THE INTEGUMENTARY SYSTEM
THE INTEGUMENTARY SYSTEM Structure of the Skin 1. The integumentary system consists of the skin, hair, oil and sweat glands, nails, and sensory receptors. 2. The skin is the largest organ of the body in weight. The principal parts of the skin are the epidermis (superficial) and dermis (deep). 3. The subcutaneous layer (hypodermis) is deep to the dermis and not part of the skin. It anchors the dermis to underlying tissues and organs, and it contains lamellated corpuscles. 4. The types of cells in the epidermis are keratinocytes, melanocytes, intraepidermal macrophages, and tactile epithelial cells. 5. The epidermal layers, from deep to superficial, are the stratum basale, stratum spinosum, stratum granulosum, stratum lucidum (in thick skin only), and stratum corneum . Stem cells in the stratum basale undergo continuous cell division, producing keratinocytes for the other layers. 6. The dermis is composed of dense irregular connective tissue containing collagen and elastic fibers.