Skin Biology: Wrinkles, Melanin & Tanning

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Which of the following factors contributes to the reduced firmness and recoil ability of the skin after stretching, leading to the formation of wrinkles?

Overproduction of adipose tissue in the epidermis.
Increased production of melanin by melanocytes.
Age-related decrease in collagen fibers and elastic fibers. (correct)
Increased hydration of the stratum corneum.

Why do wrinkles tend to be deeper in areas of repetitive muscle movement, such as the forehead and around the eyes and mouth?

Higher concentration of melanocytes leading to uneven skin tone.
Reduced blood flow and nutrient supply to those regions.
Constant stresses weaken the collagen and elastic fibers. (correct)
Increased deposition of adipose tissue in those areas.

How does Botox minimize the appearance of wrinkles?

By providing additional hydration to the epidermal cells.
By directly stimulating the production of melanin.
By temporarily paralyzing facial muscles. (correct)
By increasing collagen production in the dermis.

What is the primary function of melanin in the skin?

To protect keratinocyte DNA from mutations induced by UV radiation. (A) Signup and view all the answers

In what cellular structure does the production of melanin occur?

Melanosome (C) Signup and view all the answers

How does melanin get transported from the melanocytes to the keratinocytes?

Melanosomes migrate to the ends of melanocyte extensions, are released by exocytosis, and then taken into the cytoplasm of keratinocytes. (D) Signup and view all the answers

Where does melanin accumulate within the keratinocyte to provide protection against UV radiation?

On the superficial side of the nucleus, facing the exterior of the body. (B) Signup and view all the answers

Why is continuous production of melanin necessary for maintaining consistent skin color?

Because melanin degrades after a few days and needs replenishment. (C) Signup and view all the answers

What is the primary mechanism behind the immediate tanning response following exposure to UV radiation?

Oxidation of melanin already present in keratinocytes. (C) Signup and view all the answers

The delayed tanning effect is primarily caused by which of the following mechanisms?

UV light induced DNA damage stimulating melanin production. (B) Signup and view all the answers

Why do individuals in regions with high UV radiation exposure, such as Africa, tend to have darker skin pigmentation?

To prevent excess vitamin D production. (C) Signup and view all the answers

In areas with less UV radiation, like northern Europe, lighter skin pigmentation evolved to facilitate what?

Efficient vitamin D synthesis. (D) Signup and view all the answers

Which statement accurately describes the distribution of melanocytes in the human body?

The number of melanocytes is virtually identical among all individuals, irrespective of skin color. (C) Signup and view all the answers

What primarily determines the spectrum of human skin tones among individuals?

Differences in tyrosinase activity and the type of melanin produced. (B) Signup and view all the answers

An individual with darker skin is exposed to the same amount of UV radiation as an individual with lighter skin. Which of the following is most likely to occur?

The individual with darker skin will have less vitamin D production and slower calcium absorption. (D) Signup and view all the answers

Considering melanin's role in UV radiation absorption, what potential health risk remains for individuals with darker skin pigmentation?

The possibility of developing sunburns and skin cancers despite melanin's protective effects. (C) Signup and view all the answers

What is the primary function of the dermal root sheath?

To support the follicle and keep it separate from the dermis. (D) Signup and view all the answers

The arrector pili muscle is responsible for which of the following?

Causing hair to stand upright and producing goosebumps. (D) Signup and view all the answers

During the growth stage of hair, what process occurs in the matrix?

Mitosis occurs, causing cell division. (D) Signup and view all the answers

What happens to the hair follicle during the resting stage?

The follicle shortens, and the hair is pushed toward the surface. (A) Signup and view all the answers

How does the growth stage affect cells as they are pushed further from the blood supply?

They keratinize and die. (B) Signup and view all the answers

Which of the following is an accurate description of lanugo hair?

Thin, nonpigmented hair covering the fetus' body. (A) Signup and view all the answers

What is the key difference between terminal and vellus hair?

Terminal hair is thick and pigmented, while vellus hair is thinner and nonpigmented. (C) Signup and view all the answers

How does the replacement of vellus hair with terminal hair differ between males and females after puberty?

Males experience more replacement than females. (C) Signup and view all the answers

Pallor, characterized by a loss of the skin's normal pinkish hue, is most visible in pale-skinned individuals due to what underlying factor?

Decreased blood flow in the dermis, causing the epidermis to take on the whitish color of collagen. (C) Signup and view all the answers

Which of the following physiological responses is NOT typically associated with the occurrence of pallor?

Increased blood flow to the dermis. (D) Signup and view all the answers

Cyanosis, indicated by a faint bluish hue in the skin, suggests a critical health issue related to:

Extremely low levels of oxygen bound to hemoglobin in the blood. (C) Signup and view all the answers

Which of the following conditions can lead to cyanosis?

Difficulty breathing. (D) Signup and view all the answers

Hair, nails, and glands are considered accessory structures of the integumentary system because they:

Are derived from epithelium and support the overall function of the system. (B) Signup and view all the answers

Hair is present over the entire surface of the skin EXCEPT:

Regions with thick skin, the lips, and parts of the external genitalia. (C) Signup and view all the answers

What is the primary role of hair in humans?

Detecting changes in the environment and protecting the skin. (D) Signup and view all the answers

How does hair contribute to the sensory perception of the environment?

Through association with small sensory neurons that detect hair movement. (D) Signup and view all the answers

The color of an individual's hair is primarily determined by the:

Type and amount of melanin produced by melanocytes. (B) Signup and view all the answers

Gray or white hair is a result of:

A decrease in melanin production due to the aging. (A) Signup and view all the answers

The nail plate rests on top of the:

Nail bed. (A) Signup and view all the answers

What is the primary function of the hyponychium?

To attach the distal edge of the nail plate to the nail bed. (B) Signup and view all the answers

Nail growth occurs in the nail matrix. As new cells are produced, what happens to the older cells?

They are pushed distally, become keratinized, and eventually die. (B) Signup and view all the answers

The lunula appears whitish due to:

An accumulation of keratin. (B) Signup and view all the answers

Which of the following statements best describes the primary function of nails?

Protection of distal tips of fingers and toes from trauma and enabling precise gripping. (C) Signup and view all the answers

Unlike hair, nails:

Do not contain melanocytes. (B) Signup and view all the answers

Which of the following best describes the primary mechanism by which eccrine sweat glands secrete their products?

Merocrine secretion (exocytosis), releasing products via vesicles. (A) Signup and view all the answers

What is the primary functional difference between eccrine and apocrine sweat glands?

Eccrine glands are primarily involved in thermoregulation, while apocrine glands are associated with scent production. (B) Signup and view all the answers

The activity of apocrine sweat glands is most directly influenced by:

Sex hormones. (D) Signup and view all the answers

Cerumen, produced by ceruminous glands, serves what primary function in the ear?

To trap incoming particles and lubricate the ear canal. (A) Signup and view all the answers

Mammary glands are best classified as:

Highly specialized sweat glands that produce modified sweat (milk). (C) Signup and view all the answers

If a patient reports excessive earwax buildup leading to hearing difficulties, which type of gland is most likely involved?

Ceruminous glands. (B) Signup and view all the answers

What is a key difference in the location of secretion release between apocrine and ceruminous glands?

Apocrine glands secrete into hair follicles, whereas ceruminous glands also secrete into hair follicles. (D) Signup and view all the answers

Why do secretions from Apocrine glands often produce a noticeable odor?

Apocrine secretions are metabolized by skin bacteria, producing odoriferous byproducts. (E) Signup and view all the answers

Melanin

Pigment that increases with UV exposure, leading to tanning.

Immediate tanning response

Quick darkening of melanin already in keratinocytes.