Protection- mechanical, chemical, bacterial Body temperature regulation Prevent water loss Metabolic- synthesize vitamin D Cutaneous Sensation Blood reservoir Excretion Prevent UV damage

An organ, cells constantly dying and being replaced Facts: Weighs 9-11 lbs s.a. = 1.5-2m 2 1 cm 2 has 70 cm blood vessels, 55 cm nerves, 100 sweat glands, 15 oil glands, 230 sensory receptors New skin produced in days

Keratinocytes (90%)- waterproofs & protects skin, nails, hair, stratum corneum Melanocytes (8%)- produce melanin Merkel Cells- slow mechanoreceptors Langerhans’ Cells- immunological defense

Stratum Corneum Stratum Lucidum Stratum Granulosum Stratum Spinosum Stratum Basale- (Germinativum)

Dermis

papillary dermis reticular dermis

a. Cellular Fibroblasts (synthesize collagen, elastin, and reticulin), histiocytes, endothelial cells, perivascular macrophages and dendritic cells, mast cells, smooth muscle, and cells of peripheral nerves and their end-organ receptors. b. Fibrous Collagen & reticulin - provide tensile strength Elastic fibers- provide for restoration of shape after a deformation c. Ground substance glycosaminoglycans: hyaluronic acid, chondroitin sulfate, and dermatan sulfate.

This layer contains adipose tissue and serves to attach the dermis to its underlying tissues. Hypodermis

Some variations in human skin color (Sub-Saharan African, Indian, Southern European, and Northwest European) Melanin Pigments: Eumelanin: Phaeomelanin > Eumelanin:Phaeomalanin- darker skin and hair color; < Eumelanin:Phaeomalanin- lighter skin and hair color Skin color due to: Melanin, Carotene & Hemoglobin

I -light skinned, burns easily, never tans II - light skinned, burns easily, tans some III - light skinned, burns occasionally, tans well IV - light skinned, tans well, rarely burns V - brown skinned (Asian, Indo-Asian, Chinese, Japanese), tans well, burns rarely, can sunburn after prolonged exposure to UVR VI - black skinned (Afro-Caribbean), deeply pigmented, can burn after prolonged exposure to UVR 25% US pop Human complexions are generally classified into six skin types:

Cyanotic Jaundice Erythema Pallor

Pigmentation levels usually increase with age. - exception: premature graying Normal pigmentation may be altered by genetic defects or by acquired diseases. -Hyperpigmentation- age spots -Hypopigmentation- vitiligo, albinism

External agents can also alter skin color. lightening agents carotene dyes Some internal compounds--such as the byproducts of hemoglobin metabolism--may color the skin. Sunless tanning

Malignant melanoma 2% of all cancers Risks: 1.Skin type 2.Sun exposure 3.Family history 4.Age 5.Immunological status A= asymmetry B= border C= color D= diameter Normal mole Melanoma

Sweat Glands Eccrine (merocrine) glands- sweat Apocrine glands- axillary & anogenital areas Ceruminous glands- ears canal Mammary glands- female reproductive glands Ceruminous glands Sweat glands

Sebaceous

Hair Sebaceous gland Hair shaft Hair root Hair bulb in follicle

Nail

1 st Degree: epidermal damage Ex. sunburn 2 nd Degree: epidermis & upper dermis Ex. blisters 3 rd Degree: entire thickness of skin

Blood vessels dilate WBC & clotting agents released Scab forms

Granulation tissue forms Capillary beds invade clot Clean up begins

Scar area has contracted Epithelium regeneration begins

1.In which lay of skin are blood vessels located? 2.Where does epithelium regeneration begin? 3.What color is a persons skin if they are cyanotic? 4.List the layer of the epidermis in order from top to bottom. 5.What is the primary tissue of the hypodermis? 30