INTEGUMENTARY SYSTEM

Covering and Lining Membranes

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.

Skin functions

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.

Skin Structure 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.

Appendages of the Skin

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.

Homeostatic Imbalances of the Skin

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.

Developmental Aspects of Skin

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.