ANP 1106 Lecture Notes - Lecture 2: Stratum Corneum, Stratum Granulosum, Stratum Spinosum
Document Summary
Integumentary system is comprised of the skin and accessory structures (sweat & oil glands, hairs and nails) Structure of the skin 1. 5-4mm thick (varies on region of the body i. e dorsal/frontal); consists of 2 distinct regions: Epidermis epithelial layer; thick, keratinized; simple squamous epithelial (several flat layers of cells) Dermis dense connective tissue; thicker layer. Hypodermis (superficial fascia) not part of the skin, hence subcutaneous (covering) 4 types of epidermal cells (slide 4 and 5 for pictures with labels: keratinocytes - most abundant type of cells. Function: produce keratin, a tough fibrous protein to resist destruction; water control (reduce loss and increase absorption) Produced from dendritic cell; every 20-25 days we get new epidermis; epidermal growth factor stimulates the production of more epidermal cells: melanocytes. Found at the epidermis/dermis boundary; have disc-like sensory nerve ending (touch receptors) *stratum basale deepest layer: actively dividing stem cells (b/c they are close to food source connective tissue)