AP 1 : Chapter 5-Skin

Vitamin D, following activation in the skin, is converted to the hormone calcitriol by enzymes in the liver and kidneys. People in northern climates who may not get adequate sun exposure can become deficient in vitamin D. What mineral would be especially affected by this?

calcium

"Goose bumps" are caused by

contraction of arrector pili muscles.

Which might be due to a decrease in the amount of oxygen in the blood?

cyanosis

Differences in skin pigmentation are due to the number of melanocytes in the basal layer of the skin. People with darker skin have many more melanocytes than people with paler skin.

false

tructure composed of epithelium and surrounding the root of a hair from which hair develops.

hair follicle

Which feature(s) of the skin protect(s) us against microbes such as bacteria?

(a)The many layers of keratinized cells form a barrier against microbes (b)Sebum contains compounds which kill bacteria (c)Sweat has an acidic pH which suppresses microbial growth (d)Langerhans cells can alert the immune system should microbes invade ---All of these are correct

Which pigment secreted by specialized cells in the skin is capable of absorbing ultraviolet light?

Melanin

Which of the following statements is correct?

Melanin, carotene and hemoglobin impart color to the skin. The amount of melanin causes skin's color to vary from pale yellow to black. The differences in skin color are due to the amount of melanin produced and moved to the keratinocytes. (All of these statements are correct.)

Tactile epithelial cells are located in the

Stratum Basale

Which layer has stem cells that undergo cell division to continually produce new keratinocytes?

Stratum Basale

This skin layer is only present in places subjected to high levels of mechanical wear-and-tear, and provide an additional protective layer where it occurs, such as in the soles of the feet, palms, and fingertips.

Stratum Lucidum

Langerhans cells are part of the skin's immune defenses and activate other immune cells when the skin is invaded by microbes. Which layer of the epidermis contains Langerhans cells?

Stratum Spinosum

Epidermal ridges are formed by downward projection of the epidermis into the dermis between the dermal papillae of the papillary region.

true

Examination of the nail beds and gums of the mouth are diagnostic tools for anemia in dark skinned individuals.

true

In addition to a thicker stratum corneum and the presence of a stratum lucidum, the thick skin of the palms and fingertips of the hands and of the soles of the feet have a denser array of sense receptors than thinner skin found elsewhere on the body, and also is hairless.

true

It takes 4-6 weeks for a keratinocyte to form in the stratum basale, become keratinized in its journey through the upper layers of the epidermis, and to finally be sloughed off as a dead skin cell.

true

Stimulation of neurons in the skin gives rise to tactile sensations, thermal sensations, and pain.

true

The accumulation of melanin into freckles is a genetic trait. These patches of pigmentation tend to darken with sun exposure and fade during the winter when there is less exposure to the sun.

true

The cells of the stratum basale become more metabolically active and increase their rate of cell division when upper layers of the epidermis are stripped away due to abrasions or burns.

true

The integumentary system is composed of skin, hair, oil and sweat glands, nails and sensory receptors.

true

The skin helps to regulate body temperature by producing perspiration and adjusting blood flow to the dermis.

true

Which statements are true? 1. The majority of the skin does not contain stratum lucidum; 2. Stratum lucidum is found in areas of high friction, such as the palms and soles; 3. Live keratinocytes are located in the stratum lucidum; 4. Friction will cause the stratum lucidum to form calluses.

1 and 2

Which statements describe the function and structure of the skin? 1. Collagen is the strongest fiber in the skin; 2. Blood vessels in the dermis supply the epidermis with nutrients; 3. The arrangement of epidermal ridges, mixed with sweat create fingerprints; 4. The papillary layer is the strongest portion of the dermis; 5. The reticular layer promotes stretching of the skin.

1, 2, 4, 5

Smooth muscles attached to hairs; contraction pulls the hairs into a vertical position, resulting in "goose bumps."

Arrector pili

In a skin infection, which cell will take up and process microbial antigens?

Intraepidermal macrophages (Langerhans cells)

About 90% of the cells of the epidermis are of which type?

Keratinocytes

n exocrine gland in the dermis of the skin, almost always associated with a hair follicle, that secretes sebum.

Sebaceous glands

A layer of dense irregular connective tissue lying deep to the epidermis

dermis

Which type of epithelium makes up the epidermis?

keratinized stratified squamous

The moon-shaped white area at the base of a nail.

lunula

Albinism is the inherited inability to produce

melanin

The pigment-producing cells of the epidermis are located in which layer?

stratum basale

You stepped on a nail. List the sequential strata of the epidermis that the nail penetrated through to reach the dermis.

corneum, lucidum, granulosum, spinosum, basale

The portion of the epithelium proximal to the nail root.

nail matrix

The external covering of the body that consists of a superficial, thinner epidermis (epithelial tissue) and a deep, thicker dermis (connective tissue) that is anchored to the subcutaneous layer. Also called the cutaneous membrane.

skin

Which layer consists on average of 25 to 30 layers of flattened dead keratinocytes.

stratum corneum

Which structure found in the skin plays an important role in thermoregulation?

sweat glands

Homeostatic regulation of body temperature through sweating and adjustment of blood flow in the dermis.

thermoregulation

Which of the following is not a correct statement about melanin?

(a)granules of melanin are produced and exported by melanocytes (b)melanin granules are the source of skin pigmentation (c)melanin is necessary for the production of vitamin D by the skin (d)melanin pigment protects DNA from damaging UV light (e)melanin granules are taken up by keratinocytes (c)-incorrect

Which statement is not correct about the dermis?

(a)it is made up of dense, irregular connective tissue (b)it is thinner in men than in women (c)it contains collagen and elastin fibers (d)it provides the blood supply and many sensory receptors for the epidermis (e)it has a smaller papillary layer, and a thicker reticular layer (b)-incorrect

A tactile receptor within the dermis that is sensitive to touch.

Corpuscles of touch

The skin is also known as a (the) _________.

Cutaneous membrane

What criteria are used to distinguish thick and thin skin?

Distribution on body Thickness and number of layers of epidermis Number and types of glands present. Presence of epidermal ridges (All of these are criteria used.)

Narrow band of stratum corneum at the proximal border of a nail that extends from the margin of the nail wall. Also called the cuticle.

Eponychium

Which of the following are characteristics of thick skin?

Found in the palms, soles of the feet and fingertips. Does not contain hair follicles. Contains more sweat glands than thin skin. Contain epidermal ridges.

The epidermis and dermis differ in

Vascularization Viability of cells Presence of sensory receptors Types of cells present (All of these)

The superficial, thinner layer of skin, composed of keratinized stratified squamous epithelium.

epidermis

A threadlike structure produced by hair follicles that develops in the dermis. Also called a pilus (Pī-lus); plural is pili (Pī -lī)

hairs