Chapter 14 - Skin

Question 1

Intercellular bridges are characteristic of which of the following layers of the epidermis?
(A) Stratum granulosum
(B) Stratum lucidum
(C) Stratum corneum
(D) Stratum spinosum
(E) Stratum basale

Answer 1

D. Observations with an electron microscope show that intercellular bridges are associated with desmosomes (maculae adherentes), linking the processes of adjacent cells in the stratum spinosum. Desmosomes also link cells within the other epidermal layers, but these cells do not form processes characteristic of bridges. The keratinocytes of the stratum basale also contain hemidesmosomes, which attach the cells to the underlying basal lamina (see Chapter 14 II B).

Question 2

Which of the following statements concern­ ing the stratum granulosum is true?
(A) It contains melanosomes.
(B) It lies superficial to the stratum lucidum.
(C) It is the thickest layer of the epidermis in
thick skin.
(D) It contains keratohyalin granules.
(E) It contains large numbers of dividing cells.

Answer 2

D. The stratum granulosum contains a number of dense keratohyalin granules, but not melanosomes. It lies just deep to the stratum lucidum and is a relatively thin layer in the epidermis of thick skin. Only rarely would a cell undergo mitosis in this layer of the skin (see Chapter 14 II B).

Question 3

Which of the following statements about Langerhans cells is true?
(A) They are commonly found in the dermis.
(B) They function as sensory
mechanoreceptors.
(C) They function as receptors for cold.
(D) They play an immunological role in the skin.
(E) They are of epithelial origin.

Answer 3

D. Langerhans cells in the epidermis function as antigen-presenting cells by trapping antigens that penetrate the epidermis and transporting them to regional lymph nodes, where they are presented to T lymphocytes. In this way, these cells assist in the immune defense of the body. They originate in the bone marrow and do not arise from epithelium (see Chapter 14 II C).

Question 4

Meissner corpuscles are present in which of the following regions of the skin?
(A) Dermal reticular layer
(B) Dermal papillary layer
(C) Hypodermis
(D) Stratum basale
(E) Epidermal ridges

Answer 4

B. Meissner corpuscles are encapsulated nerve endings present in dermal papillae, which are part of the papillary layer of the dermis. These corpuscles function as receptors for fine touch (see Chapter 14 III A).

Question 5

Which of the following statements concern­
ing thin skin is true?
(A) It does not contain sweat glands.
(B) It lacks a stratum corneum.
(C) It is less abundant than thick skin.
(D) It contains hair follicles.
(E) Its epidermis does not rest on a basement membrane.

Answer 5

D. In contrast to thick skin, which lacks hair follicles, thin skin contains many of them (see Chapter 14 II D).

Question 6

Which of the following statements about eccrine sweat glands is true?
(A) They are absent in thick skin.
(B) They are holocrine glands.
(C) They have a narrow duct lined by a
stratified cuboidal epithelium.
(D) They secrete an oily material called
sebum.
(E) They empty into hair follicles.

Answer 6

C. Eccrine sweat glands are simple, coiled tubular glands that have a duct lined by a stratified cuboidal epithelium. They are found in both thick and thin skin and are classified as merocrine glands, meaning they release only their secretory product, which does not include cells or portions of cells (see Chapter 14 IV A).

Question 7

Which of the following statements about hair
follicles is true?
(A) They are always associated with an eccrine sweat gland.
(B) They are present in thin skin but not in thick skin.
(C) Their associated arrector pili muscle is composed of striated fibers.
(D) Their hair shaft inserts into the papillary layer of the epidermis.
(E) They do not extend into the dermis.

Answer 7

B. Hair follicles are present only in thin skin. They are associated with sebaceous glands and arrector pili smooth muscle bundles (see Chapter 14 V).

Question 8

Which of the following statements concerning skin melanocytes is true?
(A) They synthesize a pigment that protects against damage caused by UV radiation.
(B) They are located only in the dermis.
(C) They produce keratohyalin granules.
(D) They may give rise to basal cell carcinoma.
(E) They originate from the mesoderm.

Answer 8

A. Melanocytes are present in the stratum basale of the epidermis. They synthesize melanin pigment and transfer it to keratinocytes to protect against damage caused by UV radiation. Melanocytes sometimes give rise to a form of skin cancer called malignant melanoma. They derive from neural crest and migrate into the epidermis early during embryonic development (see Chapter 14 II C).

Question 9

Which of the following statements concerning sebaceous glands is true?
(A) They do not begin to function until puberty.
(B) They employ the mechanism of holocrine secretion.
(C) They are present in thick skin.
(D) They secrete only in response to
hormones.
(E) They produce a watery enzyme-rich secretion.

Answer 9

B. Sebaceous glands produce sebum, an oily material, and release it into the upper shaft of the hair follicle by a mechanism called holocrine secretion (which means the product and cellular debris are both released from the gland) (see Chapter 14 IV C).

Question 10

Which of the following is an appendage of skin?
(A) Meissner corpuscle (B) Langerhans cell
(C) Krause end-bulb
(D) Pacinian corpuscle
(E) Nail

Answer 10

E. The nail is one appendage of the skin. Other skin appendages are hair follicles, sweat glands, and sebaceous glands (see Chapter 14 VI).