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137 Cards in this Set
- Front
- Back
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Describe the anatomy of Skin aka Cutaneous membrane aka Integument
Describe the 2 main parts |
-largest organ in the body by SA and weight
Epidermis -superficial, thinner portion -made up of epithelial tissue Dermis -deeper, thicker -made up of connective tissue |
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What does the integumentary system include?
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nails
sweat glands oil glands skin hair sensory receptors |
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What are the functions of the integumentary system?
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1. Regulates body temperature
2. Stores blood 3. Protects body from external environment 4. Detects cutaneous sensations 5. Excretes and absorbs substances 6. Synthesizes vitamin D |
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Describe the subcutaneous (subQ) layer aka hypodermis
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-aka hypodermis = below dermis
=continuous sheet of areolar connective tissue and adipose tissue -between the dermis of the skin and the deep fascia of the muscles =storage depot for fat -contains large blood vessels -contains pacinian (lamellated) corpuscles (nerve ending sensitive to P) |
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What is the epidermis composed of?
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-composed of keratinized stratified squamous epithelium
-contains 4 principal types of cells: keratinocytes (90%), melanocytes (8%), Langerhans cells, and Merkel cells (least) (KMLM…kerits, melons, lemons, merits) |
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Describe the arrangement of keratinocytes and what they produce
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-arranged in 4 or 5 layers
-produce the protein keratin and lamellar granules |
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What is keratin?
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-tough, fibrous protein
-helps protect the skin and underlying tissues from heat, microbes, and chemicals |
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What do lamellar granules produce?
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-a water-repellent sealant >> decreases water entry and loss >> inhibits the entry of foreign materials
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Where do melanocytes develop from?
What do they produce? |
Develop from ectoderm of a developing embryo
Produce the pigment melanin |
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Describe the structure and appearance of melanin and where are they located?
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-long, slender projections
-extend between the keratinocytes and transfer melanin granules to them -yellow-red or brown-black pigment |
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What is the function of melanin?
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-contributes to skin color
-absorbs damaging UV light -melanin granules form protective veil over nucleus inside keratinocytes >>shield the nuclear DNA from damage by UV light ***melanin granules effectively protect keratinocytes but melanocytes themselves are susceptible to damage by UV light |
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Where do Langerhans cells develop from and where do they migrate to?
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-arise from red bone marrow and migrate to the epidermis
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What are the functions of Langerhans cells?
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-participate in immune responses against microbes that invade the skin
-help other cells of the immune system recognize an invading microbe and destroy it ***are easily damaged by UV light. |
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Where are merkel cells located and what do they contact?
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-in the deepest layer of the epidermis
-makes contact with a tactile (pertaining to touch) disc called a Merkel disk (sensory neuron), which functions in touch |
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Name the 4 strata/layers of the epidermis in most regions of the body aka thin skin
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stratum basale
stratum spinosum stratum granulosum stratum corneum aka thin skin |
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Name the 5 strata/layers of thick skin and where can it be found?
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stratum basale
stratum spinosum stratum granulosum stratum lucidum thick stratum corneum -fingertips, palms, and soles |
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Which epidermal layer includes stem cells that continually undergo cell division?
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Stratum basale
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Describe the structure of stratum basale aka stratum germinativum and what it is composed of?
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-deepest later of epidermis
-single row of cuboidal/columnar keritanocytes -some cells = stem cells >> undergo cell division to continually produce new keratinocytes -Melanocytes, Merkel cells, Merkel discs are scattered among the keratinocytes |
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Why is the stratum basale also called the stratum germinativum?
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***aka stratum germinativum (germ = sprout) to indicate its role in forming new cells.
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Describe the organelles of keratinocyte cells in the stratum basale
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-nuclei large
-cytoplasm contains many ribosomes -small Golgi complex -a few mitochondria -some rough ER -cytoskeleton have tonofilaments (scattered intermediate filaments) |
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What are tonofilaments composed of and what do they form?
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-composed of a protein that will form keratin in more superficial epidermal layers
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What do tonofilaments attach to and what are the functions of these attachments?
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-attach to desmosomes
>>bind cells of the stratum basale to each other and to the cells of the adjacent stratum spinosum -attach to hemidesmosomes >>bind keratinocytes to the basement membrane positioned between the epidermis and the dermis |
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What is a skin graft?
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=the transfer of a patch of healthy skin taken from a donor site to cover a wound
-autograft >> To avoid tissue rejection, the transplanted skin is usually taken from the same individual -isograft >> from an identical twin |
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Where is stratum spinosum located?
What is this layer composed of and How is it arranged? |
-Superficial to the stratum basale
-arranged in 8 to 10 layers of many-sided keratinocytes fitting closely together -consists of bundles of tonofilaments inserting into desmosomes = spiny projections in a prepared tissue section >> tightly join cells to one another -Langerhans cells -projections of melanocytes |
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What is the function of the arrangement of tonofilaments, keratinocytes, and desmosomes in stratum spinosum?
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-arrangement provides both strength and flexibility to the skin
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What is the stratum granulosum composed of?
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-3 to 5 layers of flattened keratinocytes that are undergoing apoptosis
>> nuclei and other organelles of these cells begin to degenerate, and tonofilaments become more apparent. ***this layer marks the transition between the deeper, metabolically active strata and the dead cells of the more superficial strata |
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What is the distinctive feature of cells in the stratum granulosum?
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=presence of darkly staining granules of a protein called keratohyalin (converts the tonofilaments into keratin)
=presence of membrane-enclosed lamellar granules (release a lipid-rich secretion) |
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What is the function of keratohyalin in the keratinocytes of stratum granulosum?
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-converts tonofilaments into keratin
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What is the function of the lipid-rich secretion released by lamellar granules in stratum granulosum?
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-fills the spaces between cells of the stratum granulosum, stratum lucidum, and stratum corneum
-acts as a water-repellent sealant >> retarding loss and entry of water and entry of foreign materials |
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Where is stratum lucidum (lucid = clear) present?
What is it composed of? |
-present only in thick skin (fingertips, palms, and soles)
-consists of 3-5 layers of flattened clear, dead keratinocytes that contain large amounts of keratin and thickened plasma membranes |
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What composes the stratum corneum (corne = horn/horny)?
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~25 to 30 layers of flattened dead keratinocytes (contain mostly keratin)
>> continuously shed and replaced by cells from the deeper strata -lipids from lamellar granules >> layer = water-repellent barrier |
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What are the functions of the multiple layers of dead cells of the stratum corneum?
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-protect deeper layers from injury and microbial invasion
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What forms from the constant exposure of skin to friction?
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-stimulates the formation of a callus (abnormal thickening of the stratum corneum)
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Describe keratinization and how long does it take in an average epidermis?
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Newly formed cells in the stratum basale are slowly pushed to the surface. As the cells move from one epidermal layer to the next, they accumulate more and more keratin
Then they undergo apoptosis >> Eventually keratinized cells slough off and are replaced by underlying cells that in turn become keratinized -4 weeks |
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Which layer of epidermial cells is closest to the blood vessels and why?
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-stratum basale >> receive most of the nutrients and oxygen
>> these epidermal cells are most active metabolically and continuously undergo cell division to produce new keratinocytes |
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When does the rate of cell division in the stratum basale increase?
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-when the outer layers of the epidermis are stripped away (ie. abrasions and burns
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What proteins play a role in keratinization?
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-hormone-like proteins such as epidermal growth factor (EGF)
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What is psoriasis?
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=common and chronic skin disorder >> keratinocytes divide and move more quickly than normal from the stratum basale to the stratum corneum
>> shed prematurely (7-10 days vs 4 weeks) -immature keratinocytes make an abnormal keratin, which forms flaky, silvery scales at the skin surface, most often on the knees, elbows, and scalp (dandruff) |
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What is the Dermis (2nd, deeper part of skin) composed of and what is embedded into it?
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-composed of a strong connective tissue
>>contains woven network of collagen and elastic fibers >> tensile strength (resists pulling or stretching forces) and recoils easily -composed of fibroblasts with some macrophages, and a few adipocytes -blood vessels, nerves, glands, and hair follicles embedded into dermal layer |
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Name the two parts of the dermis
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-superficial papillary region (1/5 of total layer)
-deeper reticular region |
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What does the dermal superficial papillary region consist of?
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-areolar connective tissue >> contains thin collagen and fine elastic fibers
-dermal papillae >> increases SA >> small, fingerlike structures >> project into undersurface of the epidermis >>some contain capillary loops (blood vessels) >> some contain tactile receptors (Meissner corpuscles) and free nerve endings (sensations of warmth, coolness, pain, tickling, and itching) |
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What is the reticular region attached to and what does it consist of?
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-attached to the subcutaneous layer
-consists of dense irregular connective tissue containing fibroblasts, bundles of collagen, and some coarse elastic fibers -a few adipose cells, hair follicles, nerves, sebaceous (oil) glands, and sudoriferous (sweat) glands |
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What properties do the combination of collagen and elastic fibers in the reticular region provide the skin with?
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Strength
extensibility (ability to stretch) elasticity (ability to return to original shape after stretching) |
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Define striae
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(= streaks)
=stretch marks |
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What do lines of cleavage (tension lines) indicate and how are they applicable in plastic surgery?
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Indicate predominant direction of underlying collagen fibers
-a surgical incision running parallel to the collagen fibers = a fine scar -a surgical incision made across the rows of fibers disrupts the collagen = broad, thick scar |
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Where are epidermal ridges found and when are they produced?
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-surfaces of palms, fingers, soles, and toes
-produced during the third month of fetal development |
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What are the functions of epidermal ridges?
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-increase the surface area of epidermis
-increase the grip of the hand or foot by increasing friction -basis for identification: sweat gland ducts on tops of epidermal ridges as sweat pores, the sweat and ridges form fingerprints (or footprints) |
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What is the study of the patterns of epidermal ridges?
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dermatoglyphics (glyphe = carved work).
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What are the functions of dermal papillae?
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-form epidermal ridges
-increase the surface contact between the dermis and epidermis >> increases contact with small blood capillaries >> important source of nutrition for overlying stratum basale and keratinocytes within it |
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What strengthens the skin against shearing forces (forces that laterally shift in relation to each other) that keep the dermis and the epidermis together?
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Dermal papillae fit together with the complementary epidermal ridge to form an extremely strong junction between the two layers >> jigsaw puzzle–like connection
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What are the 3 pigments that impart a wide variety of colours to skin?
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Melanin (in hair)
-pheomelanin (yellow to red) -eumelanin (brown to black) Hemoglobin (red) Carotene (yellow-orange) |
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What are melanin-producing cells calls are where in the body are they predominant?
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Melanocytes
Most plentiful in the epidermis of the penis, nipples of the breasts, area just around the nipples (areolae), face, and limbs mucous membranes |
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What determines skin color?
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due mainly to the amount of pigment the melanocytes produce and transfer to keratinocytes
NOT the number of melanocytes >> # same in all people (ie. Freckles and age/liver spots = accumulations of melanin) |
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What is a mole aka nevus?
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Round, flat, or raised area that represents a benign localized growth of melanocytes
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What is the amino acid, the enzyme, and the organelle used in the synthesis of melanin from melanocytes?
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AA: tyrosine
Enzyme: tyrosinase Melanosome |
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What increases the enzymatic activity within melanosomes and thus increases melanin production?
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UV light
>> Both the amount and darkness of melanin increase >> tan |
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How does melanin protect the body?
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Melanin absorbs UV radiation, prevents damage to DNA in epidermal cells, and neutralizes free radicals that form in the skin following damage by UV radiation
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How is a tan lost?
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when the melanin-containing keratinocytes are shed from the stratum corneum
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What foods have Carotene (carot = carrot)?
What is carotene a precursor of? |
-gives egg yolk and carrots their color
=precursor of vitamin A >> used to synthesize pigments needed for vision |
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Where is carotene stored?
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-stratum corneum
-fatty areas of the dermis -subcutaneous layer (from excessive dietary intake) |
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What is Albinism (albin- = white)
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=inherited inability of an individual to produce melanin
-Most albinos have melanocytes that are unable to synthesize tyrosinase >> Melanin is missing from their hair, eyes, and skin. |
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What is Vitiligo?
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=the partial or complete loss of melanocytes from patches of skin produces irregular white spots
>> loss of melanocytes may be related to an immune system malfunction in which antibodies attack the melanocytes |
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What is Jaundice? (jazund- = yellow) and what is it caused by?
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-buildup of the yellow pigment bilirubin in the skin
-yellowish appearance to the skin and the whites of the eyes, and usually indicates liver disease |
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What is Erythema (eryth = red) and what causes it?
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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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What is Pallor?
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=paleness of the skin, may occur in conditions such as shock and anemia
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What determines the thickness and pattern of hair distribution?
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Genes
hormones |
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What are the functions of hair (aka pilus)?
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-sensing light touch
-protection |
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What is hair composed of?
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Each hair composed of columns of dead, keratinized epidermal cells
>>bonded together by extracellular proteins |
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What are the two sections of a hair? Name their layers
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shaft
root Both consist of 3 concentric layers of cells: medulla, cortex, and cuticle |
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Describe the shape of the cells of each layer on a pilus
inner medulla (may be lacking in thinner hair) |
-composed of 2 or 3 rows of irregularly shaped cells.
middle cortex -forms major part of the shaft -consists of elongated cells cuticle of the hair -outermost layer -consists of a single layer of thin, flat cells that are the most heavily keratinized -on shaft: arranged like shingles on the side of a house |
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What is the hair follicle made up of?
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Epithelial root sheath: external and internal root sheath
Dermal root sheath (=dense dermis surrounding hair follicle) |
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What is the internal root sheath produced by and what does it form?
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-produced by matrix
-forms a cellular tubular sheath of epithelium between the external root sheath and the hair |
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What does the papilla of the hair contain?
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-contains areolar connective tissue
-many blood vessels that nourish the growing hair follicle |
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Where are the hair matrix cells produced?
What are they responsible for and what do they produce? |
-stratum basale
-responsible for growth of existing hairs -produce new hairs when old hairs shed -produce cells of internal root sheath |
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What are arrector pili and what do they do?
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Smooth muscles attached to hairs; contraction pulls the hairs into a vertical position, resulting in “goose bumps.”
-its normal position: hair at angle to skin’s surface >>under stress: autonomic nerve endings stimulate the arrector pili muscles to contract >> pulls the hair shafts perpendicular to the skin surface |
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Define hair root plexuses and describe their function
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A network of dendrites arranged around the root of a hair as free or naked nerve endings
-generate nerve impulses when a hair shaft is moved |
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Why does it hurt when you pluck a hair out but not when you have a haircut?
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Plucking a hair stimulates hair root plexuses in the dermis, some of which are sensitive to pain. Because the cells of a hair shaft are already dead and the hair shaft lacks nerves, cutting hair is not painful
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What are the 3 stages in a hair follicle’s growth cycle?
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growth stage, a regression stage, and a resting stage
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Describe the growth (anagen) stage in the growth cycle of a hair follicle
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-cells of the hair matrix divide >> new cells from the hair matrix added to base of hair root >> hair grows longer (cells keratinize and die)
~2-6 years |
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Describe the regression (catagen) stage in the growth cycle of a hair follicle
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-when hair matrix cells stop dividing, hair follicle atrophies (shrinks), and hair stops growing
~2-3 weeks |
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Describe what happens after the resting (telogen) stage in the growth cycle of a hair follicle and how long does the resting stage last?
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-old hair root falls out or is pushed out of the hair follicle >> new hair begins to grow in its place
-3 months |
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Define Alopecia and what causes it?
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=partial or complete lack of hair
-may result from genetic factors, aging, endocrine disorders, chemotherapy, or skin disease |
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Define lanugo and when does it develop? What is it later replaced with?
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=fine, non-pigmented, downy hairs that cover the fetus
-5 months after fertilization -replaced with terminal and vellus hairs |
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Define terminal hair
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-long, coarse, heavily pigmented hairs
-replaces the lanugo of eyebrows, eyelashes, and scalp >>develop prior to birth -replaces vellus hairs in axillae (armpits), face, chest, limbs, pubic regions >>develop at puberty from androgens (hormones) |
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Define vellus hairs
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-lanugo of the rest of the body are replaced by vellus hairs aka “peach fuzz” =short, fine, pale hairs that are barely visible to the naked eye
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What causes hair colour? And where is it synthesized?
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-amount and type of melanin in keratinized cells
-in matrix of bulb >> Melanin synthesized by melanocytes >> passes into cells of the cortex and medulla of the hair |
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What pigments give dark, blond/red, white, and gray hair?
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Dark-colored hair contains mostly eumelanin
blond and red hair contain variants of pheomelanin gray hair = progressive decline in melanin production, contains only a few melanin granules White hair = lack of melanin and the accumulation of air bubbles in the shaft. |
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What is hirutism?
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Condition of excessive body hair
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What are Sebaceous Glands?
What do they secrete? |
=simple, branched acinar exocrine glands in the dermis of the skin, almost always associated with a hair follicle
-secretes sebum |
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How are sebaceous glands different on parts of the body? Where on the body are sebaceous glands found and not found?
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-secreting portion lies in the dermis and usually opens into the neck of a hair follicle
-In some locations (ie. lips, glans penis, labia minora, and tarsal glands of the eyelids) sebaceous glands open directly onto the surface of the skin -Absent in the palms and soles -small in most areas of the trunk and limbs -large in skin of the breasts, face, neck, and superior chest. |
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What is sebum and what are its functions?
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=a mixture of triglycerides, cholesterol, proteins, and inorganic salts
-coats surface of hairs >> helps keep them from drying and becoming brittle -prevents excessive evaporation of water from the skin, keeps the skin soft and pliable, and inhibits the growth of some (but not all) bacteria |
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How do sebaceous glands change from childhood to puberty?
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Childhood
-sebaceous glands are relatively small and inactive Puberty -androgens from the testes, ovaries, and adrenal glands stimulate sebaceous glands to grow in size and increase their production of sebum |
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What is acne?
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= inflammation of sebaceous glands
-occurs predominantly in sebaceous follicles that have been colonized by bacteria, some of which thrive in the lipid-rich sebum >> cystic acne: infection may cause a cyst/sac of connective tissue cells to form >> can destroy and displace epidermal cells >> scar |
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What are sudoriferous glands?
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=An apocrine or eccrine exocrine gland in the dermis or subcutaneous layer that produces perspiration. Also called a sweat gland
-release sweat, or perspiration, into hair follicles or onto the skin surface through pores |
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What are the two main types of sweat/sudoriferous glands? What is the 3rd type of sudorifurous gland?
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-eccrine and apocrine
>>based on their structure, location, and type of secretion -ceruminous gland |
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What are Eccrine / merocrine sweat glands and where on the body are they predominant?
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(eccrine = secreting outwardly)
= simple, coiled tubular glands -much more common than apocrine sweat glands -distributed at most regions of the body, especially in forehead, palms, and soles >> NOT in lips, nail beds of the fingers and toes, glans penis, glans clitoris, labia minora, and eardrums |
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Which layer are the secretory portions of eccrine sweat glands located?
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-mostly in the deep dermis (sometimes in upper subcutaneous layer)
-excretory duct projects through the dermis and epidermis and ends as a pore at the surface of the epidermis |
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What is sweat composed of?
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-water, ions (mostly Na+ and Cl-), urea, uric acid, ammonia, amino acids, glucose, and lactic acid.
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What are the functions of eccrine sweat glands?
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-main function: help regulate body temperature through evaporation (thermoregulation >> thermoregulatory sweating)
>>As sweat evaporates, large quantities of heat energy leave the body surface -eliminates waste (urea, uric acid, and ammonia) -emotional sweating/cold sweat (fear, embarrassment) |
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What is insensible and sensible perspiration?
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Insensible: Sweat that evaporates from the skin before it is perceived as moisture
Sensible: Sweat that is excreted in larger amounts and is seen as moisture on the skin |
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What are Apocrine sweat glands? (apo- = separated from) Where on the body are they found?
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-also simple, coiled tubular glands
-cells secrete via exocytosis -found mainly in the skin of the axilla (armpit), groin, areolae (pigmented areas around the nipples) of the breasts, and bearded regions of the face in adult males |
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Which epithelial layer are secretory portions of apocrine sweat glands found?
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-located mostly in the subcutaneous layer
-excretory duct opens into hair follicles |
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Compare eccrine sweat and apocrine sweat
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apocrine sweat
-slightly viscous -appears milky or yellowish in color -contains the same components as eccrine sweat plus lipids and proteins -odorless unless interacts with bacteria on skin >> body odor |
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When are eccrine and apocrine sweat glands active?
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Apocrine sweat glands
-function at puberty -during sexual activites Eccrine sweat glands -Function after birth -during thermoregulatory sweating Both active during emotional sweating |
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What are ceruminous glands? Which epithelial layer are they located?
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=A modified sudoriferous (sweat) gland in the external auditory meatus that secretes cerumen (ear wax)
-in the subcutaneous layer, deep to sebaceous glands |
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Where do the excretory ducts of ceruminous glands open up?
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-open either directly onto the surface of the external auditory canal (ear canal) or into ducts of sebaceous glands
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What is the function of Cerumen
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-cerumen together with hairs in the external auditory canal, provides a sticky barrier that impedes the entrance of foreign bodies and insects
-also waterproofs the canal and prevents bacteria and fungi from entering cells |
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What are nails composed of and where does it develop from?
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-composed largely of keratin (packed, dead, keratinized epidermal cells)
-develops from epidermis of skin |
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What do nails consist of?
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nail body (plate)
a free edge (white) a nail root (buried in folded skin) lunula (white, thickened epithelium under nail body in crescent moon shape) hyponychium (aka nail bed, thickened region of stratum corneum, secures nail to fingertip) eponychium (aka cuticle = narrow band of epidermis, stratum corneum) nail matrix (beneath body and root, its superficial cells divide by mitosis to produce growth) |
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List the functions of skin
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Thermoregulation
Blood storage Protection Cutaneous sensations (touch, pressure, vibration, tickling, warm, cold, pain) Excretion and absorption Synthesis of Vitamin D (UV rays activate precursor mlcl >> enzymes in kidneys and liver modify to produce calcitriol (most active form of Vitamin D, hormones, helps absorb calcium into blood from GI tract) |
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List the components of skin and their functions that protect the body
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-Keratin protects from microbes, abrasion, heat, and chemicals
-Keratinocytes resist invasion by microbes -Lipids released by lamellar granules inhibit evaporation of water from the skin surface >> guards against dehydration >> retard entry of water across the skin surface during showers and swims -Sebum from the sebaceous glands keeps skin and hairs from drying out and contains bactericidal chemicals that kill surface bacteria -Acidic pH of perspiration retards the growth of some microbes -Melanin pigment helps shield against damaging UV light -Langerhans cells alert the immune system to the presence of potentially harmful microbial invaders by recognizing and processing them -Macrophages in the dermis phagocytize bacteria and viruses that manage to bypass the Langerhans cells of the epidermis |
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What is the difference between epidermal wound healing and deep wound healing?
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Epidermal wound healing occurs following wounds that affect only the epidermis
Deep wound healing occurs following wounds that penetrate the dermis and subcutaneous layer (multiple tissue layers need to be repaired, more complex process) |
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Describe the process of epidermal wound healing
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Basal cells of epidermis surrounding the wound contact basement membrane >> cells enlarge and migrate across wound >> cells appear to migrate as a sheet until advancing cells from opposite sides of wound meet >> When epidermal cells encounter one another, they stop migrating due to contact inhibition (cellular response) >> Migration of the epidermal cells stops completely when each is finally in contact with other epidermal cells on all sides
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Describe the 4-phase process of deep wound healing
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Inflammatory phase
Migratory phase Proliferative phase Maturation phase. *last 3 phases repair the wound |
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Describe the process of the Inflammatory phase in deep wound healing
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blood clot forms >> loosely unites wound edges >> inflammation helps eliminate microbes, foreign material, and dying tissue in preparation for repair >> vasodilation and increased permeability of blood vessels associated with inflammation enhance delivery of phagocytic WBCs (=neutrophils), monocytes (develop into macrophages that phagocytize microbes) and mesenchymal cells (develop into fibroblasts)
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Describe the process of the Migratory phase in deep wound healing
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-clot becomes a scab
-epithelial cells migrate beneath scab to bridge the wound -Fibroblasts migrate along fibrin threads >> synthesize scar tissue (collagen fibers & glycoproteins) -damaged blood vessels begin to regrow -granulation tissue fills wound |
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Describe the process of the Proliferative phase in deep wound healing
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-extensive growth of epithelial cells beneath the scab
-deposition by fibroblasts of collagen fibers in random patterns -continued growth of blood vessels |
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Describe the process of the maturation phase in deep wound healing
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-scab sloughs off once the epidermis has been restored to normal thickness
-Collagen fibers become more organized -fibroblasts decrease in number -blood vessels are restored to normal |
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Fibrosis
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=process of scar tissue formation is called fibrosis
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Define hypertrophic scar
Define keloid aka cheloid scar |
Hypertrophic: A scar that remains within the boundaries of the original wound
Keloid: a scar that extends beyond the boundaries into normal surrounding tissues |
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What is the difference between scar tissue and normal skin?
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Scar tissue’s collagen fibers are more densely arranged
-decreased elasticity -fewer blood vessels -may or may not contain the same number of hairs, skin glands, or sensory structures as undamaged skin ***Because of the arrangement of collagen fibers and the scarcity of blood vessels, scars usually are lighter in color than normal skin |
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What causes skin cancer?
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UVA rays (longer wave-lengths, results in sun tan, depress immune system) and UVB rays (shorter wave-lengths, responsible for most of tissue damage >> production of oxygen free radicals that disrupt collagen and elastic fibers, causes sun burns)
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What is the most common type of skin cancer?
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Basal cell carcinoma is the most common type of skin cancer.
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Describe the two types of nonmelanoma skin cancer
Which epithelial layers do they arise from and do they metastasize? |
Basal cell carcinoma
-arise from cells in the stratum basale of epidermis -rarely metastasize Squamous cell carcinomas -arise from squamous cells of epidermis -has a variable tendency to metastasize >>Most arise from preexisting lesions of damaged tissue on sun-exposed skin |
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What do malignant melanomas arise from? What is causing the increase of diagnoses? Do they metastasize?
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-arise from melanocytes
-increase from more people are spending more time in the sun and in tanning beds -metastasize rapidly and can kill a person within months of diagnosis |
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Specify the acronym ABCD for early warning signs of malignant melanoma
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A is for asymmetry; lack symmetry
B is for border; irregular, indented, scalloped, indistinct borders C is for color; uneven coloration, may contain several colors D is for diameter; ordinary moles = smaller than size of a pencil eraser ***Once a malignant melanoma has the characteristics of A, B, and C, it is usually larger than 6 mm |
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List the risk factors for skin cancer
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Skin type
Sun exposure Family history Age Immunological status What is a burn? =tissue damage caused by agents that destroy the proteins in skin cells |
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What is a first-degree burn?
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-involves only the epidermis
-characterized by mild pain and erythema (redness) but no blisters -Skin functions remain intact -healing accompanied by flaking or peeling -ie. mild sunburn ***First- and second-degree burns are collectively referred to as partial-thickness burns. |
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What determines the seriousness of a burn?
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- depth and extent of the area involved, the individual's age, and general health
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What is a second-degree burn?
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-destroys the epidermis and part of the dermis
-Some skin functions are lost -characterized by redness, blister formation, edema, pain -Associated structures (hair follicles, sebaceous glands, sweat glands) usually not injured -If no infection, heal without skin grafting ~3 to 4 weeks -scarring may result ***First- and second-degree burns are collectively referred to as partial-thickness burns |
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What is a third-degree burn / full-thickness burn?
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-destroys epidermis, dermis, and subcutaneous layer
-Most skin functions are lost -characterized by marked edema, numb burned region (destroyed sensory nerve endings) -Regeneration occurs slowly -much granulation tissue forms before being covered by epithelium -Skin grafting may be required to promote healing and to minimize scarring |
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What is more of a threat to life – the local or systemic effects of a major burn? And why?
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systemic effects
(1) a large loss of water, plasma, and plasma proteins, which causes shock (2) bacterial infection (3) reduced circulation of blood (4) decreased production of urine (5) diminished immune responses |
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What is the rule of nines?
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=A quick rule for estimating the surface area affected by a burn in an adult
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Define a Cold sore
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A lesion, usually in oral mucous membrane, caused by Type 1 herpes simplex virus (HSV) transmitted by oral or respiratory routes. The virus remains dormant until triggered by factors such as ultraviolet light, hormonal changes, and emotional stress. Also called a fever blister
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Define Eczema
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An inflammation of the skin characterized by patches of red, blistering, dry, extremely itchy skin. It occurs mostly in skin creases in the wrists, backs of the knees, and fronts of the elbows. It typically begins in infancy and many children outgrow the condition. The cause is unknown but is linked to genetics and allergies
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Define Hives
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Reddened elevated patches of skin that are often itchy. Most commonly caused by infections, physical trauma, medications, emotional stress, food additives, and certain food allergies. Also called urticarial
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Wart
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Mass produced by uncontrolled growth of epithelial skin cells; caused by a papillomavirus. Most warts are noncancerous
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