Anatomy Chapter 5 Review Questions

Compare thin skin with thick skin.

Thin skin and thick skin refer to the relative thickness of the epidermis, not the cutaneous membrane. Thin skin covers most of the body surface and contains four strata (layers) of cells. Thick skin covers the palms of the hand and soles of the feet and contains five strata of cells.

Using the rule of nines, the right leg is 18% of surface area, the right arm is 9% of surface area, and the back of the trunk is 18% of surface area. Adding these values gives a total surface burn area of 45%.

A 32-year-old woman is admitted to the hospital with third-degree burns on her entire right leg, entire right arm, and the back of her trunk. Estimate the percentage of her body surface area affected by these burns.

Dandruff consists of cells from the stratum corneum.

Dandruff is caused by excessive shedding of cells from the outer layer of skin on the scalp. So, dandruff is composed of cells from which epidermal layer?

Deodorants are used to mask the odor of apocrine sweat gland secretions.

Deodorants are used to make the effects of secretions from which type of skin gland?

A typical hair is a keratinous strand produced by basal cells within a hair follicle.

Describe a typical strand of hair.

Granulation tissue is the combination of blood clots, fibroblasts, and the extensive network of capillaries in healing tissue.

Describe granulation tissue.

Hair follicles transition between an active phase of continuous hair growth; regression; a resting phase, when the hair becomes a club hair; and reactivation of hair growth and shedding of club hair.

Describe the four phases of the hair growth cycle.

The exocrine glands in the skin are sebaceous and sweat glands. Together, they assist in thermoregulation, excrete wastes, and lubricate hairs and the epidermis.

Identify and describe the general functions of the exocrine glands found in the skin.

The first step in tissue repair is inflammation. Inflammation produces swelling, redness, heat, and pain.

Identify the first step in skin repair.

The five layers of the epidermis from deep to superficial are the stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum.

Identify the five layers of the epidermis (from superficial to deep).

The major functions of the integumentary system are to protect underlying tissues and organs, excrete wastes by integumentary glands, maintain body temperature, produce melanin and keratin, synthesize vitamin D, store lipids, and detect touch, pressure, pain, and temperature.

Identify the major functions of the integumentary system.

The two major components of the cutaneous membrane are the epidermis and the dermis. The subcutaneous layer (hypodermis) is not part of the integument.

Identify the two major components of the cutaneous membrane.

The hormone cholecalciferol (vitamin D3) is needed to form strong bones teeth. When the body surface is covered, UV radiation cannot reach the skin to stimulate cholecalciferol (vitamin D3) production, so bones can become fragile.

In some cultures, females must be covered from head to toe when they go outdoors. Explain why these women are at increased risk of developing bone problems later in life.

Hormones that are necessary for maintaining healthy skin include growth hormone, sex hormones, growth factors (including epidermal growth factor [EGF]), glucocorticoids (steroid hormones), and thyroid hormones.

List some hormones that are necessary for maintaining a healthy integument.

The two pigments in the epidermis are carotene (an orange-yellow pigment) and melanin (a brown, yellow-brown, or black pigment).

Name the two pigments contained in the epidermis.

Contractile myoepithelial cells aid merocrine secretion discharge. They are found in apocrine and eccrine sweat glands, mammary glands, lacrimal glands, and salivary glands.

Name the type of cell that assists the discharge of merocrine secretions, and list the glands in which such cells are present.

Such a cut would cross the tension lines at a right angle, so a greater, rather than lesser, amount of scarring would be predicted.

Predict the degree of scarring after the healing of a horizontal cut on the forehead just above the eyebrow.

Epidermal derivatives are accessory structures that originate from the epidermis during embryonic development. They include hair follicles, sebaceous and sweat glands, and nails.

What are epidermal derivatives?

When arretor pili muscles contract, they pull the hair follicle erect. The overall effect is known as goose bumps.

What happens when an arrector pili muscle contracts?

Sweat glands and sebaceous glands are the exocrine glands in the integument.

Which exocrine glands are in the integument?

Third-degree burns often require skin grafting because the tissue damage is so great that the tissue cannot repair itself.

Which type of burn usually requires skin grafting? Why?

The dermis is made up of two layers of connective tissue: a papillary layer and a reticular layer. The superficial papillary layer consists of areolar tissue containing capillaries, lymphatic vessels, and sensory neurons that supply the surface of the skin. The deeper reticular layers consists of dense irregular connective tissue containing collagen and elastic fibers.

Describe the layers of the dermis.

Sebum is secreted by holocrine secretion. Sebum lubricates and protects the keratin of the hair shaft, lubricates and conditions the surrounding skin, and inhibits the growth of bacteria.

Describe the secretory method and functions of sebum.

In an autograft, the patient's undamaged skin is used as a graft source. An allograft uses skin from a donor, and a xenograft uses skin from an animal, such as a pig. Autografts are best because they are not rejected by the patient's immune system.

Describe the three types of skin grafts. Which one is best? Why?

A first-degree burn affects only the surface of the skin. This would include most sunburns. A second-degree burn damages the entire epidermis and perhaps some of the dermis. Although blistering occurs, accessory structures such as hair follicles and glands are generally not affected. Third-degree burns, also called full-thickness burns, destroy the epidermis and dermis and extend into the subcutaneous layer (hypodermis).

Distinguish among a first-degree, second-degree, and third-degree burn.

In the presence of UV radiation in sunlight, epidermal cells in the stratum spinosum and stratum basale convert a cholesterol-related steroid into cholecalciferol, also known as vitamin D3.

Explain the relationship between sunlight exposure and vitamin D3.

The child probably has a fondness for vegetables, such as carrots, squash, and sweet potatoes, which have a high amount of carotene, a yellow-orange pigment. If a child eats large amounts of food containing carotene, the pigment is stored in the skin, turning the skin a yellow-orange color.

Explain why a healthy 6-month-old might have yellow-orange skin.

A splinter that penetrates to the third epidermal layer of the palm is lodged in the stratum granulosum.

A splinter that penetrates to the third layer of the epidermis of the palm is lodged in which layer?

Skin can regenerate effectively even after undergoing considerable damage because stem cells persist in both the epithelial and connective tissue components of the skin. In response to injury, cells of the stratum basale replace epithelial cells, and mesenchymal cells replace lost dermal cells.

Why can skin regenerate effectively even after considerable damage?

As a person ages, the blood supply to the dermis decreases, and the eccrine sweat glands becomes less active. Both changes make it more difficult for older people to cool themselves in hot weather.

Why do people tolerate summer heat less well and become more susceptible to heat-related illness when they become older?

Exposure to sunlight or sunlamps darkens skin because the ultraviolet radiation they emit stimulates melanocytes in the epidermis to synthesize the pigment melanin.

Why does exposure to sunlight or sunlamps darken skin?

With advancing age, melanocyte activity decreases, leading to white or gray hair.

Why does hair turn white or gray with age?

When the skin gets warm, arriving oxygenated blood is diverted to the superficial dermis (papillary layer) to eliminate heat. The oxygenated blood imparts a reddish coloration to the light skin.

Why does the skin of a light-skinned person appear red during exercise in hot weather?

Cancerous basal cells rarely become malignant and metastasize, or spread, into other tissues throughout the body, as do melanoma cancer cells. Malignant melanoma is extremely dangerous because the cancerous melanocytes spread throughout the lymphatic system.

Why is basal cell carcinoma considered less dangerous than malignant melanoma?

Pulling a hair is painful because its root is attached deep within the hair follicle, the base of which is surrounded by a root hair plexus consisting of sensory nerves. Cutting a hair is painless because a hair shaft contains no sensory nerves.

Why is pulling a hair painful, yet cutting a hair is not?