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56 Cards in this Set
- Front
- Back
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Briefly list the functions of the integumentary system.
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Itcontributes to homeostasis by protecting the body and helping regulate temperature. It also allows you to sense pleasurable, painful, and other stimuli in your external environment.
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What are the two principal layers of the skin?
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Epidermis and Dermis
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Subcutaneous layer (subQ)
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AKA hypodermis, is deep to the dermis and consists of areolar and adipose tissues. Fibers extend from the dermis and attach it to this layer, which in turn attaches to the underlying fascia, the connective tissues around muscles and bones.
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What are the four principal cell types found in the epidermis?
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keratinocytes, melanoctes, Langerhans cells, and Merkel cells
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Keratinocytes
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Constitute 90% of epidermal cells, and are arranged in four or five layers and produce the protein keratin which is a tough fibrous prtein that helps protect the skin and underlying tussues from heat, microges and chemicals. These cells also produce lamellar granules which release a water-repellant sealnt that decreases water entry andloss.
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Melanocytes
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About 8% of the epidermal cells, they develop fro the ectoderm of a developing embryo and produce the pigment melanin. Their long slender projections extend between the keratinocytes and transfer melanin granules to them.
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Melanin
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a yellow-red or brown-black pigment that contributes to skin color and absorbs damaging UV light. w/in keratinocytes, they cluster to from a protective veil over the nucleus on the sider toward the skin surface to shield the nuclear DNA from damage by UV light.
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Langerhans Cells
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Arise from red bone marrow and migrate to the epidermis where they constitute a small fraction of the epidermal cells. They participatein immune responses mounted against microbes that invade the skin and are easily damaged by UV light. They help other cells of the immune sytem recognize an invading microbe and destroy it.
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Merkel Cells
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The least numerous of the epidermal cells which are located in the deepest layer of the epidermis, where they contact the flattened process of a sensory neuron, a disc structure. These cells and their associated discs detect touch sensations.
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What are the layers of the epidermis from most superficial to deepest?
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Stratum Corneum; Stratum lucidum; stratum granulosum; stratum spinosum; stratum basale
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Stratum Basale
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The deepest layer of the epidermis, which is composed of a single row of cuboidal or columnar keratinocytes, undergo cell division to continually produce new keratinocytes. Nuclei of cells here are large and cytoplasm contains many ribosomes, a small golgi complex, a few mitochondria, and some rough ER. Cells also contain intermediate filaments, called tonofilaments which are composed of a protein that will form keratin in more superficial epidermal layers and also serve to bind the cells to each other and to the basement membrane.
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Skin Grafts
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A transfer of a patch of healthy skin taken from a donor site to cover a wound, usually from the same person to avoid tissue rejection.
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Stratum Spinosum
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Superficial to the stratum basale, arranged in 8 to 10 layers of man-sided keratinocytes fitting closely together. These cells all have the same organelles as those of the stratum basale. Under microscopic examination they seem to be covered with thorny spines but really they are rounded in living tissue. This layer provides strength and flexibility to the skin.
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Stratum Granulosum
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At the middle of the epidermis, consists of three to five layers of flattened keratinocytes that are undergoing apoptosis (an orderly genetically programmed cell death in which the nucleus fragments before the cells die). Nuclei and other organellesof these cells begin to degenerate, and tonofilaments become more apparent.
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Keratohyalin
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A darkly staining granule found in the stratum granulosum, which converts the tonofilaments into keratin.
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lamellar granules
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Present in the keratinocytes in the stratum granulosum, are membrane-enclosed and release a lipid-rich secretion which fills the spaces between cells of the top layers of the epidermis.
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Stratum lucidum
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Present only in the thick skin of areas such as the fingertips, palms, and soles. It consists of three to five layers of flattened clear, dead keratinocytes that contain large amounts of keratin and thickened plasma memberanes.
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Stratum Corneum
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Most superficial layer of epidermis, consists of 25 - 30 layers of flattened dead keratinocytes which are continuously shed and replaced by cells from the deeper strata. Interior of cells ismostly keratin and between the cells are lipids fro lamellar granules that helpmake this layer an effective water-repellent barrier. Help protect deeper layers from injury and microbial invasion.
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Callus
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An abnormal thickening of the stratum corneum which occurs due to constant exposure of skin to friction.
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Keratinization
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The process in which newly formed cells in the stratum basale are slowly pushed to the surface and accumulate more and more keratin as they move from one epidermal layer to the next.
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Epidermal growth factor (EGF)
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The mechanisms which regulate the growth associated with keratinization, are not well understood, but hormone-like proteins play a role.
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Dandruff
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An excessive amount of keratinized cells shed from the skin of the scalp
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Dermis
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The second, deeper part of the skin, composed of a strong connective tissue containing collagen and elastic fibers. This woven network of fibers has great tensile strength (resists pulling or stretching forces). This layer also has the ability to stretch and recoil easily, and the few cells present here are fibroblasts, with some macrophages and a few adipocytes near its boundary with the subQlayer.
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Papillary Region
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The superficial region of the dermis, makes up about one-fifth of the thickness of the total layer, and consists of areolar connecive tissue containing thin collagen and fine elastic fibers.
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Dermal Papillae
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Small fingerlike structure that project into the undersurface of the epidermis and greatly increase the surface area of the papillary region. Some of these nipple shaped structures contain capillary loops or blood vessels.
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Meissner Corpuscles
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Corpuscles of touch, tactile receptors within some dermal papillae are nerve endings that are sensitive to touch.
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Free nerve endings
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Dendrites that lack any apparent structural specialization. Initiate signals that give rise to senstions of warmth, coolness, pain, tickling, and itching.
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Reticular Region
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Deeper layer of the dermis, is attached to the subcutaneous layer, and consists of dense irregular connective tissue containing fibroblasts, bundles of collagen, and some coarse elastic fibers which interlace in a netlike manner. A few adipose cells, hair follicles, nerves, sebaceous glands, and sudoriferous glands occupy the spaces between fibers.
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Extensibility & Elasticity
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Ability to stretch; Ability to return to original shape after stretching. Collagen and elastic fibers in the reticular region of the dermis provide the skin with these properties.
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Lines of cleavage
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Tension lines in the skin indicate the predominant direction of underlying collagen fibers. Important to plastic surgeons, because an incision parallel to these lines will heal with only a fine scar but an incision running across the rows of fibers will gape open and result in a big nasty scar.
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Epidermal Ridges
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A series of ridges and grooves produced during the third month of fetal devlopment as downward projections of the epidermis into the dermis between the dermal papillae of the papillary region. They increase the surface area of the epidermis, thus increasing the grip of the hand or foot by increasing friction.
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Epidermal Ridges and dermal papillae interaction.
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They fit together to form an extremelystrong junction between the two layers. This jigsaw puzzle-like connection strengthens the skins against shearing forces that attempt to separate the epidermis from the dermis.
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Structural Basis of Skin Color
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The amount of melanin causes the skin's color to vary from pale yellow to reddish brown to black.
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Melanosome and exposure to sunlight
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The organelle which produces melanin. Melanin absorbs UV radiation and prevents damage to DNA in epidermal cells and neutralizes free radicals that form in the skin following damage by UV radiation. Production of melanin increases with exposure to UV rays and gives the skin a tanned appearance. Too much exposure to UV light causes skin cancer.
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Cyanotic
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When skin appears bluish because someone has stopped breathing
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Jaundice
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due to a buildup of the yellow pigment bilirubin in the skin, skin retains a yellowish appearance and this usually indicates liver disease
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Erythema
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Redness of the skin caused by engorgement of capillaries in the dermis with blood due to skin injury, exposure to heat, infection, inflammation,or allergic reactions.
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Pallor
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Paleness of the skin,may occur in conditions such as shock and anemia.
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Melanin and skin color
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Dark-skinned individuals have large amounts of melanin in the epidermis, and light skinned individuals have little melanin in the epidermis.
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Albinism
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The inherited inability of an individual to produce melanin.
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Hairs
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present on most skin surfaces except the palms, palmar surfaces of the fingers, the soles, and plantar surfaces of the feet. On the head it guards the scalp from injury and the sun's rays and decreases heat loss from the scalp.
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Shaft
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the superficial portion of the hair which projects above the surface of the skin
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Root
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The portion of the hair deep to the shaft that penetrates into the dermis and sometimes into the subcutaneous layer.
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3 Concentric Layers of the hair shaft and root
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medulla, cortex and cuticle
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inner medulla
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may be lacking in thinner hair, is composed of two or three rows of irregularly shaped cells
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middle cortex
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forms the major part of the shaft and consists of elongated cells
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cuticle of the hair
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the outermost layer, consists of a single layer of thin, flat cells that are the most heavily keratinized. In the shaft they are arranged like shingles on the side of a house with their free edges pointing toward the end of the hair.
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hair follicle
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Surrounding the root of the hair, is made up of an external root sheath and an internal root sheath together referred to as an epithelial root sheath
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Epithelial Root Sheath
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External is a downward continuation of the epidermis, and iternal is produced by the matrix and forms a cellular tubular sheath of epithelium between the external root sheath and the hair.
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Dermal root sheath
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The dense dermis surrounding the hair follicle
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Bulb
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Consists of the base of each hair follicle and its surrounding dermal root sheath, is an onion-shaped structure.
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Bulb
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Consists of the base of each hair follicle and its surrounding dermal root sheath, is an onion-shaped structure.
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Papilla of the hair
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Housed within the bulb, is a nipple-shaped indentation which contains areolar connective tissue and many blood vessels that nourish the growing hair follicle
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Papilla of the hair
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Housed within the bulb, is a nipple-shaped indentation which contains areolar connective tissue and many blood vessels that nourish the growing hair follicle
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Hair matrix
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within the bulb, a germinal layer of cells which arise from the stratum basale, the site of cell division. Hence, these cells are responsible for the growth of existing hairs and they produce new hairs when old hairs are shed. A replacement process which occurs within the same follicle
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Hair matrix
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within the bulb, a germinal layer of cells which arise from the stratum basale, the site of cell division. Hence, these cells are responsible for the growth of existing hairs and they produce new hairs when old hairs are shed. A replacement process which occurs within the same follicle
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