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

The Skin & Its Tissues

View of Skin & Underlying Tissues

Inhabitants of the Epidermis

Epidermal Layers - Blisters, Calluses &Psoriasis Composed primarily of keratinized stratified squamous epithelial cells -- consisting of 4-5 layers: stratum corneum: outermost layer, keratinized dead epithelium stratum lucidum: layer found in thickest areas of skin stratum granulosum: 3-5 layers of flattened granular cells, developing keratin fibers stratum spinosum: multiple layers of cells stratum basale: deepest layer of single cuboidal or columnar cells, also contains melanocytes - Blisters, Calluses &Psoriasis

Melanocytes 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 Color - Genetics, Environment & Physiology: # of melanocytes - difference in kind, amount & size sunlight, UV light, etc. blood in dermis, blood vessels, freckles & moles other pigments - carotinoids jaundice – liver disorder

Skin Cancer http://www.skincancer.org Squamous cell Basal cell carcinoma Malignant melanoma carcinoma

Dermis: 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

Dermis

Hair & Nails are Derivatives of 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 Follicle

Nails: Protect Ends of Fingers & 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 Glands Sweat glands: Sebaceous glands: - assoc. w/ hair follicles, secrete sebum - oils hair, lubricates skin & prevent water loss - acne vulgaris 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

Eccrine & Apocrine Sweat Glands

Temperature Regulation Homeostatic mechanism - receptor - control center - effectors

Body Temperatures Under Varying Conditions heat exhaustion heat stroke fever hypothermia

Wounds & Healing Inflammation: normal response to injury or stress Laceration: break in the skin 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

Steps of Tissue Repair