Chapter 5

Question 1

Skin layers and component

Answer 1

Consists of two distinct regions
–Epidermis—superficial region
•Epithelial tissue
–Dermis
—underlies epidermis
•Mostly fibrous connective tissue
Hypodermis (superficial fascia)
–Subcutaneous layer deep to skin
–Not part of skin but shares some functions
–Mostly adipose tissue that absorbs shock & insulates
–Anchors skin to underlying structures – mostly
muscles

Question 2

Layers and cells of epidermis

Answer 2

Keratinized stratified squamous epithelium
•Four or five distinct layers
–Stratum basale
–Stratum spinosum
–Stratum granulosum
–Stratum lucidum
(only in thick skin)
–Stratum corneum

•Four cell types
–Keratinocytes
–Melanocytes
–Dendritic (Langerhans) cells
–Tactile (Merkel) cells

Question 3

Skin markings

Answer 3

-cleavage lines (langer's lines) 
because most
collagen fibers parallel to skin surface
•Externally invisible
•Important to surgeons
•Incisions parallel to cleavage lines gap less and heal
more readily

-Flexure lines
–Dermal folds at or near joints
–Dermis tightly secured to deeper structures
–Skin cannot slide easily for joint movement
causing deep creases
–Visible on hands, wrists, fingers, soles, toes

Question 4

Skin color

Answer 4

-Melanin: Two forms
–Reddish-yellow to brownish-black
•Color differences due to amount and form
•Produced in melanocytes
–Same relative number in all people
•Migrates to keratinocytes to form “pigment
shields” for nuclei
•Freckles and pigmented moles
–Local accumulations of melanin
•Sun exposure stimulates melanin production
•Sunspots (tinea versicolor) are fungal infection;
not related to melanin

• Carotene: yellow to orange pigment, palms and soles, accumulates in stratum corneum and hypodermis.
• Hemoglobin: pinkish on fair skin

Question 5

Skin color in diagnosis

Answer 5

Cyanosis (blue skin due to low oxygen of hemoglobin)
Erythema (redness due to hypertension, fever, allergy)
Pallor (blanching due to anger, low bp, anemia)
Jaundice (yellow due to liver disorder)
Bronzing (due to steroid hormones)
Bruising (clotted blood under skin)

Question 6

Hair is made up of?? Pigments

Answer 6

•Dead keratinized cells of hard keratin
–More durable than soft keratin of skin
•Not in palms, soles, lips, nipples, portions of external genitalia
•Functions include
–Warn of insects on skin
–Physical trauma
–Heat loss
–Sunlight
•Hair pigments
–Melanins (yellow, rust, brown, black); trichosiderin in red hair
–Gray/white hair: decreased melanin production, increased air
bubbles in shaft

Question 7

Alopecia

Answer 7

Hair Thinning and Baldness
•Alopecia
–Hair thinning in both sexes after age 40
•True (frank)
baldness
–Genetically determined and sex-influenced
condition
–Male pattern baldness caused by follicular
response to DHT (dihydrotestosterone)
–Treatments
•Minoxidil (rogaine) and finasteride (propecia)

Question 8

Nails

Answer 8

•Scalelike modifications of epidermis
•Protective cover for distal, dorsal surface
of fingers and toes
•Contain hard keratin
•Nail matrix
–Hair growth

Question 9

Types of sweat glands

Answer 9

•Also called sudoriferous glands
•All skin surfaces except nipples and parts of external genitalia
•~3 million per person
•Two main types
–Eccrine (merocrine)
sweat glands
–Apocrine sweat glands
•Contain myoepithelial cells
–Contract upon nervous system stimulation to force
sweat into ducts

Question 10

Eccrine

Answer 10

•Most numerous
•Abundant on palms, soles, and forehead
•Ducts connect to pores
•Function in thermoregulation
–Regulated by sympathetic nervous system
•Their secretion is sweat
–99% water, salts, vitamin c, antibodies,
dermcidin (microbe-killing peptide), metabolic wastes

Question 11

Sebaceous gland (from the slides)

Answer 11

•Confined to axillary and anogenital areas
•Sweat + fatty substances + proteins
–Viscous; milky or yellowish
–Odorless until bacterial interaction
body odor
•Larger than eccrine sweat glands
•Ducts empty into hair follicles
•Begin functioning at puberty
–Function unknown but may act as sexual scent gland
•Modified apocrine glands
–Ceruminous glands —lining of external ear canal;
secrete cerumen (earwax)
–Mammary glands– secrete milk

Question 12

Skin cancers and burns from the slides

Answer 12

•Most skin tumors are benign (not cancerous)and do not metastasize
(spread)
•Risk factors
–Overexposure to UV radiation
–Frequent irritation of skin
•Some skin lotions contain enzymes that can
repair damaged DNA
•Three major types of skin cancer
–Basal cell carcinoma
–Squamous cell carcinoma
–Melanoma