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65 Cards in this Set
- Front
- Back
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The Integumentary System
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Contains the skin, hair, nails, oil and sweat glands, and sensory receptors
Maintains body temperature, protects, provides sensory information about surrounding environment |
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Skin
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The body’s largest organ
About 16% of body weight Covers the external surface of body About 2.0 square meters Two layers: Epidermis Dermis Under the dermis is hypodermis or subcutaneous layer (not part of the skin) |
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The Epidermis
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A keratinized stratified squamous epithelium
Contains four different cells Contains five layers Has several functions |
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Cells of the Epidermis
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Keratinocyte
Melanocyte Langerhans cell Merkel cell |
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Keratinocyte-Epidermis
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About 90% of all epidermal cells
Secretions: Keratin: tough, fibrous proteins to protect skin Lamellar bodies: contain a lipoprotein that fills spaces between cells; acts as a waterproofing substance |
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Melanocyte-Epidermis
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About 8% of epidermal cells
Contains melanin granules Melanin granules pinch away from melanocyte and are phagocytized by keratinocyte Melanin absorbs UV radiation |
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Langerhans Cell-Epidermis
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About 2% of epidermal cells
Participates in immune responses Helps other cells of the immune system recognize the invading microbe and destroy it Are easily damaged by UV light |
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Merkel Cell-Epidermis
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The least numerous of the epidermal cells
Located in the deepest layer of epidermis A sensory cell Responds to touch sensation |
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Layers of the Epidermis
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From deep to superficial:
Stratum basale Stratum spinosum Stratum granulosum Stratum lucidum Stratum corneum |
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Stratum Basale-Epidermis layers
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Deepest layer of the epidermis
A single layer of cuboidal or columnar keratinocyte Some cells are stem cells and undergo cell division to produce new keratinocytes and replace dead cells |
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Stratum Spinosum-Epidermis layers
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Multiple layers of keratinocytes located above the stratum basale
Cells are connected by intercellular spines Langerhans cells are present in this layer |
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Stratum Granulosum-Epidermis layers
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A few layers of flattened keratinocytes that have stored keratohyalin granules and lamellar bodies granules in their cytoplasm
Cells are undergoing apoptosis |
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Stratum Lucidum-Epidermis layers
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A few layers of flattened dead/or dying keratinocytes
They have lost cellular organelles and appear clear Contain large amounts of keratin Only in thick skin of areas such as finger tips, palms, soles |
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Stratum Corneum-Epidermis layers
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Keratinocytes in this layer are dead
What remains of these cells are numerous layers of keratin protein |
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The Dermis
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Two regions:
Papillary region: just beneath the epithelium Reticular region: below the papillary layer |
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Papillary Region of the Dermis
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Composed of loose Areolar CT with many sensory nerve endings
Contains extensions called dermal papilla Papilla increase the surface contact between dermis and epidermis |
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Fingerprints
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Epidermal ridges: downward projections of the epidermis into the dermis
To increase friction The unique pattern of epidermal ridges most prominent on the fingers and toes Patterns are unique for each individual, including identical twins |
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Reticular Region of the Dermis
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Composed of dense irregular CT with containing bundles of collagen and some elastic fibers
Contains many structures including hair follicles, glands, blood vessels, nerves |
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The Hypodermis
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Also called subcutaneous layer
Contains adipose tissue, blood vessels, and nerves Serves as a storage of fat, contains large blood vessels that supply the skin |
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Skin Color
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Caused by the accumulation of three pigments in the skin:
Melanin Hemoglobin Carotene |
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Melanin
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A brown pigment produced by melanocytes in the stratum basale of the epidermis
The concentration of melanin that melanocytes produce and transfer to keratinocytes determines skin color |
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Production of Melanin
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Melanocytes synthesize melanin from amino acid tyrosine in the presence of tyrosinase
UV light increases the enzymatic activity, therefore increases melanin production |
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Function of Melanin
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Gives color to skin from yellow to red-brownish to black
Acts as a shield that absorbs UV radiation and protects keratinocytes from the damaging effects of the sun |
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Albinism
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Inherited inability to produce melanin because of absence of tyrosinase
Missing melanin in hair, eyes, skin |
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Vitiligo
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An autoimmune destruction of melanocytes
The partial or complete loss of melanocytes Irregular white spots |
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Hemoglobin
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A red pigment found in the red blood cells
The reddish skin color is due to the skin’s vascularity Seen best in thin-skinned individuals |
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Carotene
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A yellow-orange pigment used to make Vitamin A
Stored in the stratum corneum, dermis, and hypodermis Gives carrot their orange color |
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Abnormal Skin Coloration
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May indicate medical diseases:
Cyanosis Jaundice Erythema Pallor |
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Cyanosis
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Low oxygen concentration in the blood causes a bluish discoloration
May indicates: Cardiovascular disease Poor blood circulation Hemoglobin abnormalities |
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Jaundice
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Breaking down hemoglobin produces a yellow pigment, Bilirubin
A yellowish appearance to the skin and the whites of the eyes Causes: Liver and gallbladder disease Hemolysis of RBCs Neonatal conditions |
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Erythema
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Indicates increased blood flow to the skin
Causes: Inflammatory conditions Infections Allergic reactions |
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Pallor
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Indicates reduced blood flow to the skin or reduced RBCs
Causes: Blood loss Anemia Shock May be normal |
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Tattooing
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Injecting ink with a needle into the dermis
Can be removed by lasers Laser light causes tattoo to dissolve into small ink particles That are removed by immune system cells |
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Accessory Structures of the Skin
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Hair
Nails Sweat Glands Sebaceous (oil) glands Arrector Pilli muscle |
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Hair
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Composed of tightly packed layers of keratin
Present on all areas of the skin except: Palmar surfaces of hands and fingers Plantar surfaces of feet and toes Lips |
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Anatomy of a Hair
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Two parts:
Shaft: above the surface of the skin Root: penetrates into the dermis, sometimes even the subcutaneous region |
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Bulb of a Hair Follicle
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Papilla: loose CT with blood vessels and nerves
Melanocytes: secrets melanin, amount determine hair color Matrix: actively dividing cells; responsible for hair growth If matrix cells stop dividing or are destroyed >> no replacement>>baldness |
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Functions of Hair
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Protection of scalp from UV light
Reduction of heat loss from the head Filters debris from the eyes, nose, and ears Light touch sensation |
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Nails
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Plates of tightly packed keratin layers
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Sagittal Section Through a Nail
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Nail matrix: actively dividing cells, causes nail growth
Nail bed: secures the nail to the finger tip |
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Functions of Nails
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Enable to grasp small objects
Protect the end of the digits Defense (scratch) |
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Sweat Glands
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Four million sweat glands in the skin
Two types: Eccrine Apocrine |
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Eccrine (Merocrine) Sweat Gland
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Most common types of sweat glands
Most numerous in the skin of the palms, soles, and on the forehead Watery secretion with a large concentration of various solutes Stimulated when body temperature rises, also to response to emotional stress Functions: Eliminate wastes Thermoregulation |
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Apocrine Sweat Gland
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Mainly in the armpit, external genitalia, and breasts
Viscous secretion Becomes active in puberty under the influence of testosterone Stimulated by stress and sexual excitement Function(s) ??? |
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Ceruminous Gland
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Modified sweat glands in the external ear
Secrets cerumen or ear wax Functions: Traps debris Dampens sounds Waterproofs the canal |
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Sebaceous Gland
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Connected to hair follicles
Secrets an oily substance called sebum Becomes active at puberty under the influence of testosterone Functions: Coats the hair Adds softness to the skin Antibacterial properties |
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Acne
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Inflammation of sebaceous glands
Blockage of sebum secretion (black head) Sebum may become contaminated with bacteria (white head) |
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Arrector Pili Muscles
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Smooth muscle tissue attached to the connective tissue of the hair follicle
Contraction causes the hair to become erect Responsible for “goose bumps” Used for defense |
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Functions of the Skin
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Thermoregulation
Protection Waterproofing Sensation Excretion and absorption Synthesis of Vitamin D |
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Thermoregulation
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By liberating eccrine sweat glands secretion and adjusting the flow of blood in the dermis
Response to hyperthermia: Secretion of eccrine sweat glands causes evaporative cooling of the skin Vasodilation of blood vessels allows heat to be redistributed to the skin surface Response to hypothermia: Eccrine sweat glands are inhibited Vasoconstriction of blood vessels prevents heat loss through the skin |
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Protection
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Thick, keratinized epidermis acts as a physical barrier that prevents traumatic injury to underlying tissues and entrance of microorganisms
Sebum is antibacterial Melanin absorbs UV radiation |
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Synthesis of Vitamin D
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Keratinocytes use UV light to convert inactive vitamin D to its active form
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Waterproofing
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Stratum corneum acts as a barrier to water loss
Lamellar bodies in keratinocytes release a lipid that acts as a water-repelling sealant |
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Sensations
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Skin contains sensory receptors that can detect:
Pain Touch Stretch Vibration Pressure |
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Excretion and Absorption
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Excretion: elimination of salts, ammonia, urea from eccrine sweat glands
Absorption: directly through the epidermis and into dermal blood vessels Gases, lipid-soluble materials, toxins |
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Disorders of the Skin, Burn
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Tissue damage to the skin caused by :
Excessive heat and/or flames Corrosive chemicals Electricity |
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Determination of the Extend of a Burn
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Rule of nine
Regions of the body are in multiples of 9% |
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Classification Based on Depth of Burn
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First-degree burn: only epidermis
Second-degree burn: epidermis and parts of the dermis Third-degree burn: epidermis and all of the dermis |
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First-Degree Burn
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Only the epidermis is affected
Skin usually appears red Mild pain No blisters Mild sunburn is an example |
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Second-Degree Burn
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Epidermis and parts of the dermis are affected
Redness, edema, pain Blisters usually appear |
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Third-Degree Burn
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Epidermis, all of the dermis, and subcutaneous layer are destroyed
Skin function is lost Are usually painless |
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Forth-Degree Burn
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All layers of skin are burned
Underlying muscle and bone are also burned |
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Complications of a Severe Burn
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Circulatory Shock: due to water loss through burned skin
Infections: loss of protective barrier Electrolyte problems: electrolytes are lost with water Respiratory problems: if face or upper airways are burned Wasting: during recuperation, ingestion of calories keep up with energy needs, weight loss occurs |
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Disorders of the Skin, Skin Cancer
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Transformation of normal skin cells into tumor cells caused by excessive exposure to sunlight
UV radiation >>damages DNA>>mutations occur>>cells transform Classification is based on the cell that transforms |
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ABCD’s of Melanoma Diagnosis
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Many melanomas arise from preexisting moles
Examination of a mole involves: Asymmetry of the mole Borders are irregular Colors are not uniform Diameter of mole > 6 mm; depth (determined by biopsy) |
