the use of medications to treat these conditions. Changes precipitated by chronic conditions and medications are not normally experienced by all individuals and are associated with secondary aging.16 These physiological and structural changes in the integumentary system make aging skin more vulnerable to injury and can increase the risk of adverse health outcomes for aging persons. As an example, fatty tissue, which normally cushions the skin, becomes thinner as we age. Aesthetically, this accounts for the structural changes in the face and the aged appearance of hands and feet (Fig. 3.2). Physiologically, the loss of fatty tissue increases the risk of injury to the skin and, combined with a decrease in sweat production, interferes with the skin's ability to effectively regulate the body's internal temperature. Functionally, the loss of padding in the feet can cause pain and discomfort while walking13 and can have implications as to the elder's tolerance for footwear and even his or her activity level.

The sluggish replacement of epidermal cells and a decline in the production of melanin decrease the skin's ability to protect against exposure to the sun's ultraviolet rays and increase the risk of sunburn and skin cancer in elders.13 Blood supply to the skin, also reduced as we age, impairs wound healing and interferes with what we recognize as signs of inflammation, such as redness and swelling, which is the body's way to alert us of an infection or injury. Injuries to the skin caused by infection or sunburn may go unnoticed in elders, and treatment may be delayed or not provided.

Inefficient temperature regulation as a result of the reduction in sweat glands and loss of fatty tissue increases the risk of heat stroke in the aged.13 Loss of sensory receptors in the skin affects sensitivity to touch, temperature, and pain, making the elder more susceptible to cuts, abrasions, and burns. These changes in sensory receptors are also responsible for an increase in pain threshold and impaired pain localization in elders and, as in the case of injury to the skin, can preclude prompt intervention and treatment.

Nutrition and hydration play an important part in maintaining the integrity of the skin and other components of the integumentary system. The frailty and decreased resilience of aging skin are further compromised by the use of prescription and over-the-counter medications that make it more susceptible to the effects of sun exposure, more prone to bleeding, and less able to heal. COTAs need to be particularly cautious when working on transfers with elders to prevent skin injuries. Avoiding and addressing pressure areas from splints and braces, from prolonged sitting and improper seating equipment, or from confinement to bed can prevent complications from wounds that endanger the health and well-being of elders.

10.11 Oxidative Stress, the Integumentary System, and Skin Appendages

The integumentary system is a complex organ system composed of numerous components (skin, hair, nails, and glands). It functions primary to protect the body from the external environment, excrete waste, and regulate temperature. Moreover, skin produces vitamin D and a variety of hormones, such as growth factors and sex steroids. Skin mirrors the first sign of aging. With aging, dysfunction of this system may occur, resulting in increased dryness of the skin, thinning, age spots, wrinkles, and decreased skin elasticity. With time, the epidermis develops an abnormality in permeability barrier homeostasis, which is further accentuated in photo-aged skin. Commonly, wound healing disorders due to comorbidities are also encountered in the elderly. The sebaceous glands responsible for sebum production and lubrication of the skin lose their morphological as well as functional characteristics with aging. Elderly people are also characterized by a significant reduction in sweat output, and higher core and skin temperatures, as well as a reduction in sensory thermal sensitivity. With advanced age, the capacity of the skin to synthesize vitamin D from the sunlight also declines [48]. Skin aging can be classified into two broad categories: intrinsic aging and extrinsic aging. Hereditary genetic influences probably contribute to no more than 3% of aging, making epigenetic and post-translational mechanisms the most important pathway of aging. Human skin is constantly exposed to air, solar radiation, environmental pollutants, and mechanical and chemical insult, which are capable of inducing oxidative stress. Extrinsic skin damage develops due to several factors, including ionizing radiation, exposure to UV radiation, severe physical and psychological stress, alcohol intake, poor nutrition, and exposure to environmental pollutions. UV radiation results in photochemical generation of reactive oxygen species, mainly superoxide anion, hydrogen peroxide, hydroxyl radical, and singlet oxygen, all of which can cause skin damage and skin aging [49]. Air pollutants such as car exhaust can induce oxidative stress in human skin. Skin may also be exposed to oxidative stress due to physical damage to the skin, such as burns and wounds. The endogenous sources of reactive oxygen species are xanthine oxidase and nitric oxide synthase (which can produce nitric oxide directly in the skin), which can cause further skin damage. Therefore, oxidative stress plays a role in aging of the skin [50].

Wound Healing and the Biomedical Burden of Its Dysfunction

The integumentary system serves several key functions including protecting deeper structures, regulating temperature, providing a barrier against external pathogens, excreting wastes, and acting as a sensory interface with the outside world. The importance of this system is underscored by the complex repair mechanisms that have evolved to restore tissue integrity after injury. Wound repair requires the immediate activation of numerous overlapping pathways and cell types to synchronously clear debris, produce extracellular matrix (ECM), and revascularize the injured area. Just as importantly, these processes must be effectively shut down once the wound is healed.

The enormous biomedical and financial burden of wounds emphasizes the importance of understanding the mechanisms governing wound healing and designing effective therapies to improve outcomes. Surgical incisions are performed during an estimated 80 million and 250 million operations in the United States and worldwide, respectively, with an additional 12 million lacerations treated in US emergency departments each year [1–3]. Each injury, whether iatrogenic or traumatic in etiology, activates a common pathway of wound healing, where deposition of cells and ECM restores skin integrity. However, the deposited tissue is predominantly composed of fibroblasts and collagen, resulting in a patch of nonfunctional fibrotic tissue, known as scar. This tissue protects deeper structures from desiccation and foreign pathogens but lacks the original architecture and function (glands, nerves, hair follicles, etc.) present in unwounded skin.

In contrast, injured fetal skin up to 6 months of gestation and some eukaryotic organisms retain the ability to regenerate skin with structure and function nearly identical to the original tissue [4,5]. These regenerative processes are not present in adult humans, with evolution favoring accelerated wound closure and subsequent scar formation over restoration of function, architecture, and appearance. This is likely due to the survival benefits associated with rapid restoration of tissue integrity, minimization of blood loss, and prevention of infection. The net effect in adult humans is that even wounds that heal “perfectly” are inferior to uninjured skin. The resulting scar possesses 80% of the tensile strength of innate skin and, if anatomically located in proximity to joints or orbits, may result in functional impairment as the scar contracts [6].

The mechanism of cutaneous wound healing with the resultant deposition of fibrotic tissue is similar to the response to injury found in tissue throughout the body. While ECM deposition in the skin can cause problematic “scar,” fibrosis in organs such as the heart, lung, or liver can result in end-stage organ dysfunction. The molecular mechanisms discovered through cutaneous wound healing research therefore have potential impact in virtually every organ system. This chapter provides an overview of normal and impaired wound healing, highlights some of the clinical and research challenges, and describes current and developing therapies to improve the response to injury.

Integumentary System

The integumentary system is commonly referred to as the skin. Anatomically, the skin provides the physical end border of our being and is in direct contact with the environment. The skin provides the first line of defense against infection by sealing and protecting the underlying organ systems from invasion of pathogenic organisms.

Some authorities describe the skin as a complex membrane composed of a highly vascular (blood vessels) dermis covered by multiple layers of cells known as the epidermis (Figure 2.2). The portion of the epidermis next to the dermis which has access to blood supplying nutrients goes through rapid cell replication, pushing the cells up and away from the dermis and blood supply. Because the epidermis is avascular, the cells begin to die. The outermost layer of the epidermis is the corneum which is continuously flaking off inasmuch as it contains the oldest dead cells that have been pushed up and away from the blood supply of the dermis several weeks ago.

The skin’s complex design varies in different parts of the body. In addition to protecting the other systems from infection and dehydration, it contains highly organized receptors discriminately distributed throughout the body surface dedicated to signaling the central nervous system (CNS) of changing environmental conditions such as temperature or the compression of a brick falling on you. When the brain and/or spinal cord integrates the signals (nerve impulses) received from the skin, it will send signals to the appropriate organ systems for response.

One of the most significant coordinating efforts for the brain is to organize the activation of selective sweat glands which will assist the body to adapt to the environmental stimulus. As mentioned earlier, maintenance of body temperature is most important in maintaining an internal homeostatic environment so the body organs can function in an orchestrated way. If temperature is increasing due to the contraction of muscles in sporting activities or in life-threatening reactions, many sweat glands must be activated to increase water evaporation which will prevent the temperature from increasing to levels unsupportable for living functions.

It must be noted that sweat glands on the palms of the hand and soles of the feet are designed to increase grasping effectiveness needed during times of arousal whether in sporting activities or defensive activities. Sweat glands on the hands and most of the body are classified as eccrine or merocrine type. However, sweat glands under the arms and in the genital areas are classified as apocrine sweat glands that secret body fluids containing unique body chemicals which generate characteristic odors which become our signature. These odors are easily recognized by family dogs and other animals. Interestingly, these glands do not become active until puberty which can lead to sexual attraction to the opposite sex. In more primitive times, these glandular secretions were often advance signals that strangers, either friend or foe were nearby. Furthermore, these glandular secretions become the host diet for many bacteria which can create even more odoriferous signals. More details of the eccrine and apocrine gland activity can be reviewed in published physiology texts.

Eccrine sweat gland activity on the palmer surface of the hand and fingers contributes very significant signal value in the PDD assessment. As mentioned above, when a subject is aroused, an increase in grasping capacity is warranted. When the brain perceives such a circumstance, it will signal the sweat glands of the hand to increase secretion to better achieve the grasping demand. The neurophysiological map of how the brain directs the activity of sweat gland function is reasonably well understood and will be discussed briefly in the Nervous System section.

When the eccrine sweat glands secrete sweat it contains salt (NaCl), which enhances the secretion of water and the consequent evaporation cooling process. Salt is known in the physiological and medical disciplines as an electrolyte because NaCl, in a watery environment such as the body, separates into two particles called sodium and chloride ions.

For many decades, behavioral scientists have come to a widely held understanding that cognitive and emotional activity in the brain will increase sweat gland activity to enhance the grasping capacity of the hand anticipating some form of combat. The increase in sweat gland activity is assessed by monitoring electrolyte production. This is achieved by placing two surface electrodes on the skin and conducting a minute electric current between them. If the production of the salt electrolytes increases, the current passing between the electrodes will increase. This increase in conductivity between two electrodes placed on the palmer surface of the hand observed in neurophysiology research has been accepted and researched further by the PDD scientific community.

The fundamental science underlying the recording of skin conductance or its reciprocal, skin resistance, is described as Ohm’s Law, often written in the equation I = V/R. “I” equals current, “V” equals voltage or power (force), and “R” equals resistance. As a simple model, if you envision rolling a ball on a ground surface of wood, sand, or ice. These surfaces would represent R in the equation. V would be the force applied to the ball, and I would be the speed of the ball. Clearly, the ball would roll fastest on the ice and slowest on the sand because of the lower resistance of ice compared to sand to the force applied to the ball.

In skin conductance, if more sweat containing the salt electrolytes is produced at any given time, the current (I) between two electrodes will increase because the resistance is reduced. This reaction is observed as electrodermal activity (EDA). If the amplitude of the recording increases, it is the result of more sweat gland activity which reduced the resistance between the electrodes on the skin surface permitting an increase in current. The measurement of resistance can be calculated also but it is a more complicated measure. The original work on electrical resistance was done by the eighteenth century Italian researcher Luigi Galvani. Most modern psychophysiologists prefer to assess conductance rather than resistance activity because it is a more direct and simple measure of sweat gland activity.

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How does pregnancy affect the integumentary system?

What happens to the skin after pregnancy?