Chapter 5

Question 1

Name the tissue types composing the epidermis and dermis

Answer 1

Epidermis: keritinized stratified squamous epithelium
Dermis: connective tissue

Question 2

List the major layers of the epidermis

Answer 2

Stratum basale
Stratum spinosum
Stratum granulosum
Stratum lucidum
Stratum corneum

Question 3

List the major layers of the dermis

Answer 3

Papillary layer

Reticular layer

Question 4

Name the cell types composing the epidermis and dermis

Answer 4

Epidermis: keratinocytes, melanocytes, dendritic cells, tactile cells
Dermis: fibroblasts, macrophages, occasional mast cells and white blood cells

Question 5

Hypodermis

Answer 5

Not part of the skin; consists mostly of adipose tissue; anchors skin to underlying structures, shock absorber, insulator

Question 6

Stratum basale

Answer 6

Deepest epidermal layer; one row of actively mitotic stem cells; some newly formed cells become part of the more superficial layers; occasional melanocytes and dendritic cells

Question 7

Stratum spinosum

Answer 7

Several layers of keratinocytes unified by desmosomes; cells contain thick bundles of intermediate filaments made of pre-keratin

Question 8

Stratum granulosum

Answer 8

Typically 5 layers of flattened cells, organelles deteriorating; cytoplasm full of lamellar granules (release lipids) and keratohyaline granules

Question 9

Stratum lucidum

Answer 9

Visible only in thick skin; two or three rows of clear, flat, dead keratinocytes; tonofilaments

Question 10

Stratum corneum

Answer 10

Most superficial layer; 20-30 layers of dead cells, essentially flat membranous sacs filled with keratin; Glycolipids in extracellular space

Question 11

Papillary layer

Answer 11

Areolar collective tissue in which fine interlacing collagen and elastic fibers form a loosely woven mat with lots of small blood vessels; contains dermal papillae, dermal ridges and epidermal ridges (friction ridges)

Question 12

Reticular layer

Answer 12

Accounts for 80% of the thickness of the dermis; coarse, irregularly arranged, dense fibrous connective tissue; extracellular matrix contains adipose cells and collagen fibers; nourished by the cutaneous plexus; less dense regions form cleavage lines; dermal folds near joints are flexure lines

Question 13

Keratinocytes

Answer 13

Produces keratin; most epidermal cells are keratinocytes

Question 14

Melanocytes

Answer 14

Spider-shaped epithelial cells that synthesize the pigment melanin; found in the deepest layer of the epidermis; protects from UV radiation

Question 15

Dendritic cells

Answer 15

Star-shaped cells that arise from the bone marrow and migrate to the epidermis; ingest foreign substances and key activators of the immune system; Also called Langerhans cells

Question 16

Tactile cells

Answer 16

Occasionally present in the epidermal-dermal junction; intimately associated with a disclike sensory nerve ending which functions as a sensory receptor for touch

Question 17

Describe the factors that contribute to skin color

Answer 17

Melanin, Carotene, Hemoglobin

Question 18

Describe how changes in skin color may be used as clinical signs of certain diseases

Answer 18

Redness (erythema): hypertension, allergy, or inflammation
Pallor (blanching): anemia or low blood pressure
Jaundice: liver disorder
Bronzing: Addison’s disease
Bruises: blood clots beneath the skin
Blue blood and skin: cyanosis

Question 19

List the parts of the hair follicle

Answer 19

Consists of an inner epithelial root sheath and an outer peripheral connective tissue sheath derived from the dermis. The base of the hair follicle is a hair bulb with a matrix that produces hair.

Question 20

What is the functional relationship between the arrector pili muscles and the hair follicles

Answer 20

Attached in such a way that its contraction pulls the hair follicle upright and dimples the skin surface to produce goose bumbs

Question 21

Name the regions of a hair and explain the basis of hair color

Answer 21

Central medulla, cortex, and an outer cuticle and root and shaft portions; Hair color refelects the amount and kind of melanin present

Question 22

Describe the distribution, growth, replacement, and changing nature of hair during the life span

Answer 22

The rate of hair growth varies in different body regions and with sex and age. Differences in life span of hairs account for differences in length on different body regions

Question 23

Describe the structure of nails

Answer 23

Nail bed, nail matrix, root of nail, proximal nail fold, eponychium, body, free edge, hyponychium

Question 24

Compare the structure and locations of sweat and oil glands & the composition and function of their secretions

Answer 24

Sweat: entire skin except nipples and parts of external genitalia; prevent body from overheating; sweat
Sebaceous: simple branched alveolar glands all over the body except palms and soles; sebum; lubricates hair and skin

Question 25

Compare and contrast eccrine and apocrine glands

Answer 25

Eccrine: far more numerous, 99% water with some salts, etc., prevents body from overheating Apocrine: lies deeper in the dermis, similar secretion plus fatty substances and proteins, sometimes milky or yellow, odorless unless bacteria interact

Question 26

Describe how the skin accomplishes 5 functions

Answer 26

Protection: physical, chemical, and biological barriers Body temperature regulation: Dermal blood vessels constrict, causing warm blood to bypass the skin Cutaneous sensation: tactile discs allow us to become aware of when something touches us Blood reservoir: Dermal vascular supply Excretion: Sweating

Question 27

Summarize the characteristics of the 3 major types of skin cancer

Answer 27

Basal cell carcinoma: least malignant Squamous cell carcinoma: Will grow rapidly and metastasize if not removed, but good chance of cure Melanoma: most dangerous; highly metastatic and resistant to chemotherapy

Question 28

Why are serious burns life threatening?

Answer 28

Loss of body fluids containing proteins and electrolytes

Question 29

How can you differentiate first, second, and third degree burns?

Answer 29

First: redness, swelling, pain Second: Like first, but blisters also appear Third: Gray-white, cherry red, or blackened

Question 30

Describe the causes of changes that occur in the skin from birth to old age

Answer 30

In old age, the rate of epidermal cell replacement declines and the skin and hair thin. Skin glands become less active. Loss of collagen and elastic fibers and subcutaneous fat leads to wrinkling; photodamage is a major cause