CH 5 - THE INTEGUMENTARY SYSTEM

Integumentary System

organ system consisting of skin, hair, nails, and associated glands

Skin (Cutaneous Membrane)

largest organ of the body providing protection and regulation

Functions of Skin

protection thermoregulation sensation vitamin D synthesis and excretion

Epidermis

superficial epithelial layer of the skin

Dermis

connective tissue layer beneath epidermis

Hypodermis

subcutaneous layer composed mainly of adipose and areolar tissue

Epidermis Tissue Type

keratinized stratified squamous epithelium

Avascularity of Epidermis

epidermis lacks blood vessels

Stratum Basale

deepest epidermal layer where active mitosis occurs

Stratum Spinosum

layer containing cells connected by desmosomes

Stratum Granulosum

layer where keratinization begins and cells flatten

Stratum Lucidum

clear layer present only in thick skin

Stratum Corneum

outermost layer of dead keratinized cells

Keratinocyte

most abundant epidermal cell producing keratin

Keratin

tough fibrous protein providing waterproofing and protection

Melanocyte

epidermal cell producing melanin pigment

Melanin

pigment that protects against ultraviolet radiation

Langerhans Cell

immune cell that helps activate immune response

Merkel Cell

sensory cell associated with touch receptors

Dermis Layers

papillary layer and reticular layer

Papillary Layer

superficial dermal layer composed of areolar connective tissue

Dermal Papillae

projections increasing surface area and grip between epidermis and dermis

Reticular Layer

deeper dermal layer composed of dense irregular connective tissue

Dermal Collagen Fibers

provide skin strength and elasticity

Dermal Cleavage Lines (Tension Lines)

lines indicating collagen fiber orientation

Hypodermis Function

insulation energy storage and anchoring skin

Sweat Gland

exocrine gland producing sweat

Eccrine Sweat Gland

produces watery sweat for thermoregulation

Apocrine Sweat Gland

produces viscous secretion active during stress

Sebaceous Gland

produces sebum for lubrication

Sebum

oily substance preventing skin drying

Hair

flexible keratinized filament

Hair Follicle

structure from which hair grows

Hair Matrix

growth zone of hair follicle

Arrector Pili Muscle

smooth muscle that elevates hair

Nail

hard keratinized structure protecting fingertips

Nail Matrix

region where nail growth occurs

Cutaneous Sensory Receptors

receptors detecting touch temperature and pain

Free Nerve Endings

pain and temperature receptors

Meissner's Corpuscle

light touch receptor

Pacinian Corpuscle

deep pressure receptor

Thermoreceptor

receptor detecting heat or cold

Nociceptor

pain receptor

Skin Color Determinants

melanin carotene and hemoglobin

Carotene

yellow-orange pigment accumulating in stratum corneum

Cyanosis

bluish discoloration due to low oxygen

Erythema

redness due to increased blood flow

First-Degree Burn

epidermis only with redness and pain

Second-Degree Burn

epidermis and dermis with blisters

Third-Degree Burn

full thickness skin destruction

Rule of Nines

method of estimating burn surface area

Skin Cancer

abnormal uncontrolled skin cell growth

Basal Cell Carcinoma

least malignant most common skin cancer

Squamous Cell Carcinoma

arises from keratinocytes and may metastasize

Melanoma

cancer of melanocytes most dangerous form

Vitamin D Synthesis

production of vitamin D3 in response to UV light

Aging Effects on Skin

thinning reduced elasticity slower repair