front 1 Epidermis | back 1 a keratinized stratified squamous epithelium consisting of four distinct cell types and four or five distinct layers. |
front 2 Stratum Basale | back 2 deepest epidermal layer; one row of actively mitotic stem cells; some newly formed cells become part of the more superficial layers. |
front 3 Stratum Spinosum | back 3 several layers of keratinocytes joined by desmosomes. Cells contain thick bundles of intermediate filaments made of pre-keratin. |
front 4 Stratum Granulosum | back 4 one of the five layers of flattened cells, organelles deteriorating; cytoplasm full of lamellar granules (release lipids) and keratohyaline granules. |
front 5 Stratum Lucidum | back 5 present only in thick skin. A very thin transparent band of flattened, dead keratinocytes with indistinct boundaries. |
front 6 Stratum Corneum | back 6 most superficial layer; 20-30 layers of dead cells, essentially flat membranous sacs filled with keratin. Glycolipids in extracellular space. |
front 7 Keratin | back 7 a fibrous protein that gives the epidermis its durability and protective capabilities. |
front 8 Keratinocytes | back 8 (keratin cells) the most abundant epidermal cells, their main function is to produce keratin fibrils. Tightly connected to each other by desmosomes. |
front 9 Melanocytes | back 9 spidery black cells that produce the brown-to-black pigment called melanin. |
front 10 Melanin | back 10 the pigment produced in a specialized group of cells known as melanocytes that gives human skin, hair, and eyes their color. |
front 11 Langerhan's Cells | back 11 aka dendritic cells; play a role in immunity by performing phagocytosis. |
front 12 Merkel Cells | back 12 aka tactile cells; occasional spiky hemispheres that, in combination with sensory nerve endings, form sensitive touch receptors located at the epidermal-dermal junction |
front 13 Dermis | back 13 the dense irregular connective tissue that consists of two principal regions: the papillary and the reticular. |
front 14 Papillary Layer | back 14 the more superficial dermal region composed of areolar connective tissue. It is very uneven and has fingerlike projections from its superior surface, the dermal papillae, which attach it to the epidermis above. |
front 15 Dermal Papillae | back 15 projections that lie on top of the larger dermal ridges. In the palms of the hands and soles of the feet, they produce the fingerprints. |
front 16 Meisner's Corpuscles | back 16 aka tactile corpuscle; are a type of mechanoreceptor. They are a type of nerve ending in the skin that is responsible for sensitivity to light touch. They are most concentrated in thick hairless skin, especially at the finger pads. |
front 17 Capillary Loops | back 17 small blood vessel in the dermal papillae |
front 18 Reticular Layer | back 18 the deepest skin layer. It is composed of dense irregular connective tissue and contains many arteries and veins, sweat and sebaceous glands, and pressure receptors. |
front 19 Pacinian Corpuscles | back 19 aka lamellar corpuscle; are one of the four major types of mechanoreceptor. They are nerve endings in the skin responsible for sensitivity to vibration and pressure. |
front 20 Hypodermis | back 20 aka superficial fascia; is not considered part of the skin. Consists primarily of adipose tissue. |
front 21 Hair Root | back 21 the area beneath the surface of the skin and is embedded within the hair follicle. |
front 22 Hair Shaft | back 22 the region projecting from the surface of the skin. |
front 23 Cuticle | back 23 the keratinized layer of cells that surrounds the cortex and medulla located in the hair shaft and hair root. |
front 24 Cortex | back 24 the keratinized layer of cells surrounding the medulla located in the hair shaft and hair root |
front 25 Medulla | back 25 the center keratinized layer of cells located in the hair shaft and hair root. |
front 26 Hair Bulb | back 26 a collection of well-nourished epithelial cells at the base of the hair follicle |
front 27 Hair Papilla | back 27 a small nipple of dermal tissue that protrudes into the hair bulb from the peripheral connective tissue sheath and provides nutrition to the growing hair. |
front 28 Hair Follicle | back 28 a structure formed from both epidermal and dermal cells. Its inner epithelial root sheath, with two parts (internal and external), is enclosed by a thickened basement membrane, the glassy membrane, and by a peripheral connective tissue (or fibrous) sheath, which is essentially dermal tissue.
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front 29 Arrector Pili Muscle | back 29 small bands of smooth muscle cells that connect each hair follicle to the papillary layer of the dermis. When these muscles contract, the slanted hair follicle is pulled upright, dimpling the skin surface with goose bumps. |
front 30 Sebaceous Glands | back 30 are found nearly all over the skin, expect for the palms of the hands and the soles of the feet. Their ducts usually empty into a hair follicle, but some open directly on the skin surface. |
front 31 Sebum | back 31 the product of sebaceous glands. It is a mixture of oily substances and fragmented cells that acts as a lubricant to keep the skin soft and moist and keeps the hair from becoming brittle. |
front 32 Sudoriferous Glands | back 32 exocrine glands that are widely distributed all over the skin. Outlets for the glands are epithelial openings called pores. |
front 33 Eccrine (Merocrine) Sweat Glands | back 33 produce clear perspiration consisting primarily of water, salts, and urea. Under control of the nervous system, they are an important part of the body's heat-regulating apparatus. |
front 34 Apocrine Glands | back 34 found predominantly in the axillary and genital area. Odor comes from the bacteria living on the skin breaking down the organic components of sweat. |