Mastering Chapter 5 homework

Which of these structures is properly matched with its mode of secretion?

A; holocrine ( Structure A is a sebaceous gland that secretes oily materials by complete rupture of the gland cells.)

New portions of a nail are produced at the cuticle.

False (The nail matrix is the thickened proximal portion of the nail bed responsible for nail growth. The cuticle is the part of the proximal skin fold, or nail fold, that projects onto the nail body.)

The biggest risk factor for the development of skin cancer is excessive exposure to ultraviolet radiation from sunlight. Exposure to the type of UV light emitted from a tanning bed is far less dangerous.

False (The single most important risk factor for skin cancer is overexposure to the UV radiation in sunlight and tanning beds. UV radiation damages DNA bases and appears to disable tumor suppressor genes, leading to the formation of cancerous cells. There is no such thing as a "healthy tan." Tanning beds use the same types of UV radiation found in natural sunlight, often at even higher intensities, to stimulate melanin production.)

Why does your skin remain red after a bad sunburn?

Inflammation causes increased blood flow.

Which of the following correctly describes a common feature of all structures labeled A through D in the figure?

Structures A, B, C, and D are located in the dermis (Each of the labeled structures is located within the dermal layer of the skin.)

Which of the following statements is INCORRECT?

Tactile cells anchor the skin to the underlying structures of the body. (This is the incorrect statement. Tactile cells, in conjunction with their sensory nerve endings, function as touch receptors. The hypodermis, not tactile cells, anchors skin to the body.)

Which of the following represents a difference between eccrine sweat glands and apocrine sweat glands?

The secretions of apocrine sweat glands contain more fat and protein than do the secretions of eccrine sweat glands. (Compared to the watery secretions of eccrine glands, apocrine sweat glands produce a more viscous secretion that is enriched with fats and proteins.)

Which of these epidermal layers would be LEAST likely to develop cancer?

a

What is the structure indicated by label E?

a dermal papilla (Dermal papillae are projections of the dermis that form indentations in the overlying epidermis.)

Which skin function is not correctly matched with the structure that accounts for that function?

apocrine gland: thermoregulation (While the function of the apocrine cells is not well understood, they do not provide much assistance in thermoregulation because of their location.)

Which of the following would be a sign of a melanoma?

asymmetry (Cancerous growths exhibit asymmetry. Benign growths exhibit symmetry, regular borders, uniform coloration, and they are usually less than 6 mm in diameter.)

Which of the following would not be a correct characteristic of melanoma?

border regularity (Border irregularity would be a sign of melanoma, especially if you were to see rough or notched edges.)

Which structure is a type of sweat gland?

c (Structure C is an eccrine gland, the most abundant type of sweat (sudoriferous) gland.)

Earwax is made by __________.

ceruminous glands (Ceruminous glands are modified apocrine sweat glands found in the lining of the external ear canal. Their secretion mixes with sebum produced by nearby sebaceous glands to form a sticky, bitter substance called cerumen, or earwax, which is thought to deter insects and block entry of foreign material.)

Cell division would be most common among cells in which of the labeled layers?

d (Cells migrate upwards through the epidermis after being generated by mitosis in the stratum basale.)

Layers B and C collectively form the __________.

dermis (Although layers B and C can be distinguished based on their structural components, they form a continuous layer of the skin termed the dermis)

Why would a third-degree burn be less painful than a first- or second-degree burn involving the same body area?

destruction of underlying pain receptors

What is the function of structure B?

detection of pressure stimulus (Structure B is a lamellar (Pacinian) corpuscle that responds to cutaneous contacts involving deep pressure.)

Part A Part complete Drag the appropriate labels to their respective targets.

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Drag the appropriate labels to their respective targets.

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Complete Part A Part complete Drag the appropriate labels to their respective targets.

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What is the most common cell type in the epidermis?

keratinocytes (Keratinocytes are the primary cells that form the stratified layers of the epidermis)

Which skin pigment is made in the skin as a natural defense against UV radiation?

melanin (Melanin is the only one of the three pigments (melanin, carotene, and hemoglobin) that contribute to skin color that is actually produced in the skin itself. Melanin protects the DNA of skin cells from UV radiation by absorbing the rays and dissipating the energy as heat.)

Which skin-color-associated, pigment-producing cell is located in the labeled layer D?

melanocyte (Melanocytes within the stratum basale produce the pigment melanin, which is deposited within the deeper layers of the epidermis)

The most dangerous type of skin cancer is __________.

melanoma (Melanoma, cancer of melanocytes, is the most dangerous skin cancer because it is highly metastatic and resistant to chemotherapy. These cancers appear spontaneously, and about one-third develop from preexisting moles.)

Which type of cell or cellular structure is not found in the epidermis?

pain receptors (Pain receptors formed by free nerve endings are found deep to the epidermis in the papillary layer of the dermis.)

Which of the following is NOT a function of sebum?

protection from UV radiation (This is false; it is melanin (not sebum) that protects the skin from the damaging effects of UV radiation. Sebum serves as a lubricant, an antibacterial agent, and protects against water loss.)

Which of the following is a layer of the epidermis found in thin skin?

reticular layer (The reticular layer is one of two layers of connective tissue that form the dermis of thin and thick skin.)

In general, skin cancer is least likely to develop in which of the following locations?

scalp (The skin of scalp has hair, which gives it added protection from the damaging ultraviolet rays of the sun.)

Which glands secrete an oily product that softens the skin and hair?

sebaceous glands (Sebaceous glands secrete an oily substance called sebum. Sebum softens and lubricates the hair and skin, slows water loss from the skin when external humidity is low, and has bactericidal properties.)

Susan sat out in the sun watching a baseball game. She developed small blisters on her unprotected shoulders and neck. What type of burn is represented by the formation of the blisters?

second-degree burn (Second-degree burns injure the epidermis and the superficial region of the dermis. Symptoms mimic those of first-degree burns, but blisters also appear.)

Pigment can be found in several layers of the epidermis. In which layer would you expect to find the cells that produce melanin?

stratum basale (10−25% of the cells in the stratum basale are melanin producing cells called melanocytes. Their branching processes extend among the surrounding cells, reaching well into the more superficial stratum spinosum layer.)

Which stratum of the epidermis contains the stem cells responsible for regenerating the more superficial layers?

stratum basale (The stratum basale is the deepest layer of the epidermis and consists of one layer of actively mitotic stem cells. The stem cells in this layer generate the cells that will migrate to the more superficial layers: spinosum, granulosum, and corneum.)

Which of the following terms describes layer D?

subcutaneous (The hypodermis ("under the skin") layer is also referred to as the subcutaneous region.)

Which of the following is a metabolic function of skin?

synthesis of a vitamin D precursor (Yes, this is a function of the skin carried out by chemical reactions in the skin. When sunlight bombards the skin, modified cholesterol molecules are converted to a vitamin D precursor, which is transported via the blood to the liver and kidneys, where it is converted into active vitamin D.)

Which dermal layer is responsible for the dermal properties of skin that are evident as cleavage lines?

the reticular layer (The thicker, deeper layer of the dermis, called the reticular dermis, is named for its network of collagen fibers. These collagen fibers run in various planes, but most run parallel to the skin surface. Separations, or less dense regions, between these bundles form cleavage (tension) lines in the skin.)

If a person were born without eccrine glands, what skin function would he or she have a hard time completing?

thermoregulation (Sweat is used for thermoregulation. As sweat is released onto the surface of the epidermis, heat from the body is conducted into the water. Water is a better conductor of heat than air is. As the sweat evaporates, the heat from the body dissipates into the environment.)

What is the function of the structure at A?

to lubricate hair and prevent infection (Structure A produces sebum, an oily secretion that coats the hairs and prevents infectious agents from penetrating the hair shaft)

Which of these is NOT a function of the layer at D?

to supply cells to replace those lost from the epidermis