Integumentary System Cover & Protect

Functions of the Skin PROTECTS - from injury, chemicals, temperature, & bacteria PREVENTS water loss by producing keratin – a water proofing protein REGULATES body temperature EXCRETES excess wastes PRODUCES Vitamin D PROVIDE information about our environment

Epidermis - the outer layers of the skin made up of stratified squamous epithelium that is capable of keratinizing Dermis - deep layer of the skin; composed of dense, irregular connective tissue. subcutaneous tissue, or hypodermis - adipose tissue anchor the skin to underlying organs

Structures of the Epidermis STRATUM BASALE - deepest cell layer of the epidermis - connected to dermis along a wavy borderline that resembles corrugated cardboard - contains epidermal cells that receive the most adequate nourishment - millions of new cells are produced daily

Structures of the Epidermis STRATUM SPINOSUM & STRATUM GRANULOSUM - Cells become increasingly flat and full of keratin – water-proofing protein STRATUM LUCIDUM Layer in which cells die- only found where skin is hairless and extra thick - the palms of the hands and soles of the feet

Structures of the Epidermis STRATUM CORNEUM (outermost layer) 20 to 30 cell layers thick Cells are completely filled with keratin Creates hard layer that protects cells underneath Average person loses 18 kg (40 lb) of this layer in their lifetime Replaced by cells of stratum basale every 25 to 45 days

MELANOCYTES a cell that produces melanin Melanin - dark pigment responsible for skin color

Structures of the Dermis PAPILLARY LAYER Upper dermal region that is uneven Has projections called dermal papillae which indent the epidermis above Papillae of hands and feet are arranged in definite patterns – these form looped and whorled ridges Layer that houses touch (Meissner’s corpuscles) and pain receptors (free nerve endings)

Structures of the Dermis RETICULAR LAYER Deepest skin layer Contains blood vessels, sweat and oil glands Has deep pressure receptors called Pacinian corpuscles Contains collagen fibers which gives the skin its strength Contains elastic fibers which give skin elasticity when we are young

SKIN PIGMENTS Amount and kind of melanin – ranges from yellow to brown to black Amount of carotene – a yellow-orange pigment found in foods like carrots – the body deposits it in stratum corneum and subcutaneous layer Amount of oxygen-rich hemoglobin – blood pigment that shows through from the dermal capillaries

SKIN APPENDAGES SEBACEOUS GLANDS Produces oils (sebum) that keep skin moist and soft Prevents hair from becoming brittle Sebum contains chemicals that kill bacteria

SKIN APPENDAGES SWEAT (SUDORIFEROUS) GLANDS ECCRINE - numerous and are found all over the body; produce sweat; important and highly efficient part of the body’s heat-regulating equipment APOCRINE - confined to the axillary and genital areas of the body; usually larger; ducts empty into hair follicles

SKIN APPENDAGES HAIR Produced by an epithelial structure called the hair follicle Composed of three layers: medulla (inner layer), cortex (middle layer) & cuticle (outer layer) The cuticle is formed by highly keratinized, dead epithelial cells The arrector pili muscle attached to the hair follicle are the cause of “goose bumps”

SKIN APPENDAGES NAILS Modifications in the epidermis having free edge, nody (visible attached portion) and root (embedded in skin) Heavily keratinized and colorless – appear pink because of blood supply below Grows from the nail bed or matrix

BURNS BURN – damage or cell death caused by intense heat 1st Degree - only the epidermis is damaged; area is red and swollen; generally heal in two to three days; Sunburn 2nd Degree - injury to the epidermis and the upper region of the dermis; skin is red and painful, and blisters appear 3rd Degree - destroy the entire thickness of the skin; blanched (gray-white) or blackened

SKIN DISORDERS ATHLETE’S FOOT – itchy, red, peeling condition between toes – caused by a fungus COLD SORES – fluid filled blisters that itch & sting – caused by herpes simplex infection- activated by upset, fever or UV light PSORIASIS – chronic condition producing too many skin cells – believed to be an autoimmune disorder in which the immune system attacks a person’s own tissues

SKIN DISORDERS ACNE – condition caused by the overproduction in the hair follicles – prevalent in teens because of hormonal changes Basal Cell Carcinoma – most common skin cancer – appear as lesions in areas that have been exposed to a lot of sun – relatively slow growing

SKIN DISORDERS Squamous Cell Carcinoma – appears as a red, scaley lesion – eventually forms an ulcer on the surface of the skin – appear most often on scalp, ears, dorsum of the hands, and lower lip- also believed to be sun-induced Malignant Melanoma – begins wherever there is pigment – appears spontaneously or where there is existing pigment

DIAGNOSIS - ABCs A) Asymmetry- sides of the pigmented spot or mole do not match B) Border irregularity - borders of the lesion are not smooth but exhibit indentations. C) Color - pigmented spot contains areas of different colors (blacks, browns, tans, and sometimes blues and reds). D) Diameter - spot is larger than 6 millimeters (mm) in diameter (the size of a pencil eraser). E)Elevation – above skin surface