Patho Ch 45 Integumentary
A school student with a rash goes to the school nurse for evaluation. The nurse suspects the student has contact dermatitis. The primary cell responsible for this delayed-type hypersensitivity reaction is: A. Merkel cells B. Reticular dermis C. Langerhans cells D. Dermal dendrocytes
A As antigen-presenting cells, the Langerhans cells are involved in delayed-type hypersensitivity reactions such as contact dermatitis and other cell-mediated immune responses in the skin; their dendritic processes extend through keratinocytes, forming a network to bind and process antigen. Merkel cells provide sensory information to the skin. In the dermis, the reticular dermis is a complex meshwork of three-dimensional collagen bundles that contain dermal dendrocytes, which have phagocytic properties.
While breaking in a new pair of shoes, a client develops a large (1.0 cm) blister filled with clear fluid. The dermatologist diagnoses this as: A. Bullae B. Wheal C. Nodule D. Vesicle
A Bullae are large (1.0 cm or larger in diameter) fluid-filled blisters, whereas vesicles are small (<1.0 cm in diameter). Nodules are solid marble-like lesions (>0.5 cm) that are deeper and firmer than a papule. A wheal is a somewhat irregular, relatively transient area of localized skin edema, such as a mosquito bite.
A dermatologist is explaining to a client the advantages of using a lotion that can draw out water to the skin surface. The nurse knows the technical term for this lotion is a/an: A. Occlusive B. Humectant C. Emollient D. Xerosis
A Humectants are the additives in lotions, such as α-hydroxy acids and urea, that draw out water from the deeper skin layers and hold it on the skin surface. Emollients are fatty acid-containing lotions that replenish the oils on the skin surface but usually do not leave a residue on the skin. They have a short duration of action and need to be applied frequently. Urea is a nitrogenous substance that has been quite effective in reducing xerosis when combined with lotions. It is a humectant at lower concentrations (10%), but in higher concentrations (20%-30%), it is mildly keratolytic. Occlusives are thick creams that contain petroleum or some other moisture-proof material. They prevent water loss from the skin.
When talking to a group of teenagers about ways to protect against skin damage from ultraviolet radiation, the nurse should discuss which of the following tissues/cells? A. Melanocytes B. Langerhans C. Subcutaneous fat D. Protein granule
A In addition to the keratinocytes, the epidermis has melanin pigment-producing melanocytes that protect against ultraviolet radiation and Langerhans cells that link the epidermis to the immune system. Subcutaneous tissue contains fat and binds the dermis to underlying body tissues. The third keratinocyte layer, the stratum granulosum, is composed of flat cells containing protein granules called keratohyalin granules.
With eyes closed, an object is placed in a student's hand. The instructor asks the student to identify the object. When he does so correctly, this is primarily the responsibility of: A. Meissner corpuscles B. Conical projections C. Prickle cell lesions D. Krause end bulbs
A Meissner corpuscles are encapsulated mechanoreceptors specialized for tactile discrimination. They are concentrated on the fingertips and palms of the hands, where they account for about half of the tactile receptors. The skin is also supplied by Krause end bulbs, nerve endings contained in a cylindrical or oval capsule. They are found most frequently in the oral cavity, conjunctiva, and genitalia. Although their function is uncertain, they are thought to act as mechanoreceptors and heat detectors. The stratum spinosum is two to four layers thick, consisting of cells commonly referred to as prickle cells because they develop a spiny appearance as their cell borders interact. The papillary dermis lies adjacent to the epidermis and is densely covered with conical projections called dermal papillae.
One of the best products for extremely dry skin on the elbows would be to apply which type of dressing? A. An occlusive with petroleum material mixed in the cream B. A humectant lotion that contains a α-hydroxy acid C. A lotion that has a corticosteroid in it D. A cream that has a lidocaine product mixed with it
A Occlusives are thick creams that contain petroleum or some other moisture-proof material. They prevent water loss from the skin. They are the most effective agents for relieving skin dryness. Humectants are the additives in lotions, such as a-hydroxy acids and urea, that draw out water from the deeper skin layers and hold it on the skin surface. However, the water that is drawn to the skin is transepidermal water, not atmospheric water; thus, continued evaporation from the skin can actually exacerbate dryness. α-Hydroxy acids are derived from fruits, hence the abundance of fruit additives in over-the-counter shampoos and lotions. Lotion or cream additives include corticosteroids or mild anesthetics, such as camphor, menthol, lidocaine, or benzocaine. These agents work by suppressing itching while moisturizing the skin.
When asking pathophysiology students, "Why do sebaceous glands secrete sebum?" the student with the correct answer would be: A. To lubricate skin and hair B. To supply energy in the form of fibrous protein C. To increase water amounts released via perspiration D. To supply a nutritional source for vitamin D
A Sebaceous glands secrete sebum, an oily mixture consisting of lipids, including triglycerides, cholesterol, and wax, that lubricates hair and skin. Keratinocytes of the epidermis produce a fibrous protein called keratin, which is essential to the protective function of skin. Sweat glands produce watery secretions. The dermis supports the epidermis and serves as its primary source of nutrition.
A teenager with bullous pemphigoid on the thighs asks, "What causes this blistering?" The best response by the nurse would be: A. "Your body has developed antibodies against basement membrane proteins." B. "You have been eating too much candy with large amounts of triglycerides." C. "The contraction of your arrector pili muscles causes this." D. "The lymph vessels are inflamed and responsible for this enlargement."
A The basement membrane zone is often involved in skin disorders that cause bullae or blister formation. One of these disorders, bullous pemphigoid, is a blistering disease caused by antibodies against basement membrane proteins. The thighs and flexor tendons are most commonly affected. The disease is self-limited but chronic, and the person's general health is unaffected. The sympathetic nervous system controls the arrector pili (pilomotor) muscles that cause elevation of hairs on the skin. Contraction of these muscles tends to cause the skin to dimple, producing "goose bumps." The basal cells of the epidermis project into the papillary dermis, forming rete ridges. Lymph vessels and nerve tissue also are found in this layer.
Which of the following characteristics differentiates apocrine sweat glands from eccrine sweat glands? A. Apocrine secretions contain oils. B. Apocrine secretions help maintain skin pH. C. Apocrine glands are more numerous and widely distributed than eccrine glands. D. Apocrine glands are primarily thermoregulatory.
A The major difference between apocrine glands and the eccrine glands is that apocrine glands secrete an oily substance. Apocrine glands are less widely distributed than eccrine glands, and they do not contribute as significantly to thermoregulation. Neither is a major contributor to skin pH.
Which of the following would be considered functions of the skin? Select all that apply. A. Protection against physical injury B. Protection from an invasion of microbes C. Regulation of acid-base balance D. Regulation of metabolism E. Synthesis of vitamin D
A, B, E Besides providing a covering for the entire body surface, the skin performs many other functions, including protection against physical injury, sunlight, and microorganisms; prevention of loss of fluids from the internal environment; regulation of body temperature; continual reception of sensations from the environment, such as touch, temperature, and pain; and synthesis of vitamin D through the action of sunlight on the skin. Acid-base regulation occurs primarily in the lungs and kidneys. Metabolic rate is regulated by many hormones, not the skin.
When explaining why some children have albinism, the science teacher explains that which enzyme is needed for synthesis of melanin? A. Laminim B. Tyrosinase C. Bradykinin D. Pheomalanin
B Although there are more than 10 different types of albinism, the most common type is recessively inherited oculocutaneous albinism, in which there is a normal number of melanocytes, but they lack tyrosinase, the enzyme needed for synthesis of melanin. The lamina lucida consists of fine anchoring filaments and a cell adhesion glycoprotein, called laminin, which plays a role in the organization of the macromolecules in the basement membrane zone and promotes attachment of cells to the extracellular matrix. Many chemicals have been found to produce the itch sensation, including histamine, serotonin, and cytokines. Substances such as bradykinin and bile salts act locally to stimulate the itch sensation. Localized concentrations of eumelanin are also responsible for the formation of freckles and moles. Pheomelanin, a reddish yellow pigment, is particularly concentrated in the lips, nipples, glans penis, and vagina.
A client complains to the health care provider that he keeps getting hard skin on the sides of the great and little toes when he wears certain pairs of shoes. This is probably caused by ill-fitting shoes putting pressure on certain areas of the foot and would be called a: A. Blister B. Corn C. Callus D. Hematoma
B Corns (helomas) are small, well-circumscribed, conical, keratinous thickenings of the skin. They usually appear on the toes from rubbing or ill-fitting shoes. The corn may be either hard (heloma durum) with a central hard, horny core or soft (heloma molle), as commonly seen between the toes. Blisters are circumscribed elevations of the skin caused by fluid under or within the epidermis. A callus is a hyperkeratotic plaque of skin that develops because of chronic pressure or friction. Hematomas are a mass of blood caused by a break in a blood vessel under the skin.
When asked to name the parts of the pilosebaceous unit of the skin, which student has the correct answer? A. Eccrine secretions B. Sebaceous glands C. Keratinized plates D. Connective tissues
B Most hair follicles are associated with sebaceous glands, and these structures combine to form the pilosebaceous unit. The nails are hardened keratinized plates. Eccrine sweat glands transport sweat to the outer skin surface to regulate body temperature. The subcutaneous tissue layer consists primarily of fat and connective tissues that lend support to the vascular and neural structures supplying the outer layers of the skin.
Which of the following clients would experience an accelerated rate of cell division in the stratum germinativum layer? A. A stroke client who is incontinent of stool and bladder B. A motorcycle accident client with large abrasions on the lower limbs C. A young athlete who experienced a torn cartilage in the knee D. A pregnant client who has developed dark purple stretch marks on the abdomen
B The deepest layer, the stratum germinativum, consists of a single layer of basal cells that are attached to the basal lamina in the basement membrane zone. The basal cells are the only epidermal cells that are mitotically active. It normally takes 3 to 4 weeks for the epidermis to replicate itself. The rate of cell division in the stratum germinativum is greatly accelerated when the outer layers of the epidermis are stripped away as occurs in abrasions and burns. The outer epidermis, which is avascular, is composed of four to five layers of stratified squamous epithelial cells, predominantly keratinocytes, which are formed in the deepest layer of the epidermis and migrate to the skin surface to replace cells that are lost during normal skin shedding. These are most affected by incontinence. Stretch marks are similar to stratum granulosum cells that have a dark staining granule of keratohyalin.
Due to the increasing dryness of her skin in recent years, a 70-year-old woman has needed to reduce the number of baths that she takes. Which of the following factors has resulted in this age-related change in skin function? A. Slower keratinization B. Changes in sebaceous secretions C. Dehydration of epidermal cells D. Increased production of bile salts
B The effects of aging on skin dryness include a change in the composition of sebaceous gland secretions and a decrease in the secretion of moisture from the sweat glands. Changes in the composition of keratinocytes and the process of keratinization do not account for the drier skin that accompanies aging. Deposition of bile salts on the skin surface causes pruritus and dry skin, but this is a pathologic process rather than an age-related change.
Which of the following statements about temperature regulation and skin is accurate? A. Since the skin is avascular, it is the subcutaneous layer that primarily is responsible for temperature control. B. Arteriovenous anastomoses between an artery and a vein within the skin layer are important for temperature regulation. C. It is primarily the arteries that bring blood from the heart that keeps the body temperature within a normal range. D. The lymphatic system of the skin is primarily responsible for heating and cooling the skin.
B The skin is richly supplied with arteriovenous anastomoses in which blood flows directly between an artery and a vein, bypassing the capillary circulation. These anastomoses are important for temperature regulation. The lymphatic system of the skin, which aids in combating certain skin infections, also is limited to the dermis.
A teenager has just been told by the dermatologist that he is high risk for developing skin cancer since he has natural red hair and fair skin. The physiology behind this statement may be due to the: A. Oversecretion of eumelanin, a brown-black pigment that causes tans B. Enhanced photoreactivity of pheomalanin, as compared to eumelanin C. Lack of pheomelanin pigmentation, which protects against skin cancer formation D. Increased susceptibility to photosensitivity due to oversecretion of melanin
B There are two major forms of melanin: eumelanin and pheomelanin. Exposure to the sun's ultraviolet rays increases the production of eumelanin, a brownish black pigment, which causes tanning to occur. An enhanced photoreactivity of the red melanin, pheomelanin, compared to the black melanin, eumelanin, is commonly invoked to explain why fair-skinned individuals are more susceptible to skin cancers. The primary function of such melanin is to protect the skin by absorbing and scattering harmful ultraviolet rays, which are implicated in skin cancers. Localized concentrations of eumelanin are responsible for the formation of freckles and moles. This does not mean that they will develop skin cancer. Pheomelanin, a reddish yellow pigment, provides color to the body when it is concentrated, primarily in the lips, nipples, glans penis, and vaginal areas. Photosensitivity refers to abnormal sensitivity (not reactivity) of the skin to ultraviolet light, usually following exposure to certain oral or topical drugs or to other sensitizing chemicals and resulting in accelerated burning and blistering of the skin. Both types of melanin are found in hair, particularly red hair. It has been suggested that the reason fair-haired individuals are more susceptible to skin cancers may be due to the enhanced photoreactivity of pheomelanin, as compared to eumelanin.
Following a camping trip, a client returns with multiple "bug bites" and skin rashes. The nurse should encourage which of the following interventions to decrease pruritus to prevent further spread of the rashes? Select all that apply. A. Obtain a prescription for opioids, so the client can sleep uninterrupted. B. Rub areas with the hand rather than using long fingernails. C. Take lots of very warm, soothing oatmeal baths. D. Use topical corticosteroid creams. E. Take antihistamines like Benadryl, especially at bedtime.
B, D, E Pruritus, or the unpleasant sensation of itch, is a symptom common to many skin disorders leading to the desire to scratch. Measures such as using the entire hand to rub over large areas and keeping the fingernails trimmed often can relieve itch and prevent skin damage. Self-limited or seasonal cases of pruritus may respond to treatment measures such as moisturizing lotions, bath oils, and the use of humidifiers. Because vasodilation tends to increase itching, cold applications may provide relief. Cool showers before bed, light sleepwear, and cool home temperatures also may be helpful. Mild cutaneous disorders, such as bug bites, are mediated by histamine; therefore, topical antihistamines tend to be the treatment of choice. Topical corticosteroids are effective as antipruritics, particularly when used for urticaria (hives) or insect bites. Opioids are for pain control and not itching. Very warm baths would increase the itching rather than decrease it.
Which of the following skin disorders is likely to result from the localized lack of melanin production by melanocytes? A. Rash B. Bullae C. Vitiligo D. Melasma
C In cases of vitiligo, depigmented areas may contain no melanocytes, greatly altered or decreased amounts of melanocytes, or, in some cases, melanocytes that no longer produce melanin. Melasma results from increased pigmentation, and neither bullae nor rashes are consequences of alteration in melanocyte function.
In third-world countries, many children experience uncontrolled itching and scratching, which may develop into: A. Blisters B. Vesicles C. Lichenification D. Ulcers
C Repeated rubbing and scratching can lead to lichenification (thickened and roughened skin characterized by prominent skin markings caused by repeated scratching or rubbing) or excoriation (lesion caused by breakage of the epidermis, producing a raw linear area). Blisters are circumscribed elevations of the skin caused by fluid under or within the epidermis. Pustules are circumscribed pus-filled elevations of the skin. Vesicles are small (<1.0 cm in diameter). An ulcer is a skin defect in which there has been loss of the epidermis and papillary layer of the dermis.
A skin care consultant informs the client that he needs to bathe and use a soft cloth to remove dead cells on the skin surface. The rationale for this action is based on the fact that A. All layers of epidermis undergo rapid mitosis. B. Cells of the stratum spinosum will turn into prickle cells if not removed by bathing. C. A basal cell is mitotically active and pushes older dead cells to the skin's surface. D. Keratinocytes will turn to fibrous protein tissue if not removed by bathing.
C The basal cells are the only epidermal cells that are mitotically active. All cells of the epidermis arise from this layer. As new cells form in the basal layer, the older cells change shape and are pushed upward toward the skin surface. The second layer, the stratum spinosum, is two to four layers thick. The cells of this layer are commonly referred to as prickle cells because they develop a spiny appearance as their cell borders interact. The keratinocytes are the predominant cell type of the epidermis. They produce a fibrous protein called keratin, which is essential to the protective function of skin and may be involved in the immune system and wound healing.
A 22-year-old male college student has presented to his campus medical clinic distraught at the emergence of numerous small blisters on the shaft of his penis. On examination, the clinician notes that the lesions are between 2 and 4 mm in diameter and are filled with serous fluid. The clinician would document the presence of: A. Pustules B. Macules C. Vesicles D. Papules
C Vesicles are less than 1 cm in diameter and filled with serous fluid, such as the lesions typical of herpes simplex. Macules are small variations in skin color that are nonpalpable, while pustules are filled with pus. Papules are small, solid masses.
In science class, a group of sixth graders are "freaked out" when they learn that nails grow continuously and are the end product of which of the following components? A. Hypertrophy of arrector pili muscle B. Anagen follicles C. Telogen phase D. Dead cells pushed outward from the nail matrix
D Like hair, nails are the end product of dead matrix cells that are pushed outward from the nail matrix. Unlike hair, nails grow continuously rather than cyclically. The arrector pili muscle, located under the sebaceous gland, provides a thermoregulatory function by contracting to cause goose bumps. Anagen hair has long inner roots and outer root sheaths, is deeply rooted in the dermis, is difficult to detach, and does not come out with regular brushing. Telogen hair has short, white, club-shaped roots. With formation of new anagen hair below the root, the developing follicle will eventually replace the telogen hair, leading to the shedding of approximately 50 to 100 hairs a day.
While lecturing about frostbite, the instructor asks the students, "Which substance prevents undue evaporation from the stratum corneum during the cold winter weather which then helps conserve body heat?" The most correct student answer is: A. A Langerhans cell, which produces antigen-presenting cells B. An eccrine sweat gland C. A nerve ending D. Sebum, secreted by the sebaceous gland
D Sebum lubricates the hair and skin, prevents undue evaporation of moisture from the stratum corneum during cold weather, and helps to conserve body heat. Langerhans cells are dendritic cells that reside principally in the stratum spinosum of the epidermis and play a major role in the functioning of the skin's immune system. Their major function is to phagocytose and process foreign antigens. Most hair follicles are associated with sebaceous glands, and these structures combine to form the pilosebaceous unit. Langerhans cells are not paired with hair follicles, and apocrine, not eccrine, glands are often associated with a hair follicle. Nerve endings are widely distributed throughout the skin, but these are not paired with hair follicles.
A 14-year-old presents to the dermatologist clinic with a severe case of acne. The nurse explains that this acne is a result of inflamed A. Follicular bulbs B. Dermal papillae C. Apocrine glands D. Sebaceous glands
D The sebaceous glands are the structures that become inflamed in acne. Growth of the hair is centered in the bulb (i.e., the base) of the hair follicle, which is just one part of the hair structure. Apocrine sweat glands are located deep in the dermal layer and open through a hair follicle. Dermal papillae minimize separation of the dermis and the epidermis and contain capillary venules that nourish the epidermal layers of the skin.