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79 Cards in this Set
- Front
- Back
Protection
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Skin acts as a physical, chemical and biological barrier, to offer protection against damage & infection. Also a barrier to water, inhibiting the loss or absorption of water
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Thermoregulation
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Maintains body temperature through sweating or by increasing blood flow to skin, or increase temperature through decreasing blood flow & sweating.
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Cutaneous Sensations
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Sensations of heat, cold, itch, touch, pain etc via large amount of nerve endings & receptors in the skin
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Excretion and absorption
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Absorption of some lipid soluble materials, & excretion of waste materials from the skin’s glands.
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Vitamin D production
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Contains a vitamin d precursor molecule that changes when exposed to light to vitamin d. Vit D is necessary to absorb calcium from the digestive system. Vit D is activated by the kidneys and liver to become a form the body can use.
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Reservoir for blood
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8-10% of blood volume is found in the blood vessels of the dermis
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cutaneous membrane
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aka skin, 2 layers. Superficial, thinner portion composed of pithelial tissue=epidermis. Deeper thicker connective tissue part=dermis
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subcutaneous layer
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aka hypodermis, deep to the dermis not part of skin composed of areolar and adipose tissues. storage for fat and large blood vessels that supply the skin.
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Keratin
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tough, fibrous protein that helps protect the skin and underlying tissues from heat, microbes, and chemicals.
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Keratinocytes
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90% of epidermal cells, form the protective layer. produce the protein keratin and lamellar granules which release a water-repellent sealant.
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Melanocytes
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8% of epidermal cells, deep in epidermis. produce the pigment melanin which provides protection from ultraviolet light
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Langerhans cells
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arise from red bone marrow and migrate to the epidermis, special type of white blood cell, release hystamines. participate in immune responses against microbes
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Merkel cells
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least numerous epidermal cells, located in the deepest layer where they contact the flattened process of a sensory neuron called a tactile (merkel) disc.
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Layering of the epidermis-superficial to deep
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1)Stratum corneum 2)Stratum lucidum -thick skin only 3)Stratum granulosum 4)Stratum spinosum 5)Stratum basale
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Thick skin is found
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Palms, fingers, soles of feet. thick stratum spinosum and corneum, stratum lucidum is present, more dermal papillae (palm, finger,foot prints)
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Dermis
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2nd deeper part of the skin composed mainly of connective tissue, blood vessels, nerves, glands, and hair follicles.
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Papillary layer
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1/5 of total dermal layer. areolar connective tissue.
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Dermal Papillae
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fingerlike projection of the papillary region of the dermis that may contain capillary loops (blood capillaries) some contain touch receptors called corpuscles of touch and free nerve endings. blood vessels in the dp reduce the distance to each cell...nutrients can reach the cells and waste doesn't accumulate
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Reticular layer
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deep layer of the dermis that is attached to the subcutaneous layer. dense irregular connective tissue, a few adipose cells, hair follicles, nerves, sebaceous glands and sudoriferous (sweat)glands.
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Capillary loops
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smooth muscle sphincters regulate blood flow. Normal conserve heat, blushing lose heat.
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Color of skin
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Melanin, hemoglobin, and carotene 3 pigments that create wide variety of skin colors.
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Hair
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aka pili, offers some protectin from injury and sun (head) decreases heat loss, protects eyes, ears, nose from foreign particles, sensing light touch
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hair shaft
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superficial portion of the hair which projects above the surface of skin
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hair root
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portion of hair deep to the shaft that penetrates into the dermis and sometimes into the subcutaneous layer.
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3 concentric layers of hair
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shaft and root have inner medulla layer, middle cortex, and the cuticle.
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hair follicle
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surrounds the root of the hair made up of an external root sheath and and internal root sheath together reffered to as an epithelial root sheath.
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bulb
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base of each hair follicle. houss the papilla of the hair (contains areolar tissue and blood vessels that nourish the growing hair. also contains a germinal layer of cells called the matrix.
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hair growth
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eash follicle goes through a growth stage and a resting stage. during growth cells of the matrix differentiate, keratinize and die as new cells are added at the base of the hair root it grows longer. after resting hair falls out and new hair begins to grow in its place.
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Sebaceous glands
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usually connected to hair follicles, secrete oil onto cuticle of hair. strengthen hair
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eccrine sweat glands
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sweat on to surface of skin, more common. located in the deep dermis sometimes the upper subcutaneous layer
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apocrine sweat glands
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sweat onto hair, armpits and groin, begin to function at puberty.
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Nails
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plates of tightly packed, hard, dead, keratinized epidermal cells.
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nail matrix
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deep to the nail root were cells divide by mitosis to produce growth
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nail root
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portion that is buried in a fold of skin
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epinychium
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aka cuticle a narrow band of epidermis that extends from and adheres to the margin of the nail wall
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hyponychium
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secures nail to fingertip
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nail growth
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cells divide by mitosis in the matrix, specialize into nail cells.
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superficial wounds
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only damage to the epidermis, doesn't bleed. cells in the stratum basale divide and migrate to cover the wound and the other layers are replaced from the stratum basale, a little pain b/c nerve projections in epidermis.
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deep wound healing
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when a wound extends to the dermis and subcutantious layer. 4 stages.
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Inflammatory phase
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blood clot forms, inflammation helps eliminate microbes, foreign material and dead cells. WBC, phagocytes migrate into area, blood vessels open up to get more blood flow to area.
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Migratory phase
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scab forms, migration of stratum basale, fibroblasts migrate, blood vessels grow. begins process of healing.
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Proliferative phase
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epithelial growth, random collagen, blood vessels grow.
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Maturation phase
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scab sloughs off. organized collagen, normal circulation.
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neutrophils
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phagocytic white blood cells. come during inflammatory phase
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monocyte
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develop into macrophages that phagocytize microbes. come during inflammatory phase
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first degree burn
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damage to epidermis
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second degree burn
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damage to dermis
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third degree burn
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damage to hypodermis and deeper tissues
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accessory structures of the integumentary system
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hair nails and glands
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Two layers of the skin
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Epidermis and dermis
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Hypodermis
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Is associated but not part of the skin. It is composed largely of adipose and areolar tissue and it anchors the skin to its underlying structures, such as muscle.
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Stratum Basale
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The deepest layer of the skin. These cells rest on the basement membrane and are stem cells capable of dividing and replace lost skin cells. A scattering of cells in this area include keratinocytes, melanocytes, Langerhans and merkel cells. One row of cuboidal or columnar keratinocytes.
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Stratum Spinosum
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This layer is several cell layers (fitted closely together)thick and the cells are connected with desmosomes. Cells contain keratin protein fibers and lamellar bodies. Langerhan’s and melanocyte cells are found most often in this layer in small numbers. The thickest layer of the epidermis.
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Stratum Granulosum
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Found in the middle of the epidermal layer, it has up to five layers of flattened, dead keratinocytes . Cells become squamous, fill with keratin, produce lipids for waterproofing (lamellar granules)
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Stratum Lucidum:
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This layer is only found in only in thick skin and is lacking entirely in the thinner skin that covers most of your body. Areas of thick skin would be the palm of your hands & the soles of your feet(High friction areas).Three to five layers of dead, flattened keratinocytes, clear in appearance.
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Stratum Corneum:
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This is the most superficial layer of skin. Cells in this layer are cornified to protect against abrasion and penetration and are waterproofed by deeper lamellar granules present between the cells. Cells are constantly being sloughed off from this layer and replaced by cells produced in a deeper layer. Up to 30 layers of dead, flat keratinocytes.
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Dermis has two layers
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1) Papillary2) Reticular
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Papillary Layer
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This is the most superficial layer of the dermis. It is composed of loose areolar connective tissue and is highly vascularized with cutaneous receptors present. The dermal papillae of this region project into the epidermis to form a wavy border. Meissner’s Corpuscles which are light touch sensory receptors are found within this region.
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Reticular Layer
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This region accounts for the majority of the dermal area. It is composed of dense irregular connective tissue and is highly vascularized. Pacinian receptors that detect deep pressure are found within this layer along with sensory nerve endings. Hair follicles, arrector pili, and glands are also present within this layer.
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Skin color is determined by the presence of which three pigments
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Melanin,Carotene,Hemoglobin
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Melanin-description
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Only pigment found in the skin, comes from melanocytes. Its production depends on amino acid tyrosine in the presence of the enzyme tyrosinase. It is taken up by keratinocytes which make them shed their nuclei.Present in larger amounts in the tip of the penis, nipples, face and limbs. Freckles are an accumulation of melanin.
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Melanin-function
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Protects the skin from UV light, increase light-increased melanin-tan produced. Person’s skin colour is determined by how much melanin is produced, not by the amount of melanocytes which remains the same.
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Melanocytes
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Found in the stratum basale produce melanosomes full of melanin which are phagocytized by the keratinocytes in the upper layers of the epidermis. Melanocytes are activated to increase their production of melanin when they are exposed to ultraviolet radiation. This is why you tan. This increased melanin protects the DNA from damage.
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Carotene
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Yellow/orange to reddish pigments obtained from dietry fruits and vegetables. Some are precursors of Vit A, used to synthesis a pigment needed for vision.Found stored in the stratum corneum, fatty areas of the dermis, & subcutaneous area, excess intake will show up as a discolouration in the soles and palms.
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Hemoglobin
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Is the pigment found in red blood cells. This pigment is responsible for the red color of oxygenated blood(when deoxygenated it’s purple/blue). This pigment contributes to the 'rosiness' of skin. The lighter the color of melanin present, the greater influence hemoglobin has on overall coloration. Additionally, the closer blood vessels are to the skin, the more apparent this pigment is.
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Albinism
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An inherited condition of an inability to produce melanin, melanocytes are unable to synthesis tyrosinase. Melanin is missing from their eyes, skin and hair.
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Vitiligo
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Irregular white spots, from a partial or complete loss of melanocytes. Possibly due to immune system malfunction, where antibodies attack melanocytes.
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Two main types of glands
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Sweat and oil
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Sudoriferous (sweat) glands
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Sweat glands are extremely numerous, covering almost the entire body (except nipples and parts of the external genitalia). Sweat glands may be classified as either eccrine or apocrine, depending upon the substance they secrete.
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Eccrine sweat glands
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These are found over most of the body and are the most numerous type of sweat glands. They secrete a type of sweat which is largely composed of water (approximatley 99%) which is filtrated from the blood. In addition to water, minute amounts of salts, metabolic wastes, antibodies, lactic acid and vitamin C make up the other approximately 1% of sweat's composition. Heat activated or emotionally induced. Maintainance of body temperature.
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Apocrine sweat glands
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These sweat glands are found only in armpit & groin areas of the body. They secrete sweat into hair follicles & their sweat is similar in composition to that of the eccrine sweat glands except for added fatty substances and proteins. This makes this sweat more viscous with a slightly whitish tinge to it.
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Sebaceous (oil) glands
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These glands secrete sebum or oil either into a hair follicle or to the surface of the skin. Sebum helps maintain skin and hair textures by slowing water loss, and making it softer. Additionally, sebum is bactericidal.
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How is hair color determined?
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by the amount and kind of melanin pigment produced within the hair cortex by melanocytes and may change over time. White/gray hair has drastically decreased amounts of melanin or lacks melanin completely.
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Arrector pili muscle
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is a bundle of smooth muscle tissue that is associated with individual hair follicles. When stimulated, contraction of this muscle causes hair to elevate or 'stand up' and may dimple the skin forming 'goose bumps.'
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Two types of hair
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Vellus and terminal
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Vellus hair
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thinner, softer (body hair of children and adult females)
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Terminal hair
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Thicker, coarser hair, may be darker in color than vellus hair. Hair found on the axillary (underarm) and pubic regions of males and females. This hair type is also found on the face, chest, arms, and legs of males.
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Nails
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Nails are composed of a mass of keratinized cells. Nails contain the same type of hard keratin found in hair. The exposed nail is composed of dead cells, while cell division occurs in the underlying nail bed. Nails appear pink due to the hemoglobin in the capillaries of the underlying dermis. The white, moon-shaped portion of the nail is the lunula which lies over the thick nail matrix. The cuticle is the overgrowth of the stratum corneum layer of the skin which attaches to the proximal nail fold.
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Lanugo coat
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is a layers of delicate hairs that cover a fetus. These appear approximately in the fifth month of development and are shed in approximately the seventh month of development. At this point vellus hairs replace the lanugo coat.
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