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Integumentary System

Fall Semester 2004

Learning Objectives, Topics, & Key Terms


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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