Chapter 5

Front 1

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

Back 1

The layers of the epidermis are the stratum basale, stratum spinosum, stratum granulosum, stratum lucidem, and stratum corneum.

Front 2

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

Back 2

Dandruff consists of cells from the stratum corneum.

Front 3

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

Back 3

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

Front 4

Name the two pigments contained in the epidermis.

Back 4

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

Front 5

Why does exposure to sunlight or sunlamps darken skin?

Back 5

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

Front 6

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

Back 6

When skin gets warm, arriving oxgenated blood is diverted to the superficial dermis for the purpose of eliminating heat. The oxygenated blood imparts a reddish coloration to the skin.

Front 7

Describe the location of the dermis.

Back 7

The dermis ( a connective tissue layer) lies between the epidermis and the hypodermis.

Front 8

Where are the capillaries and sensory neurons that supply the epidermis located?

Back 8

The capillaries and sensory neuronsthat supply the epidermis are located in the papillary layer of the dermis.

Front 9

What accounts for the ability of the dermis to undergo repeated stretching?

Back 9

The pressence of elastic fibers allows the dermis to undergo repeated cycles of stretching and recoil (returning to its original shape).

Front 10

Describe a typical strand of hair.

Back 10

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

Front 11

What happens when an arrector pili muscle contracts?

Back 11

When an arrector pili muscle contracts, it pulls the hair follicle erect, depressing the area at the base of the hair and making the surrounding skin appear higher. The overall effect is known as "goose bumps" or "chicken skin".

Front 12

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

Back 12

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.

Front 13

Identify two types of exocrine glands found in the skin.

Back 13

Two types of exocrine glands found in the skin are sebaceous (oil) glands and sweat glands.

Front 14

What are the functioins of sebaceous secretions?

Back 14

Sebaceous secretions (sebum) lubricate and protect thekeratin of the hair shaft, lubricate and condition the surrounding skin, and inhibit the growth of bacteria.

Front 15

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

Back 15

Deodorants are used to mask the odor of apocrine sweat gland secretions, which contain several kinds of organic compounds. Some of these compounds have an odor when metabolized by skin bacteria. Apocrine sweat glands enlarge and increase secretory activity in response to the increase in sex hormones that occur at puberty.

Front 16

Identify some common effects of the aging process on skin.

Back 16

Common effects of the aging process on the skin include epidermal thinning due to a decline in germinative cell activity; a decrease in melanocyte abundance; a reduction in sebaceous gland secretion; a decline in dendritic cell numbers; a reduction in vitamin D3 production; a decline in glandular activity; the stoppage of hair follicle functioning; and a slowing of the pace of the skin repair.

Front 17

Why does hair turn white or gray with age?

Back 17

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

Front 18

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

Back 18

As a person ages, the blood supply to the dermis decreases, and merocrine sweat glands become less active. Both changes make it more difficult for the elderly to coll themselves in hot weather.

Front 19

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

Back 19

Some hormones that are necessary for maintaining healthy skin are growth hormones, sex hormones, growth factors (including epidermal growth factor), steroid hormones, and thyroid hormones.

Front 20

Explain the relationship between sunlight exposure and vitamin D3.

Back 20

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

Front 21

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.

Back 21

The hormones Cholecalciferol (vitamin D3) is needed to form strong bones and teeth. When the body surface is covered, ultraviolet radiation cannot reach the skin to stimulate cholecalciferol (vitamin D3) production, so fragile bones can develop.

Front 22

Identify the first step in the repair of tissue.

Back 22

The first step in the repair of tissue is inflammation.

Front 23

Describe granulation tissue.

Back 23

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

Front 24

Why can skin regenerate effectively even after considerable damage?

Back 24

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

Front 25

Define hyponychium.

Back 25

The hyponychium is the thickened stratum corneum underlyng the free edge of a nail.

Front 26

Describe a typical fingernail.

Back 26

A fingernail is a keratinous structure that is produced by epithelial cells of the nail root and protects the underlying fingertip. Structures of the nail include a distal free edge, lateral nail fold, lunula, proximal nail fold, eponychium, nail root, nail body, and hyponchium.

Front 27

Where does nail production occur

Back 27

Nail production occurs at the nail root, an epidermal fold that is not visible from the surface.