Identify the layers of the epidermis
The layers of the epidermis are the stratum germinativum, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum.
Dandruff is caused by excessive shedding of cells from the outer layer of skin in the scalp. Thus, dandruff is composed of cells from which epidermal layer?
Dandruff consists of cells from the stratum corneum.
A splinter that penetrates to the third layer of the epidermis of the palm is lodged in which layer?
This splinter is lodged in the stratum granulosum.
Why does swimming in fresh water for an extended period of time cause epidermal swelling?
Fresh water is hypotonic with respect to skin cells, so water moves into the cells by osmosis, causing them to swell.
Some criminals sand the tips of their fingers so as not to leave recognizable fingerprints. Would this practice permanently remove fingerprints? Why or why not?
Sanding will not permanently remove the fingerprints. The ridges of the fingerprints are formed in layers of the skin that are constantly regenerated, so these ridges will eventually reappear. The pattern of the ridges is not determined by the arrangement of tissue in the dermis, which is not affected by sanding.
Name two pigments contained in the epidermis.
The two pigments are carotene, an orange-yellow pigment, and melanin, a brown, yellow-grown or black pigment.
Why does exposure to sunlight or sunlamps darken skin?
When exposed to the ultraviolet radiation in sunlight or sunlamps, melanocytes in the epidermis and dermis synthesize the pigment melanin, darkening the skin.
Why does the skin of a fair-skinned person appear red during exercise in hot weather?
When skin gets warm, arriving oxygenated blood is diverted to the superficial dermis for the purpose of eliminating heat. The oxygenated blood imparts a reddish coloration to the skin.
Explain the relationship between sunlight exposure and vitamin D3 synthesis.
In the presence of ultraviolet radiation in sunlight, epidermal cells in the stratum spinosum and stratum germinativum convert a cholesterol-related steroid into cholecalciferol, also known as vitamin D3.
In some cultures, women must be covered completely, expect for their eyes, when they go outside. Explain why these women may develop bone problem later in life.
The hormone cholecalciferol (vitamin D3) is needed to form strong bones and teeth. When the body surface is covered, UV light cannot penetrate to the blood in the skin to begin vitamin D3 production, resulting in fragile bones.
Name the sources of epidermal growth factor in the body.
Salivary glands and duodenal glands produce epidermal growth factor (EGF).
Identify some roles of epidermal growth factor pertaining to the epidermis
EGF promotes the divisions of germinative cells in the stratum germinativum and stratum spinosum, accelerates the production of keratin in differentiating keratinocytes, stimulates epidermal development and epidermal repair after injury, and stimulates synthetic activity and secretion by epithelial glands.
Describe the location of the dermis.
The dermis (a connective tissue layer) lies between the epidermis and the hypodermis.
Where are the capillaries and sensory neurons that supply the epidermis located?
The capillaries and sensory neurons that supply the epidermis are located in the papillary layer of the dermis.
What accounts for the ability of the dermis to undergo repeated stretching?
The presence of elastic fibers and the resilience of skin turgor allow the dermis to undergo repeated cycles of stretching and recoil (returning to its original shape).
List two terms for the tissue that connects the dermis to underlying tissues
The tissue that connects the dermis to the underlying tissues is the hypodermis or subcutaneous layer.
Describe the hypodermis
The hypodermis is a layer of loose connective tissue below the dermis; it is also called the subcutaneous layer or superficial fascia. It is not considered a part of the integument, but it is important in stabilizing the position of the skin in relation to underlying tissues.
Identify several functions of subcutaneous fat.
Subcutaneous fat provides insulation to help reduce heat loss, serves as an energy reserve, and acts as a shock absorber to the body.
Describe a typical strand of hair
A typical hair is a keratinous strand produced by epithelial cells of the hair follicle.
What happens when the arrector pili muscle contracts?
The contraction of the arrector pili muscle pulls the hair follicle erect, depressing the area at the base of the hair and making the surround skin appear higher. The result is known as "goose bumps".
Once a burn on the forearm that destroys the epidermis and extensive areas of the deep dermis heals, will hair grow again in affected area.
Even though hair is a derivative of the epidermis, the follicles are in the dermis. Where the epidermis and deep dermis are destroyed, new hair will not grow.
Identify two types of exocrine glands found in the skin
Two types of exocrine glands found in the skin are the sebaceous (oil) glands and sweat glands.
What are the functions of sebaceous secretions
Sebaceous secretions (called sebum) lubricate and protect the keratin of the hair shaft, lubricate and condition the surrounding skin, and inhibit the growth of bacteria.
Deodorants are used to mask the effects of secretions from which type of skin gland
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 order, and others produce an odor when metabolized by skin bacteria.
Which type of skin gland is most affected by the hormonal changes that occur during puberty?
Apocrine sweat glands enlarge and increase secretory activity in response to the increase in sex hormones that occurs at puberty.
Describe a typical fingernail.
A fingernail is a keratinous structure produced by epithelial cells of the nail root that protects the fingertip.
What term is used to describe the thickened stratum corneum underlying the free edge of a nail?
The area of thickened stratum corneum under the free edge of a nail is called the hyponychium.
Where does nail growth occur?
Nail growth occurs at the nail root, an epidermal fold that is not visible from the surface.
What term describe the combination of fibrin clots, fibroblasts, and the extensive network of capillaries in healing tissue?
The combination of fibrin cloths, fibroblasts, and the extensive network of capillaries in the tissue that is healing is called the granulation tissue.
Why can skin regenerate effectively even after considerable damage?
Skin can regenerate effectively because stem cells persist in both the epithelial and the connective tissue components of skin. When injury occurs, cells of the stratum germinativum replace epithelial cells while mesenchymal cells replace cells lost from the dermis.
Older individuals do not tolerate the summer heat as well as they did when they were young, and they are more prone to heat-related illness. What accounts for these changes?
As a person ages, the blood supply to the dermis decreases and merocrine sweat glands become less active. These changes make it more difficult for the elderly to cool themselves in hot weather.
Why does hair turn white or gray with age?
With advancing age, melanocyte activity decreases, leading to gray or white hair.
Identify the common purpose that the integumentary system serves for all body systems.
The integumentary system provides the whole body, and thus all its system, mechanical protection against environmental hazards.