Skin covers body to protect, insulate, an maintain homeostasis. 2 distinct layers bound tightly together. Outer, superficial epidermis. Inner, deep dermis. The tissue beneath the dermis is not part of the skin, loose configuration of fat and areolar tissue that attaches skin to underlying muscles, subcutaneous layer called the hypodermis(superficial fascia). Larger in women
Stratified squamous epithelium keritinized. Consists of 4 types of cells within 4 or 5 layers FYI Keratinocytes- 90% of epidermal cells form keratin Melanocytes: produce the brown pigment melanin. Langerhans cells: phagocytic cells that provide defense from infection. Merkel cells: located deep in the dermis function as touch receptors.
Stratum basale: the Base- single layer of cells columnar or cuboidal **actively mitotic** melanocytes, langerhans, and merkel. Stratum spinosum: “Spines” 8-10 rows of cells mainly keratinocytes. Stratum granulosum: “little grains” 3-5 rows of keratinocytes containing tiny granules. Stratum lucidum: clear(lucid). 3-5 rows of flattened dead keratinocytes. **soles & palms** Stratum corneum: thick outer layer 25 rows or more. Saturated with keratin.
Thick, vascular portion of skin composed of connective tissue. Houses the accessory organs: hair, hair follicles, sebaceous glands and sweat glands. Divided into 2 regions: Papillary Region Reticular Region
Upper 1/5 of the dermal layer. Immediately below the stratum basale. Thin region of areolar tissue arranged in finger- like ridges poking up toward the epidermis the ridges are known as Dermal Papillae. These papillae form the ridges and whorls on the fingers, palms, toes, and soles.
The dominant, deep part of the dermis- composed of dense irregular connective tissue with collagen fibers, elastic fibers, and blood vessels.
AKA- Lamellated Corpuscle One of 2 cutaneous sensory receptors. Found in the Reticular region. Pressure. Large, round swellings with numerous rings of protein fibers. Sliced onion appearance.
Produce sebum an oily substance released through a duct that empties into hair follicles. Found wherever hair follicles are present. Provides an oily lubricant for the surface of hair and skin.
AKA: Sudoriferous gland Located deep in the dermis where they produce watery material deposited into long ducts and empty on the skin’s surface. 2 types: Eccrine widely distributed, produce sweat for temperature regulation. Apocrine Produce a thickened secretion after puberty and found mainly in axillary and inguinal regions.