Chapter 5: Integumentary System Flashcards
What does the integumentary system consist of?
skin, hair, nails, sudoriferous glands, sebaceous glands
Skin
cover entire body surface; varies in thickness (1.5-4.0mm) thick; 2 distinct layers
What are the distinct layers of the skin?
epidermis and dermis
Epidermis
keratinized stratified squamous epithelium; avascular; has free nerve endings
What are the cells types found in the epidermis?
keratinocytes, melanocytes, Dendritic (langerhans) cells; tactile epithelial (merkel) cells
Keratinocytes
most abundant type; produce hard keratin (hard protective protein); interconnected via tight junctions and desmosomes (which allow skin to be pliable)
Melanocytes
found in deepest epidermal layer (stratum basale); produce melanin (pigment transferred to keratinoctyes); melanin protects nucleus of keratinocytes from UV dammage (like an umbrella)
What does sun exposure do?
stimulates melanocytes to increase production of melanin which leads to darkening of the skin
Excessive Sun Exposure damages the skin….
leathery skin (clumping of elastic fibers); increase chance of skin cancer; depresses immune system
Dendritic Cells
aka Langerhans cells; defense cells; ingest foreign substances; activate immune responses
Tactile Epithelial Cells
aka Merkel cells; only tactile cells found in epidermis; located at epidermal/dermal junction; detect light pressure
Thick Skin
all layers are thicker and includes the stratum lucidum; no oil glands; made of 5 layers; includes the palms, fingertips, soles of feet; has a thicker stratum corneum; does not have hairs
Thin Skin
made of 4 layers; has oil glands; does not have stratum lucidum; found all over body except for palms, fingertips, soles of feet; has a thinner stratum corneum
Stratum Basale
deepest; single row of mitoti stem cells (produce new keratinocytes); will also find melanocytes and tactile epithelial cells
Stratum Spinosum
aka prickly area (becomes when you do a slide it separates the cells and you can see the desmosomes); several rows of keratinocytes connected via desmosomes; dendritic cells concentrated here
Stratum Granulosum
aka granular layer; 1-5 rows of flattened keratinocytes connected via tight junctions; organelles deteriorating (too far away from nutrients); cytoplasm full of granules
Stratum Lucidum
aka clear layer; ONLY found in thick skin; always on top of granulosum layers; few rows of flat dead keratinocytes
Stratum Corneum
aka horny layer (meaning thick or tough); 20-30 rows of flattened keratin packed cells; intercellular glycolipids provide waterproofing (between cells); sloughed off regulary; not the thickest layer in thin skin
Dermis
vascular, innervated; 2 layers: papillary dermis and reticular dermis; areolar tissue is normally below epidermis
Papillary Dermis
thin, uppermost dermal layer, about 20% of dermis; made of areolar tissue; projects into epidermis forming dermal papillae
Fingerprints
in growing fetus, dermal papillaw of thick skin cretae a unique pattern of epidermal ridges called friction ridges (aka fingerprints); fingerprints of identical twins are different (but they are more similar than siblings)
Reticular Dermis
thick, deep, dermal layer; about 80% of dermis; made of dense irregular connective tissue; collagen fibers form bundles that run paralell to the skin surface; spaces between collagen bundles form cleavage lines
What are stretch marks?
tears in the dermis; form striae
What are blisters?
fluid filled pocket formed at epidermis/dermis junction
What three pigments determine skin color?
melanin, carotene, hemoglobin
Carotene
orange, accumulates in stratum corneum and subcutaneous fat
Hemoglobin
RBC’s in dermal blood vessels; veins appear blue because the hemoglobin is poorly oxidized; blue tinted skin is cyanosis
Hair
covers body except for palms, soles, lips, nipples, and parts of external genitalia; 2 regions- shaft (projects above skin) and root (embedded in skin)
What are the two hair types?
vellus hairs- short and fine (like peach fuzz); terminal hairs- are coarse and thick
Hair Itself
consists of dead keratinized cells arragned in 3 concentric rings; cuticle, cortex, medulla
Cuticle
1 layer of hevily keratinized overlapping cells
Cortex
many layers of pigments cells (melanin, pheomelanin)
Medulla
core; cells contain air spaces; absent in fine/vellus hairs
Hair Matrix
cells that produce hair
Melanocytes
produce melanin and pheomelanin
Hair Papilla
dermal papilla that produces in hair bulb; contains knot of capillaries
Arrector Pili
follicle associated with an arrector pili muscle (smooth muscle); contractions force sebum out of hair follicle onto skin surface; causes hair to stand on end producing goose bumps
Nails
contain hard keratin; produced by nail matrix
Lunule
white proximal half-moon area; not the white part that you cut
Eponychium
cuticle
Sudoriferous Glands
sweat glands; two types eccrine and apocrine
Eccrine Glands
most of sweat glands; secretes primarily water, salts, traces of metabolic wastes and dermacidin (antibacterial) which keeps certain bacteria from living on skin and the acids help with bacteria
Apocrine Glands
begin functioning at puberty; has proteins and lipids but when the bacteria breaks down it starts to smell; NOT involved with temp control
What are modified apocrine glands?
ceruminous glands-produce cerumen (earwax); mammary glands- secrete milk
Sebaceous Glands
produce sebum; oil; lubricates skin and hair; help prevent water loss; everywhere except palms and feet
Functions of the Skin
protection, thermoregulation; sensation, production of vitamin D; blood resevoir; excretion
Protection
chemical barrier- acidic secretions, melanin, dermacidin and sebum; physical barrier-keratinized cells and glycolipids of epidermis; biological barrier- dendritic cells (epidermis) and macrophages (dermis)
Thermoregulation
sweating and shivering
Tactile Corpuscles
located in dermal papillae hairless skin; detect light touch
Lamellar Corpuscle
located in dermis and hypodermis; detect deep pressure
Hair Follicle Receptors
surround hair follicle bulb; detect hair deflection
Free Nerve Endings
epidermis and dermis; detect heat, cold, and pain
Production of Vitamin D
sunlight stimulates skin cells to produce vitamin D
Blood Resevoir
blood vessels in dermis hold 5% of blood volumEx
Excretion
small amounts of nitrogenous wastes (urea, uric acid, ammonia) in sweat
Skin Cancer
most common type of cancer; 3 forms- basal cell carcinoma, squamous cell carcenoma, melanoma
Basal Cell Carcinoma
most common *80%); least malignant; grows slowly; arises from stratum basale cells
Squamous Cell Carcenoma
most often on head and hands; arises from stratum spinosum cells; grows rapidly and will metastasize; curable if caught early
Melanoma
rarest type (1%); but most deadly because highly metastic; arises from melanocytes
ABCD Rule of Melanoma
asymmetry- 2 sides of pigmented area dont match; border irregularity- borders indented; color- areas have several colors; diameter- spot is greater than 6 mm in diameter
1st Degree Burns
epidermis damage; localized redness
2nd Degree Burns
epidermis and upper dermis damaged; redness and blisters
3rd Degree Burns
full thickness; epidermis and entire dermis damaged; requires skin grafting
Burns are critical if…
> 25% of body has 2nd degree burns; >10% of body has 3rd degree burns
Immediate Threat of Burns
loss of body fluids
Subsequent Threat of Burns
infection and sepsis (leading cause of death) which is widespread bacterial infection
