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18) The reason the hypodermis acts as a shock absorber is that ________.

the major part of its makeup is adipose, which serves as an effective shock absorber

20) Keratinocytes are an important epidermal cell because they ________.

produce a fibrous protein that gives the skin much of its protective properties

Melanocytes and keratinocytes work together in protecting the skin from UV damage when
keratinocytes ________.

accumulate the melanin granules on their superficial portion, forming a UV-blocking pigment
layer

The epidermis consists of five layers of cells, each layer with a distinct role to play in the
health, well-being, and functioning of the skin. Which of the layers is responsible for
cell division and replacement?

stratum basale

The integumentary system is protected by the action of cells that arise from bone marrow and
migrate to the epidermis. Which of the following cells serve this function?

macrophages called epidermal dendritic cells

Water loss through the epidermis could cause a serious threat to health and well-being.
Which of the following protects us against excessive water loss through the skin?

Lamellated granules of the cells of the stratum granulosum, a glycolipid that is secreted into
extracellular spaces.

The dermis is a strong, flexible connective tissue layer. Which of the following cell types are
likely to be found in the dermis?

fibroblasts, macrophages, and mast cells

The dermis has two major layers; which of the following constitutes 80% of the dermis and
is responsible for the tension lines in the skin?

the reticular layer

Despite its apparent durability, the dermis is subject to tearing. How might a person know
that the dermis has been stretched and/or torn?

The appearance of visible, silvery-white scars is an indication of stretching of the dermis.

The papillary layer of the dermis is connective tissue heavily invested with blood vessels.
The superficial surface has structures called:

dermal papillae.

The design of a person's epidermal ridges is determined by the manner in which the papillae
rest upon the dermal ridges to produce the specific pattern known as handprints, footprints, and
fingerprints. Which of the following statements is true regarding these prints or ridges?

They are genetically determined, therefore unique to each person.

30) Which of the following statements indicates the way in which the body's natural defenses
protect the skin from the effects of UV damage?

Prolonged exposure to the sun induces melanin dispersion, which in turn acts as a natural
sunscreen.

Changes in the color of skin are often an indication of a homeostatic imbalance. Which of the
following changes would suggest that a patient is suffering from Addison's disease?

The skin takes on a bronze or metallic appearance

An epidermal dendritic cell is a specialized ________.

phagocytic cell

What are the most important factors influencing hair growth?

nutrition and hormones

Which of the following statements best describes what fingernails actually are?

Fingernails are a modification of the epidermis.

Sudoriferous (sweat) glands are categorized as two distinct types. Which of the following are
the two types of sweat glands?

eccrine and apocrine

The composition of the secretions of the eccrine glands is ________.

99% water, sodium chloride, trace amounts of wastes, and vitamin C

Apocrine glands, which begin to function at puberty under hormonal influence, seem to play
little role in thermoregulation. Where would we find these glands in the human body?

in the axillary and anogenital area

The sebaceous glands are simple alveolar glands that secrete a substance known as sebum.
The secretion of sebum is stimulated ________.

by hormones, especially androgens

In addition to protection (physical and chemical barrier), the skin serves other functions.
Which of the following is another vital function of the skin

It converts modified epidermal cholesterol to a vitamin D precursor important to calcium
metabolism.

Burns are devastating and debilitating because of loss of fluids and electrolytes from the
body. How do physicians estimate the extent of burn damage associated with such dangerous
fluid loss?

by using the "rule of nines

What is the first threat to life from a massive third-degree burn?

catastrophic fluid loss

Male pattern baldness has a genetic switch that turns on in response to ________.

Male Hormones

Eyebrow hairs are always shorter than hairs on your head because ________.

eyebrow follicles are only active for a few months

Cradle cap in infants is called ________.

seborrhea

The white crescent portion of the nail is called the ________.

lunula

The layer of the epidermis immediately under the stratum lucidum in thick skin is the stratum
________.

granulosum

The ________ are the small muscles located in the dermis that cause goose bumps.

arrector pili

The coarse hair of the eyebrows and scalp is called ________ hair

terminal

________ are pigment-producing cells in the epidermis.

Melanocytes

________ burns injure the epidermis and the upper regions of the dermis.

Second-degree

________ are pigment-producing cells in the epidermis.

Melanocytes

The only place you will find stratum ________ is in the skin that covers the palms, fingertips,
and soles of the feet.

lucidum

The dermis is composed of the reticular and ________ layers.

papillary

There are several reasons other than genetics for hair loss. Identify some of these other
factors.

Stressors such as acutely high fever, surgery, severe emotional trauma; drugs such as
antidepressants and chemotherapy drugs; burns and radiation; and a protein-deficient diet can
cause hair loss or thinning.

In addition to the synthesis of vitamin D, keratinocytes are able to carry out some other
biologically important functions. Name at least two of these other functions.

Keratinocyte enzymes can neutralize carcinogens that penetrate the epidermis.
Keratinocytes are also able to convert topical steroid hormones to a powerful anti-inflammatory
drug.

How are burns classified? Give an example

Burns are classified according to their severity or depth. For example, in first-degree
burns, only the epidermis is damaged; in second degree burns, the epidermis and upper dermis
are damaged; in third degree burns, there is widespread damage of epidermis and dermis.

What are vellus hairs?

Answer: pale, fine body hair associated with newborn children, women, and bald men

Balding men have tried all kinds of remedies, including hair transplants, to restore their lost
locks. Explain the cause of male pattern baldness.

It appears to be genetically determined and sex-linked, and is possibly caused by a
delayed-action gene that responds to DHT and alters normal metabolism.

Billions of consumer dollars are spent for deodorants and antiperspirants each year. Explain
the production of body odors frequently associated with axillary skin.

Sweat is mostly an odorless watery secretion produced by eccrine and apocrine glands.
The odor usually arises due to the metabolic activities of bacteria on the surface of the skin.

What complications might be anticipated from the loss of large areas of skin surfaces?

Large losses of skin, as with severe burn injuries, allow excessive fluid loss and
infection. Skin grafting or "synthetic skin" applications are usually necessary.

What are six of the functions of the epidermis?

1. Protection against abrasion.
2. Protection from the sun's radiation.
3. First line of immune system defense.
4. Protection from water loss.
5. Protection from heat loss.
6. Covers the body; interfaces with the outside.
7. Sensory perception

What are the functions of the papillary layer of the skin?

1. Feed and oxygenate the epidermis.
2. Provide touch and pain receptors.
3. Form the underlying foundation for ridges of the hands and toes.

Why are the apocrine sweat glands fairly unimportant in thermal regulation?

They are largely confined to the axillary and anogenital regions rather than distributed
on the body where heat can be more readily dissipated.

Name the four kinds of sudoriferous glands.

1. eccrine
2. apocrine
3. ceruminous
4. mammary

Why is skin not considered a heat barrier for the body?

Answer: The skin proper must retain flexibility to give up excess body heat, so it must not
function as a heat barrier. The hypodermis contains adipose tissue that acts as an insulator. With
this setup, extra blood (and heat) can be shunted above the hypodermis when heat loss is
desirable.

Why is profuse sweating on a hot day good, and yet a potential problem?

Good because the sweat and evaporating of the sweat causes cooling of the body. Bad
because excessive water and salt loss may occur. Fluid and electrolyte imbalances may follow.

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