Integumentary Integumentary SystemSystem

Epidermis Skin Color & Cancer Dermis Hair, Nails & Glands Temperature Regulation Wounds & Healing

The Skin & Its TissuesThe Skin & Its Tissues

View of Skin & Underlying TissuesView of Skin & Underlying Tissues

Inhabitants of the EpidermisInhabitants of the Epidermis

Epidermal LayersEpidermal Layers

Composed primarily of keratinized stratified squamous epithelial cells -- consisting of 4-5 layers:

1. stratum corneum: outermost layer, keratinized dead epithelium

2. stratum lucidum: layer found in thickest areas of skin

3. stratum granulosum: 3-5 layers of flattened granular cells, developing keratin fibers

4. stratum spinosum: multiple layers of cells

5. stratum basale: deepest layer of single cuboidal or columnar cells, also contains melanocytes

- Blisters, Calluses &Psoriasis

MelanocytesMelanocytes

Specialized cells in epidermis produce melanin– dark pigment providing skin

color

– cells lie in stratum basale

– cytocrine secretions: cellular extension

– absorbs UV radiation in sunlight

– protects dermis

Skin ColorSkin Color

- Genetics, Environment & Physiology:

1. # of melanocytes - difference in kind, amount & size

2. sunlight, UV light, etc.

3. blood in dermis, blood vessels, freckles & moles

4. other pigments - carotinoids

5. jaundice – liver disorder

Skin CancerSkin Cancerhttp://www.skincancer.orghttp://www.skincancer.org

Squamous cell Basal cell carcinoma Malignant melanomacarcinoma

Dermis: 2 layersDermis: 2 layers Dense CT: composed of collagen, elastin & reticular

fibers:– unevenness b/t layers (dermal papilae) form

fingerprints (epidermal ridges)

– delivers nutrients & O2 to epidermal cells

– binds epidermis to underlying tissue

– contains muscle fibers (facial expressions)

– nerve cells are distributed throughout (e.g., Meissner’s & Pacinian corpuscles)

– hair follicles, sweat & sebaceous glands

DermisDermis

Hair & Nails are Derivatives Hair & Nails are Derivatives of Skinof Skin

Hair: protective function, found on most skin surfaces consisting of epidermal cells & keratin– hair follicle: structure hair develops from

– hair root: portion below skin surface

– hair shaft: extends away from skin surface

– hair color: epidermal melanocytes

– arrector pili muscle: goose bumps

– sebaceous glands: associated w/ hair follicles, lubricate hair & skin

– androgenic alopecia

Hair FollicleHair Follicle

Nails: Protect Ends of Fingers Nails: Protect Ends of Fingers & Toes& Toes

Specialized epithelial cells that keratinize; consist of nail plate & nail bed– Lunula (1/2 moon shape region): active growing area of nail– What can nail appearance indicate?

Skin Skin GlandsGlands

Sweat glands:– Eccrine: deep in dermis or subcutaneous layer, odorless

secretions, function in thermoregulation

– Apocrine: found near hair follicles, in axillary regions, released during pain, fear & stress or sexual arousal

- Ceruminous & mammary glands

Sebaceous glands: - assoc. w/ hair follicles, secrete sebum - oils hair, lubricates skin & prevent water loss

- acne vulgaris

Eccrine & Apocrine Sweat GlandsEccrine & Apocrine Sweat Glands

TemperatuTemperature re RegulationRegulation

Homeostatic mechanism- receptor- control center- effectors

Body Temperatures Under Varying ConditionsBody Temperatures Under Varying Conditions

• heat exhaustion

• heat stroke

• fever

• hypothermia

Wounds & HealingWounds & Healing

– epidermal cut: epithelial cells around injury proliferate & newly formed cells fill in

– dermal cut: clot forms (RBC, platelets, proteins)

– growth factors: induce migration of fibroblast & macrophages

– smooth muscle & fibroblasts stimulate tissue repair

Inflammation: normal response to injury or stress

Laceration: break in the skin

Steps of Steps of Tissue Tissue RepairRepair