A&P 106: Chapter 5 - Integumentary System

Why are lines of cleavage clinically significant?

A cut parallel to a cleavage line will remain closed. A cut parallel to a cleavage line will remain closed, which makes these lines important when making incisions. This parallel incision will minimize scarring since the wound will tend to remain closed. This also minimizes damage to the tissue itself since fewer elastic fibres will be cut. Cleavage lines do not promote fibrosis. Wounds do not heal more slowly if they run parallel to lines of cleavage. A cut at right angles to a line of cleavage will not remain closed.

Which of the following is an orange-yellow pigment that is found in certain food items, such as carrots and squash? A. Carotene B. Lentigo C. Melanin D. Keratin

A. Carotene Carotene is the orange-yellow pigment found in vegetables such as squash and carrots. This phytochemical functions in the human body as a pigment that may accumulate in the skin in the form of beta-carotene. Since this is a provitamin form of vitamin A, this accumulation has little risk for causing hypervitaminosis. Keratin is a tough, fibrous protein. Melanin is a dark brown pigment made in the skin. Lentigo is an area of abnormal pigmentation.

The color of the nail bed underneath the body of the nail is due to__________.

Blood vessels The nail body, the visible portion of the nail, covers an area of epidermis called the nail bed. Underlying blood vessels in the nail bed area give the nail its characteristic pink color, due to blood flow. When a person has a heart attack or blood flow is very poor, the color of the nail can become blue, as in cyanosis.

When ruptured dermal blood vessels leak into the dermis, a __________ may form.

Bruise When ruptured dermal blood vessels leak into the dermis, a bruise may form. The dark discoloration that is characteristic of a bruise is due to the leakage of erythrocytes outside blood vessels and into tissue spaces. As more blood accumulates, the region becomes darker. As the erythrocytes and the hemoglobin within them begin to break down, this color changes from a dark red to shades of green and black as clotting ensues.

Which type of gland produces earwax?

Ceruminous gland Ceruminous glands produce earwax. Earwax is also known as cerumen, and, like most secretions that line tracts and ducts, it has a protective function. Mammary glands produce milk. Sebaceous glands produce an oily secretion used for lubrication. Apocrine sweat glands produce a watery secretion in the armpits and pubic region.

What are the two basic factors that interact to produce skin color?

Circulatory supply and pigment concentration The two basic factors that interact to produce skin color are circulation and pigment concentration. Normal circulation to the skin will pigment the skin due to the presence of hemoglobin in the blood. Skin takes on a redder appearance as more blood flows into an area. Likewise, as more pigment concentrates in a region, skin takes on a darker appearance. The presence of carotene and melanin are not basic factors in producing skin color. Melanin production and skin thickness are not basic factors in producing skin color. Sunlight and ultraviolet radiation are not basic factors in producing skin color.

The term that refers to a bluish coloration of the skin is ___________.

Cyanosis During a sustained reduction in circulatory supply (decreased blood flow), the oxygen levels in the tissues decline. Under these conditions, hemoglobin releases oxygen and turns a much darker red. Seen from the surface, the skin takes on a bluish coloration called cyanosis. Keratinization is the normal process of accumulating keratin in the epidermis. Vitilgo results from loss of melanocytes, causing white patches on the skin. Jaundice results from accumulation of a breakdown product of bile, which causes a yellowish discoloration of the skin.

The reticular layer of the dermis is composed of what kind of tissue?

Dense irregular connective tissue The reticular layer of the dermis consists of an interwoven meshwork of dense irregular connective tissue, containing both collagen and elastic fibers. Bundles of collagen fibers extend superficially beyond the reticular layer and blend into those of the papillary layer. Besides the fibers, the dermis contains all the cells of connective tissue proper.

What are the two layers of the cutaneous membrane (skin)?

Dermis and epidermis Dermis and epidermis are the two layers of the skin. The epidermis is the most superficial layer and is composed of stratified squamous epithelium. This layer is continuously renewed and is one of the first major barriers protecting the body's interior. The dermis is under the epidermis and serves a supportive function. This layer is composed of areolar and connective tissue, which contains blood vessels and nerves.

Which of the following is not an effect of epidermal growth factor (EGF) on the epidermis? a. Stimulating the synthesis of melanin b. Stimulating division of cells in stratum basale c. Accelerating keratin production d. Stimulating repair of the epidermis after injury

EGF has multiple roles in the growth and functioning of the epidermis. It stimulates division of basal cells in the stratum basale and spinosum. It accelerates the production of keratin in keratinocytes. It stimulates epidermal repair after an injury. It also stimulates synthesis and secretion by epidermal glands. However, it is exposure to the sun's UV radiation and melanocyte-stimulating hormone (MSH) that stimulates the production of melanin.

Which structure is an accessory structure rather than part of the cutaneous membrane?

Exocrine glands The integumentary system has two major parts: the cutaneous membrane and the accessory structures. The cutaneous membrane has two components: the epidermis and the dermis. The dermis is composed of the papillary layer and the reticular layer. The accessory structures include hair follicles, exocrine glands, and nails.

Where is epidermal growth factor produced?

Glands of the duodenum Epidermal Growth Factor (EGF) is one of several growth factors produced by the body. It was named for its effects on the epidermis, but we now know it has widespread effects on epithelia throughout the body. EGF is produced by salivary glands and glands of the duodenum (the initial segment of the small intestine)

Which of the following layers is composed of adipose and areolar tissues and is the site where subcutaneous injections are given?

Hypodermis Hypodermis is the layer composed of adipose and areolar tissues and is the site where subcutaneous injections are given. This layer is also known as the superficial fascia. It has a limited number of capillaries and no vital organs, which is useful when administering drugs.

What is the subcutaneous layer that separates the integument from the deep fascia around other organs?

Hypodermis Hypodermis is the subcutaneous layer that separates the integument from the deep fascia around other organs. This layer contains adipose and areolar tissue, which makes it quite elastic. Since there are no vital organs in this area, it is also where subcutaneous injections are given. Dermis is the layer deep to the epidermis. Epidermis is the most superficial layer of the skin. Reticular layer of the dermis lies deep to the papillary layer.

How do third-degree burns differ from first- and second-degree burns?

In a third-degree burn, the epidermis, dermis, and hypodermis are destroyed. In a third-degree burn, the epidermis, dermis, and hypodermis are destroyed. This is the most damaging of all the burn categories because of the extensive tissue destruction. Third-degree burns frequently require skin grafts since stem cells for regrowth are destroyed because of this injury. If a large area of skin is lost as a result of a third-degree burn, the body's ability to regulate body temperature, water loss, and immune function could seriously be compromised. Third-degree burns may have no pain initially since sensory receptors are also destroyed. Fluid accumulates between the dermis and the epidermis in a second-degree burn, not a third-degree burn. A first-degree burn, not a third-degree burn, is restricted to the superficial layers of the skin.

Why is limited exposure to the UV light in sunlight beneficial?

It converts a steroid into vitamin D3. This steroid is a form of cholesterol that is present in skin. The conversion is made by epidermal cells in the stratum spinosum and stratum basale. By definition, vitamin D3 is also a hormone since it is made in the skin but has profound effects on parts of the body distant from where it is made in small doses.

What is the water-resistant, fibrous protein that fills the cells of the outer layers of the epidermis and helps slow dehydration?

Keratin Keratin is a tough, fibrous, water-resistant protein. As keratin fibers accumulate, the stratum corneum cells grow thinner and flatter, and their plasma membranes thicken and become less permeable. The dead cells in each layer of the stratum corneum remain tightly connected to each other, forming a water-resistant layer that helps prevent dehydration.

Which type of cell is the most abundant epithelial cell in the body and dominates the cellular composition of the epidermis?

Keratinocyte Keratinocytes dominate the cellular composition of the epidermis and are the most abundant epithelial cells in the body. These cells begin their life cycle in the basal layer. As they ascend toward the surface, keratinocytes begin to lose their organelles, until all that remains on the apical surface is a dead cell filled with keratin. These dead cells, due to their continued connection to other cells in this layer, form a protective layer. Dendritic cells are immune cells that make up part of the cell population in the epidermis. Melanocytes are present in the basal layer of the epidermis. Merkel cells are sensory receptors that detect pressure and touch.

A decrease in the number of __________ leads to increased damage and infection associated with age.

Langerhans cells A decrease in the number of Langerhans cells leads to increased damage and infection associated with age. Also known as dendritic cells, they have a branched morphology that extends throughout the epidermis. These cells protect the skin from microorganisms and also stimulate defenses against superficial skin cancers. Merkel cells are not immune cells but specialized touch receptors. A decrease in the number of melanocytes in the skin does not increase the incidence of infection. Nerve cells are not immune cells in the skin

The peptide that is secreted by the pituitary gland and increases the rate of melanin production is __________.

MSH The peptide that is secreted by the pituitary gland and increases the rate of melanin production is MSH. This peptide, melanocyte-stimulating hormone, will cause a darkening of the skin if overproduced by the pituitary. This darkening results from MSH causing melanocytes to produce more packets of melanin, which are distributed to the outlying keratinocytes. ATP is not a peptide but a nucleotide derivative. HDL is a lipoprotein, not a peptide. HGH is a hormone, not a peptide.

Why does a person's hair turn white or gray with age?

Melanocyte activity decreases. Hair follicles stop functioning or produce thinner, finer hairs. Melanocyte activity decreases and therefore melanin production decreases. With less pigment production and thinner hairs, the elderly person's hair becomes gray or white.

The stage of repair of a wound in which a fibroblast moves into the wound area is called the __________.

Migratory phase The scab temporarily restores the integrity of the epidermis and holds the edges of the wound together. The clot is a mass of fibrin fibers. This is the framework for repair. Division of fibroblasts and mesenchyme cells produce mobile cells that invade the deeper areas of the injury to begin reestablishing the dermis. This invasion constitutes the migratory phase.

What are the two layers of the dermis?

Papillary and reticular layers The two layers of the dermis are the papillary and reticular layers. The dermis lies deep to the epidermis and serves a supportive function. This layer of the integument contains blood vessels and nerves.

Sebaceous glands release which type of secretion?

Sebum Sebum is the secretion produced in sebaceous glands. Sebum is a mixture of fats, protein, and electrolytes. This mixture inhibits the growth of bacteria on the skin. This secretion also lubricates the hair and skin, which enables the epithelium and its barrier function to be maintained and preserved. It also prevents cracking of this layer, which would compromise its protective function and leave the body vulnerable to invasion from pathogens. Milk is the secretion produced in mammary glands. Cerumen, also known as earwax, is produced in ceruminous glands. Sensible perspiration, also known as sweat, is produced in eccrine sweat glands.

The secretion that lubricates the skin and inhibits growth of bacteria is called __________.

Sebum Sebum is the secretion that lubricates the skin and inhibits growth of bacteria. By way of this lubrication, sebum also helps enhance the skin's barrier function. Serum is plasma minus clotting factors. Lymph is fluid that circulates in the lymphatic vessels.

Excessive exposure of the skin to ultraviolet radiation may cause redness, edema, blisters, and pain. The presence of blisters characterizes the burn as __________.

Second degree The presence of blisters in a burn characterizes it as a second-degree burn. Blisters are fluid-filled spaces formed when the epidermis and dermis come apart. This is a more severe tissue disruption than that seen in a first-degree burn but is not as severe as the destruction seen in a third-degree burn. First-degree burns are characterized by redness, pain, and swelling but not blisters. Third-degree burns are very severe and are characterized by tissue destruction but not blisters.

An important function of the hypodermis is to __________.

Stabilize the position of the skin in relation to underlying tissues This supportive function is made possible because the hypodermis is composed of loose connective tissue.

In which layers of the epidermis do mitotic divisions occur?

Stratum basale and stratum spinosum The stratum basale and stratum spinosum are the layers where mitosis occurs. The stem cells from which all keratinocytes originate reside in the stratum basale. The daughter cells that are produced from these stem cells are pushed upward into the stratum spinosum. Some of these daughter cells continue to divide, so mitosis is seen in both these layers.

What is the most superficial layer of the epidermis?

Stratum corneum Stratum corneum is the most superficial layer of the epidermis. This layer is composed of stratified squamous epithelium, which is continuously renewing itself. The most basal layer, the stratum basale, contains stem cells, which are the source of cell growth. The epithelial cells in these layers are known as keratinocytes and are characterized by the protein keratin.

Which epidermal stratum is the most superficial and is composed of 15-30 layers of dead, keratinized cells that eventually are shed from its surface?

Stratum corneum The stratum corneum is the most superficial and is composed of 15-30 layers of dead, keratinized cells that eventually are shed from its surface. This stratified squamous epithelium functions as a protective barrier against the outside environment as well as water loss and mechanical trauma.

In thick skin, what is the thickest (most cell layers) stratum of the epidermis?

Stratum corneum The stratum corneum is the thickest layer as a result of the increased cell production. Thick skin is found on the palms of the hands and the soles of the feet. Note that the terms thick and thin refer to the relative thickness of the epidermis, not the cutaneous membrane. Pressure and "wear and tear" stimulate the cells in stratum basale to divide, rapidly producing more daughter cells.

The adipose tissue in the hypodermis performs a variety of functions. Which function does the adipose tissue not perform? a. Strengthening the hypodermis b. Energy reserve c. Insulation d. Shock absorption

The hypodermis consists of areolar tissue and adipose tissue. The subcutaneous fat of the hypodermis makes up 80 percent of all body fat. Thus it is an important energy reserve. This layer of fat has important insulating properties and helps reduce heat loss. It also acts as a shock absorber to cushion us against minor bumps. However, it does not have a lot of collagen fibers like the dermis, and so strength is not one of its properties.

Why are malignant melanomas extremely dangerous and life-threatening?

The melanocytes grow rapidly and metastasize through the lymphatic system. The melanocytes grow rapidly and metastasize through the lymphatic system and/or blood vessels. Melanocytes are epithelial cells, a cell type that by nature is regenerative. When growth control is lost, an especially fast-growing cancer develops. The cancer's potential for metastasis is also increased, which means melanoma cells can spread through the blood and lymphatic circulation early in the course of the disease. They can form tumors that interfere with circulation, but this is not the reason for their life-threatening nature. Metastasis is never restricted to the dermis and epidermis. They do develop in the germinative layer of the epidermis, but this is not the reason for their life-threatening nature.

Bone strength and density decrease as a person ages. There are multiple factors that can cause this. What change in the integumentary system can contribute to this?

Vitamin D3 production decreases. Vitamin D3 production declines. The liver ordinarily converts Vitamin D3 (cholecalciferol) into an intermediate used by the kidney to produce calcitriol. Calcitriol is essential for normal absorption of calcium and phosphorus in the small intestine. An inadequate supply of calcium and phosphorus leads to impaired bone maintenance and growth, leading to a loss of bone strength and density.

Sagging and wrinkling of the integument are due to __________.

a decrease in the elastic fibre network of the dermis Sagging and wrinkling of the integument are due to a decrease in the elastic fiber network of the dermis. This decrease lessens the ability of skin to return to its original texture and shape. Elastic fibers are the major factor that helps skin respond and return to a normal form after undergoing mechanical stresses. These elastic fibres have a springlike behaviour that is not seen in other connective tissue fibres such as collagen. The decline of germinative cell activity in the epidermis does not cause sagging and wrinkling of the dermis. A decrease in the vitamin D production of the integument does not cause sagging and wrinkling of the dermis. Deactivation of sweat glands does not cause sagging and wrinkling of the integument.

When scar tissue formation continues beyond the requirements of tissue repair, __________ is formed.

a keloid A keloid is formed when scar tissue formation continues beyond the requirements of tissue repair. This excess scar tissue takes the form of a raised area over the skin that is filled with disorganized collagen fibers. This tissue lacks the elasticity and pliability of the regular integument. Granulation tissue is not scar tissue. An ulcer is an area of deteriorated epithelium. A basal cell carcinoma is cancerous tissue.

A thick, raised area of scar tissue that grows into the tissue surrounding an injury site is called __________.

a keloid A thick, raised area of scar tissue that grows into the tissue surrounding an injury site is called a keloid. This raised area of tissue results from the overaccumulation of fibrotic tissue after an inflammatory response has failed to produce regeneration. In this case, fibrosis creates scar tissue as filler material to replace the area of previously functioning tissue. When this happens beyond the point of merely replacing the missing tissue, a raised area of scar tissue known as a keloid is created. Melanoma is a malignant skin cancer type. Warts are benign tumors in keratinocytes. Sebum is a secretion from sebaceous glands.

The hypodermis is useful for subcutaneous injection by hypodermic needle because it has __________.

a limited number of capillaries and no vital organs The hypodermis is useful for subcutaneous injection by hypodermic needle because it has a limited number of capillaries and no vital organs. Lamellar corpuscles are sensory receptors found in the dermis.

Which of the following factors does not increase the time needed for repair of an injury to the integument? a. A narrow slit-like wound b. Larger injured areas c. Infections d. A deep scrape

a. A narrow slit-like wound A narrow slit-like wound, like a paper cut or a surgical incision, will heal faster than a deep scrape or abrasion. This is probably because the edges of the wound stay closer together and are aligned. Infection is less likely and fluid loss is minimal. This makes the healing process quicker.

Which of the following statements describes the immediate response of the skin to an injury? a. Bleeding occurs, and mast cells trigger an inflammatory response. b. A scab forms. c. Fibroblasts in the dermis create scar tissue. d. The epidermal cells are replaced.

a. Bleeding occurs, and mast cells trigger an inflammatory response. Bleeding occurs, and mast cells trigger an inflammatory response would describe an immediate response of the skin to injury. Bleeding occurs any time blood vessels are damaged. Blood clotting would soon follow to stem any excessive blood loss. Mast cells, on the other hand, would release histamine into the area to facilitate more blood flow into the damaged tissue. This would bring on many of the classic signs of inflammation, including redness, heat, and swelling. The epidermal cells are replaced much later in the healing process and after the inflammatory response. Fibroblasts in the dermis create scar tissue much later. A scab forms after the initial inflammatory response has occurred.

What change in the integument causes older people to be more sensitive to hot temperatures? a. Decreased glandular activity b. Thinning of the epithelium c. Thinning of the dermis d. Lightening skin colour

a. Decreased glandular activity Older people are more sensitive to hot temperatures because glandular activity declines. Merocrine sweat glands are less active. With impaired perspiration, older people cannot lose heat as fast as a younger person. So, the elderly are at a greater risk of overheating.

Full-thickness or third-degree burns are the most serious. Which of the following is not a major concern in the treatment and repair of these types of burns? a. Excessive blood loss b. Replacement of fluids and electrolytes c. Preventing infection d. Temperature regulation

a. Excessive blood loss Even though there is fluid loss, excessive bleeding does not occur. Considering the functions of the skin gives us the answer to the problem of third-degree burns. Areas of full thickness burns lose their effectiveness as a barrier to fluid and electrolyte loss. The dampness of the epidermal area, resulting from fluid loss, encourages bacterial growth. Thus the barrier to prevent infection is removed. Increased fluid loss means increased evaporative cooling, making temperature regulation more difficult.

Which of the following does the integument not synthesize or produce? a. Lipids b. Keratin c. Vitamin D d. Melanin

a. Lipids There is storage, sometimes abundant, of lipids in the adipocytes of the dermis and in the adipose tissue of the hypodermis. However, synthesis of lipids does not occur in the integument. Storage of lipids occurs, but not synthesis.

Which of the following is a dark brown, yellow-brown, or black pigment produced by pigment cells in the stratum basale? a. Melanin b. Lentigo c. Keratin d. Carotene

a. Melanin Melanin is the dark brown pigment that is produced in the stratum basale. This pigment is produced by melanocytes, which in turn deliver this pigment in packages to keratinocytes. Melanin acts to protect the nuclei of keratinocytes from the potentially harmful effects of UV radiation. Carotene is an orange pigment made in plants. Keratin is a tough, fibrous protein. Lentigo describes an area of abnormal pigmentation.

Which of the following is NOT an effect of aging on the integumentary system? a. Melanocyte activity increases, darkening the skin. b. Glandular activity declines. c. Dendritic cells (and immunity) decrease. d. The epidermis and dermis thin.

a. Melanocyte activity increases, darkening the skin. Melanocyte activity decreases, darkening the skin is NOT an effect of aging in the integumentary system. The epidermis and dermis thin as we age. Dendritic cells (and immunity) decrease with age. Glandular activity declines with age.

The integumentary system has a protective function. From which of the following does the skin not protect us? a. Pressure and pain stimuli b. Fluid loss c. Ultraviolet radiation d. Large temperature changes

a. Pressure and pain stimuli No other organ is as accessible as the integumentary system. We are exposed constantly to external stimuli. Sensory receptors in the skin monitor touch, pressure, temperature, and pain. The integumentary system does not shield us from those stimuli but constantly detects and responds to them.

What structure of the hair or hair follicle lets you feel your hair being blown out of place by the wind? a. Root hair plexus b. Hair bulb c. Hair matrix d. Hair papilla

a. Root hair plexus Deep to the epidermis, each follicle is wrapped in a dense connective tissue sheath. A root hair plexus of sensory nerves surrounds the base of each hair follicle. As a result, you feel the movement of the shaft of even a single hair. This sensitivity provides a warning system that may help prevent injury. But it also tells you when your hair is out of place. The hair bulb is the bulging base of a hair follicle, and is where hair production begins. The hair matrix is the layer of epithelial cells that produces the hair. The hair papilla is connective tissue containing capillaries and nerves and is surrounded by the hair bulb.

Which gland produces an oily secretion that lubricates the hair and skin? a. Sebaceous gland b. Ceruminous gland c. Eccrine sweat gland d. Apocrine sweat gland

a. Sebaceous gland The sebaceous gland produces an oily secretion that lubricates the hair and skin. This oily secretion has a protective function that maintains the epithelial barrier and keeps it from drying out. Apocrine sweat glands produce a thick secretion in the armpits and pubic areas. Eccrine sweat glands produce a watery secretion in the skin that helps thermoregulation. Ceruminous glands produce a waxy secretion in the ear canals.

Which of the following functions is NOT associated with the skin? a. Synthesis of B vitamins b. Detection of sensory information c. Excretions of salts, organic wastes, and water d. Maintenance of normal body temperatures

a. Synthesis of B vitamins Synthesis of B vitamins is a function of the large intestine, not the skin. The Major vitamin made in the skin is vitamin D3. Although classified as a vitamin, it is also a hormone since it is made in one part of the body and is transported through the bloodstream to distant tissues, where it exerts effects. The synthesis of D3 is accomplished through the exposure of skin to sunlight, which acts on a cholesterol derivative to create vitamin D3. Maintenance of normal body temperatures is a major function of the skin. Excretions of salts, organic wastes, and water is a major function of the skin. Detection of sensory information is a major function of the skin.

Which of the following are benign tumours that occur in the skin? a. Warts b. Contusions c. Hives d. Keloids

a. Warts Warts are benign tumors in the skin. They usually result from a localized viral infection that infects a keratinocyte and alters its DNA, causing a mutation in one of the genomic sequences regulating cell growth. Once this mutation occurs in a growth regulatory region of the DNA, the cell becomes abnormal. Since these abnormal cells grow faster than the surrounding normal cells, they also accumulate greater numbers in the area, which results in a raised area of tissue known as a wart. Keloids are accumulations of scar tissue and are not benign tumors. Hives are raised areas that result from acute inflammation. Contusions are regions of swelling resulting from mechanical trauma.

What is the first step of integument repair following an injury? a. Bleeding and inflammation b. Formation of scar tissue to elevate the epithelial tissue c. Growth of epidermal cells under the scab d. Scab formation

a. bleeding and inflammation Bleeding and inflammation are the first steps of integument repair following an injury. Inflammation is the body's natural response to tissue injury, and many of the events that follow inflammation are related to blood flow to the area. Bleeding is also an immediate event after an injury if blood vessels were damaged. During this initial series of events, blood loss is stopped by clotting while blood flow to the injured site is enhanced in order to begin the repair process. Scab formation happens after the initial steps of repair. Growth of epidermal cells under the scab happens after the first step of repair. Formation of scar tissue to elevate the epithelial tissue is one of the last steps in the repair process.

Which of the following would result in the loss of large portions of skin and lead to increased risk of infection and fluid loss? a. burns b. cyanosis c. dermatitis d. skin cancers

a. burns Burns result in the loss of large portions of skin and lead to increased risk of infection and fluid loss. Skin has a protective barrier function that shields the body against pathogens. This barrier also helps maintain body temperature and water content. When this barrier is lost, the body is vulnerable to infection as well as to dysfunction in temperature homeostasis. Skin cancer is the result of abnormal cell growth. Dermatitis is an inflammation of the skin. Cyanosis results from a lack of oxygen in tissues.

Which of the following is not an accessory structure in the integumentary system? a. Epidermis b. Glands c. Hair d. Nails

a. epidermis Epidermis is not an accessory organ of the integumentary system. Epidermis is the top layer of skin, which is formed from stratified squamous epithelium. This layer of skin forms a mechanical barrier against friction as well as pathogens in the environment. This top layer is also the source of vitamin D production in the body as well as the protective pigment melanin.

The hardness of the nails protects the dorsal surfaces of the fingers and toes. What substance causes the hardness? a. keratin b. collagen fibers c. elastic fibers d. cuticle

a. keratin The body of the nail consists of dead tightly compressed cells packed with keratin. The body of the nail covers an area of epidermis, called the nail bed, on the dorsal portion of the digit. This body of the nail with its keratinized cells protects the distal portion of the fingers and toes.

When the body temperature becomes abnormally high, thermoregulatory homeostasis is maintained by __________.

an increase in sweat gland activity and an increase in blood flow to the skin When the body temperature becomes abnormally high, thermoregulatory homeostasis is maintained by an increase in sweat gland activity and an increase in blood flow to the skin. A decrease in blood flow to the skin and a decrease in sweat gland activity would cause a further rise in body temperature and movement away from homeostasis. An increase in blood flow to the skin and a decrease in sweat gland activity would cause a further rise in body temperature and movement away from homeostasis. An increase in sweat gland activity and a decrease in blood flow to the skin would cause a further rise in body temperature and movement away from homeostasis.

What are the primary tissues comprising the hypodermis?

areolar and adipose The primary tissues comprising the hypodermis are areolar and adipose tissues. Areolar tissue is a type of loose connective tissue that has a supportive function. Adipose tissue is a specialized form of connective tissue that stores energy. Adipocytes in this tissue store energy in the form of triglycerides. These lipids are hydrolyzed to form fatty acids that are used to form ATP in mitochondria.

Where can you find an apocrine sweat gland?

armpits, nipples, and pubic region The armpits, nipples, and pubic region are areas where you can find apocrine sweat glands. These sweat glands produce a slightly more protein-rich fluid compared to the fluid produced by the eccrine sweat glands. This fluid is secreted in the hair follicle areas and is subject to bacterial digestion. This bacterial activity will also make the secretion odiferous. These sweat glands begin their activity at puberty. The palms of the hands and soles of the feet are regions where you find eccrine sweat glands. The top of the head contains eccrine sweat glands. Most of the body's surface contains eccrine sweat glands.

Special smooth muscles in the that produce 'goose bumps' when they contract are called __________.

arrector pili Special smooth muscles in the dermis that produce 'goose bumps' when they contract are called arrector pili. These muscles are involuntary and under the control of the autonomic nervous system. Emotions such as fear and rage, which initiate sympathetic nervous system activation, will cause these muscles to contract. Their contraction forces hairs to stand erect. Tissue papillae are components of integument, not smooth muscle. Root sheaths are components of hair, not smooth muscle. Cuticular papillae are not smooth muscles.

Hair turns gray or white because of __________.

decreased melanocyte activity Hair turns gray or white because of decreased melanocyte activity. This decrease in melanocyte activity decreases the delivery of the pigment melanin to keratinocytes in the hair matrix. This decrease in delivery in turn causes less pigment in the hair itself, which results in hair turning more gray or white as time goes on.

Which gland functions in thermoregulation?

eccrine sweat gland Eccrine sweat glands produce a watery secretion that functions in thermoregulation. This aqueous secretion helps transfer heat to the surface of the body, where it can evaporate. This function is vital in helping maintain temperature homeostasis of the body. Sebaceous glands produce an oily secretion that lubricates hair and skin. Ceruminous glands produce a waxy secretion that lines the ear canals. Mammary glands produce an apocrine secretion that is used as food for newborns.

The tissue that overlays the exposed nail is the __________.

eponychium or cuticle A portion of the stratum corneum extends over the exposed nail, forming the eponychium or cuticle. Nail production takes place at the nail root, an epidermal fold not visible from the surface. This area has dividing cells, like the stratum basale cells of the skin, which produce the cells of the nail pushing the nail distally.

The term for the redness that develops with a first-degree burn is __________.

erythema Only the surface of the epidermis is affected by a first-degree burn. The heat trauma causes increased blood flow to this injured area. The redness, a sign called erythema, results from inflammation of the heat-damaged tissues.

Ceruminous glands are modified sweat glands located in the __________.

external auditory canal Ceruminous glands are modified sweat glands located in the external auditory canal. These glands produce a waxy lipid known as cerumen, which has protective functions in the external auditory canal and helps to capture dust and debris that might become trapped in this passageway. This substance also helps lubricate and moisten the external auditory canal, which helps maintain its barrier as well.

Accessory structures of the skin include the __________.

hair follicles and the sebaceous and sweat glands Accessory structures of the skin include the sebaceous glands, sweat glands, and hair follicles. These structures are distributed throughout the surface of the skin but originate in the dermal layer of the cutaneous membrane. Sebaceous glands produce an oily secretion that protects and lubricates skin and hair. Sweat glands produce a watery secretion that facilitates thermoregulation. Hair follicles aid the sense of touch and also serve as a source of stem cells in the integument.

Nail production begins at the __________.

nail root Nail production takes place at the nail root, an epidermal fold not visible from the surface.

The stage of repair of deep skin injury in which epidermal cells migrate under the scab is called the __________.

proliferation phase Over time, deeper portions of the original clot dissolve and the number of capillaries that grew into the wound during the migratory phase declines. Epidermal cells from the edge of the wound divide and migrate under the scab over the collagen fiber meshwork produced by the fibroblasts. This repairing of the epidermis is the proliferation phase

The practical limit to the healing process of the skin is the formation of inflexible, fibrous, noncellular __________.

scar tissue The practical limit to the healing process of the skin is the formation of inflexible, fibrous, noncellular scar tissue. Scars are also known as fibrotic tissue, which is a general tissue replacement that occurs when regeneration of the original tissue is not possible. Scar tissue acts as a filler material that lacks the function of the original tissue.

Psoriasis is a skin disorder in which there is abnormally increased mitotic activity in the __________.

stratum basale Psoriasis is a skin disorder in which there is abnormally increased mitotic activity in the stratum basale. This activity is rooted in abnormal stem cell activity in the stratum basale. This is a chronic disease that results in scaly patches of skin that accumulate on the surface. Stratum lucidum is not mitotically active. Stratum spinosum has mitotic activity but is not the source of an abnormal increase in mitosis. Stratum corneum is not mitotically active.

What is the correct order of strata from the basement membrane to the free surface of the epidermis?

stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum The deepest layer of the epidermis is the stratum basale. Hemidesmosomes anchor it to the basement membrane. Stratum basale cells divide and the daughter cells are pushed toward the surface, forming the stratum spinosum. As cell division continues, the stratum spinosum cells are pushed toward the surface forming the stratum granulosum. This layer begins the formation of keratin. They are also pushed further outward away from the dermis. This new layer is the stratum lucidum. Finally, the stratum lucidum cells are pushed to the surface. The stratum corneum is the outermost or surface layer.

Which epidermal layer is found only in thick skin?

stratum lucidum Stratum lucidum is found only in thick skin. This layer is prominent in the palms of the hand and the soles of the feet. The keratinocytes in this layer are also characterized by the production of the protein eleidin in addition to keratin. Stratum corneum is the most superficial layer of the epidermis. Stratum granulosum is found in all regions of skin. Stratum basale is found in all regions of skin.

The type of hairs that are found on the head of an adult and are actively growing are __________.

terminal hairs The heavily pigmented hairs on the head, eyebrows, and eyelashes are terminal hairs. Hairs that have stopped growing are club hairs and will fall out. Very fine unpigmented hair of an embryo is lanugo. Very fine hair over most of the body of an adult is vellus hair.

Differences in skin color among individuals are the result of __________.

the different levels of melanin synthesis Differences in skin color among individuals are the result of the different levels of melanin synthesis. Melanocytes are the source of the pigment melanin. This dark brown pigment, in addition to giving skin color, also has a protective function. When this pigment accumulates inside keratinocytes, it protects the nucleus and DNA inside from damage due to UV radiation. Differences in skin color do not reflect different numbers of melanocytes. Differences in the number of sebaceous glands do not result in differences in skin color. Differences in the thickness of skin do not result in differences in skin color.

Sensible perspiration released by the eccrine sweat glands serves __________.

to cool the surface of the skin, to reduce body temperature, and to dilute harmful chemicals The ability of the eccrine sweat glands to secrete a watery fluid helps the body rid itself of excess heat by evaporation. This facilitates temperature homeostasis and enables the body to maintain temperature in a stable range. This fluid also dilutes harmful chemicals and neutralizes pathogens by antimicrobial activity.

The primary benefit of having fingernails and toenails is __________.

to protect the dorsal surface of the tips of the fingers and toes The body of the nail covers an area of epidermis on the distal end of the digit. It is recessed deep to the level of the surrounding epithelium. This arrangement protects the dorsal surface of the tips of the fingers and toes. Fingerprints are on the opposite side of the finger from the nails. A form of vitamin D is produced by the s. basale and the s. spinosum, not the fingernails.

What is the natural factor responsible for varying shades of hair color?

type of melanin present The type of melanin present is the major factor in determining shades of hair color. The more reddish form of melanin, known as pheomelanin, is one variation, and it lightens hair color. The darker version is known as eumelanin. Varying amounts of each form of melanin produce the various shades of hair color. The body does not produce carotene; this is produced in plants. The number of melanocytes is not the major factor in determining hair color.