 composed of epithelium bound to an underlying connective tissue.  Mucous membranes: line body cavities that are open to the outside.  Cutaneous membrane: the skin  Serous membranes: line closed ventral body cavities.  Parietal layer- lines the body cavity  Visceral layer covers the organ  Serous fluid serves as lubricant between the layers.

 protection of deeper tissue from chemicals, bacteria, injury, and drying  regulation of body temperature through radiation and sweating  synthesis of defensive proteins and vitamin D.  The cutaneous sensory receptors are located in the skin.  *Forms a waterproof, stretchy, washable coat that repairs itself when damaged.

 Epidermis  superficial  made of stratified squamous epis (contains keratin and lacks blood vessels.)  Surface cells are dead and continually flake off and are replaced by division of cells in the basal layer.  Melanin, a pigment produced by melanocytes, protects the nuclei of epithelial cells from damaging rays of the sun.  Dermis  composed of dense connective tissue.  site of blood vessels, nerves, and epidermal appendages.  has two regions, the papillary and reticular layers. The papillary layer has ridges, which produce fingerprints.

Formed from the epidermis but reside in the dermis.  Sebaceous glands – oil glands. Produce sebum (keeps skin and hair soft and healthy). Usually connected by a duct into a hair follicle.  Sweat (sudoriferous) glands, under the control of the nervous system, produce sweat, which is connected by ducts to the epithelial surface. Aid in heat-regulation.  Hair -primarily dead keratinized cells produced by the hair bulb.  Nails -hornlike derivatives of the epidermis. Primarily dead keratinized cells.

 Infections and Allergies  The most common skin disorders.  Ex: ringworm is fungal, staph is bacterial, nail fungus, and allergic reactions to poison ivy.

Burns  result in loss of body fluids and invasion of bacteria  represent a major threat to the body.  The severity of the burn depends on the depth of tissue destruction.

Burns, Cont. ◘ first-degree epidermal damage only ◘ second-degree epidermal and some dermal injury ◘ third-degree epidermis and dermis totally destroyed **Third-degree burns require skin grafts.

Skin Cancer ◘ most common cause is exposure to ultraviolet radiation. ◘ Cure of basal cell and squamous cell carcinoma is complete if they are removed before melanoma, a cancer of melanocytes, forms. It is still fairly rare but is fatal in about half the cases.

 The skin is thick, resilient and hydrated in youth, but loses elasticity and thins as aging occurs.  Balding and/or graying occurs with aging. Both have genetic links, but can result from other factors such as drugs, emotional stress, etc.