Chapter 5 Flashcards
Name the tissue types composing the epidermis and dermis
Epidermis: keritinized stratified squamous epithelium
Dermis: connective tissue
List the major layers of the epidermis
Stratum basale Stratum spinosum Stratum granulosum Stratum lucidum Stratum corneum
List the major layers of the dermis
Papillary layer
Reticular layer
Name the cell types composing the epidermis and dermis
Epidermis: keratinocytes, melanocytes, dendritic cells, tactile cells
Dermis: fibroblasts, macrophages, occasional mast cells and white blood cells
Hypodermis
Not part of the skin; consists mostly of adipose tissue; anchors skin to underlying structures, shock absorber, insulator
Stratum basale
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
Stratum spinosum
Several layers of keratinocytes unified by desmosomes; cells contain thick bundles of intermediate filaments made of pre-keratin
Stratum granulosum
Typically 5 layers of flattened cells, organelles deteriorating; cytoplasm full of lamellar granules (release lipids) and keratohyaline granules
Stratum lucidum
Visible only in thick skin; two or three rows of clear, flat, dead keratinocytes; tonofilaments
Stratum corneum
Most superficial layer; 20-30 layers of dead cells, essentially flat membranous sacs filled with keratin; Glycolipids in extracellular space
Papillary layer
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)
Reticular layer
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
Keratinocytes
Produces keratin; most epidermal cells are keratinocytes
Melanocytes
Spider-shaped epithelial cells that synthesize the pigment melanin; found in the deepest layer of the epidermis; protects from UV radiation
Dendritic cells
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
Tactile cells
Occasionally present in the epidermal-dermal junction; intimately associated with a disclike sensory nerve ending which functions as a sensory receptor for touch
Describe the factors that contribute to skin color
Melanin, Carotene, Hemoglobin
Describe how changes in skin color may be used as clinical signs of certain diseases
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
List the parts of the hair follicle
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.
What is the functional relationship between the arrector pili muscles and the hair follicles
Attached in such a way that its contraction pulls the hair follicle upright and dimples the skin surface to produce goose bumbs
Name the regions of a hair and explain the basis of hair color
Central medulla, cortex, and an outer cuticle and root and shaft portions; Hair color refelects the amount and kind of melanin present
Describe the distribution, growth, replacement, and changing nature of hair during the life span
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
Describe the structure of nails
Nail bed, nail matrix, root of nail, proximal nail fold, eponychium, body, free edge, hyponychium
Compare the structure and locations of sweat and oil glands & the composition and function of their secretions
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
Compare and contrast eccrine and apocrine glands
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
Describe how the skin accomplishes 5 functions
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
Summarize the characteristics of the 3 major types of skin cancer
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
Why are serious burns life threatening?
Loss of body fluids containing proteins and electrolytes
How can you differentiate first, second, and third degree burns?
First: redness, swelling, pain
Second: Like first, but blisters also appear
Third: Gray-white, cherry red, or blackened
Describe the causes of changes that occur in the skin from birth to old age
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
