Integumentary System
Fall Semester 2004
Learning Objectives, Topics, & Key Terms
Readings: Martini, Chapter 5
Overview/Skin layers
Objectives: 1. Describe the major functions of the integumentary system.
2. Describe the three layers of skin and their significant features and functions.
Overview:
Functions
water proofing, sensation, antimicrobe barrier, mechanical barrier, immunity, thermoregulation (radiate and sweat), vitamin D synthesis, social communication
Structure
three layers: epidermis and epidermal derivatives + dermis + hypodermis
Skin
Epidermis
stratified squamous epithelium
four layers (five in hairless skin) (but just know these two:)
stratum basale (also called stratum germinativum or basal cell layer)
keratinocytes divide here
stratum corneum (cornified layer; keratinocytes are dead here)
keratin (insoluble protein in keratinized layer of stratum corneum)
skin color
melanin (brown-black pigment); (albinos lack enzyme to make it)
made by melanocytes in basal cell layer - protect from UV light
melanin granules are passed to keratinocytes
evolution favors dark skin in sunny climates (and vice versa)
evolutionary tradeoff: vitamin D synthesisvs cancer risk
Skin color is NOT a "racial" characteristic
carotene (yellowish pigment deposited in dermis)
hemoglobin (in red cells in dermal blood vessels, gives pink color to light-skinned persons)
surface patterns follow underlying dermis connective tissue organization
congenital (for example, finger prints)
acquired (for example, stretch marks)
callus forms when pressure or friction stimulates more rapid cell division
more active stratum basale --> thicker epidermis
Dermis
functions: contains the epidermal derivatives and supports the epidermis, blood vessels, nerves
composition: dense irregular connective tissue, collagen, elastic fibers, fibroblasts, sensory nerve endings, mast cells --> histamine, lymphocytes
folded into dermal papillae
Subcutaneous Layer (also called hypodermis or superficial fascia)
a. functions: thermal insulation, cushioning, support blood vessels, nerves
b. composition: loose (areolar) connective tissue (fibroblasts, collagen, adipocytes)
Epidermal Derivatives (Accessory Structures)
Objective: Describe the characteristics and functions of accessory structures.
Understand the biological basis of selected skin diseases
Hair
function (insulation, protection, communication, sensation)
composition (keratin)
regions (bulb, shaft, cortex, medulla; arrector pili)
coloration
Glands
sebaceous glands
secrete sebum (oily, associated with hair follicle, lubricates hair and skin)
sweat glands
eccrine (secretion is watery - for thermoregulation)
apocrine (secretion is proteinaceous - for bad smell??)
ceruminous glands- secrete cerumen (ear wax)
Nails
made of keratin; epidermal derivative
Clinical Significance of Integumentary System
itch and rash (mast cells --> histamine)
wound healing
decubitus ulcers (pressure ulcers, bed sores)
neoplasms (tumors from unregulated cellular growth)
benign tumors(e.g., papilloma (also called, warts)
malignant tumors
basal cell carcinoma
squamous cell carcinoma
malignant melanoma
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Durham Technical Community College
Durham, NC 27703
Last updated 2 September 2003