CH. 6- SKIN & THE INTEGUMENTARY SYSTEM Organ- Two or more kinds of tissues grouped together and performing a specialized function. Membranes- Organs composed of epithelial and connective tissue.

TYPES OF MEMBRANES Serous- line body cavities with NO opening to the outside Mucous- line body cavities WITH opening to the outside Synovial- line inner areas of the joint between the ends of bones Cutaneous- skin, epithelial, outside

SKIN & ITS TISSUES Skin Functions Tissues of the skin Largest organ of the body Helps regulate homeostasis Temp, H2O, sensory receptors Tissues of the skin Epidermis- outside Stratified squamous epithelium Dermis- middle, thicker Fibrous connective, epithelial, muscular, nervous and vascular tissue Subcutaneous layer- inner Loose connective & adipose tissue Binds skin to underlying organs

EPIDERMIS Lacks blood vessels Stratum basale- deepest layer Nourished by dermal blood vessels Cells divide and grow from this layer pushing older ones outward Stratum corneum- outer layer Cells die as they move away from nutrient supply Keratinization- dying cells harden and become waterproof Melanocyte- specialized cells in deep epidermis Melanin- dark pigment that absorbs light Amount of melainin determines skin color

DERMIS & SUBCUTANEOUS Dermis- Subcutaneous Layer (Hypodermis) Mostly fibrous connective tissue that bind epidermis to subcutaneous layer Contains the following: Dermal blood vessels- for nutrients Nerve fibers- motor and sensory Hair follicles Sebaceous glands Sweat glands Subcutaneous Layer (Hypodermis) Continuation of the dermis Provides insulation Contain major vessels for blood supply

Stratum Corneum Stratum basale

ACCESSORY ORGANS OF THE SKIN Hair Follicles- tubelike depression of the epidermis Hair Shaft- made up of keratonized epidermal cells Arrector Pili Muscle- moves follicle Sebaceous Gland- specialized epithelial cells attached to hair follicles Sebum- oily mixture of fatty material and cellular debris Nails- keratonized sratified squamous epithelial cells Sweat glands- exocrine glands Eccrine glands- most common, all over Apocrine glands- armpits & groin