Ch6 Integumentary System Flashcards
What is the integumentary systems comprised of?
Skin + accessory organs (hair, nails, cutaneous glands)
What is our most vulnerable organ?
Skin
Skin receives more ________________________________ than any other organ system
Skin receives more medical treatment than any other organ system
Define dermatology
scientific study & medical treatment of integumentary system
What are the functions of the integumentary system?
- Barrier to infection, trauma, water loss
- Vitamin D synthesis
- Sensation
- our most extensive sense organ
- Thermoregulation
- vasoconstriction/vasodilation
- Nonverbal communication
What are the layers of the skin?
- Epidermis: stratified squamous epithelium
- Dermis: connective tissue layer
- Hypodermis (aka subcutaneous layer): below dermis, mostly adipose
What is the difference between thin and thick skin?
- Thin skin covers most of body -hair follicles, sebaceous glands, & sweat glands
- Thick skin—on: palms & soles, fingers & toes -sweat glands, but no hair follicles or sebaceous (oil) glands
Describe the epidermis
- Keratinized stratified squamous epithelium
- dead cells (surface) packed w/ protein keratin
- lacks blood vessels, depends on diffusion
What are the cells of the epidermis and their function?
- Stem cells - mitosis
- Keratinocytes – synthesize keratin
- Melanocytes – synthesize melanin, shields DNA from UV radiation (distribute melanin through branched processes)
- Dendritic (Langerhans) cells - immune
- Tactile cells - sensation
Identify the cells of the epidermis
What are the 5 layers of the epidermis?
- Stratum Basale – deepest; stem cells division
- Stratum Spinosum – multilayered -keratinoctyes flattening; dendritic cells roam
- Stratum Granulosum – 3-5 layers -keratinocytes produce vesicles, release glycolipids (exocytosis) to waterproof skin - barrier cuts off nutrients to distal cells
- Stratum Lucidum (thick skin only)
- Stratum Corneum – can be 30 layers -dead scaly keratinized cells flake off (exfoliate)
Identify the layers of the epidermis
Describe the dermis
- Connective tissue layer deep to epidermis
- Blood vessels, sweat glands, sebaceous glands, & nerve endings
The dermis is anchored to the epidermis by…
Dermal papillae
What 2 zones is the dermis divided into?
- Papillary layer—superficial areolar tissue -allows mobility of leukocytes & other defense cells, if epidermis torn -rich in small blood vessels
- Reticular layer—deeper & thicker layer, dense irregular connective tissue - stretch marks (striae)
Describe hypodermis
- subcutaneous tissue
- mostly areolar & adipose
- pads body
- binds skin to underlying tissues
Drugs introduced by injection in the hypodermis are used because the hypodermis is…
highly vascular, absorbs them quickly
Describe subcutaneous fat
- energy reservoir
- thermal insulation
Describe melanin
Determines skin color—significant factor; brownish black produced by melanocytes; stimulated by UV radiation
Hemoglobin is associated with the color…
red
Carotene is associated with the color…
Yellow
What is albinism?
Lack of melanin
What is cyanosis?
blueness from deficiency of oxygen in circulating blood (COPD)
What is erythema?
redness from dilated cutaneous vessels (anger, sunburn, embarrassment
What is jaundice?
yellowing from excess of bilirubin in blood (liver disease)
What is bronzing?
golden-brown color of Addison disease (deficiency of glucocorticoid hormone)
What is pallor?
pale color from lack of blood flow (fear)
What is a hematoma?
bruise (visible clot)
What are freckles and moles?
tan/black aggregations of melanocytes
- freckle = flat
- mole (nevus) = elevated
What are hemangioma?
- birthmarks—patches of discolored skin; benign tumors of dermal blood capillaries
- strawberry birthmarks disappear in childhood
- port wine birthmarks last for life
What are flexion creases?
form after birth by repeated closing of hand (wrist, hand, elbow)
What are flexion lines?
Lines that form in wrist and elbow areas
Describe hair
- Mostly dead, keratinized cells
- compact hard keratin makes up hair & nails
- (pliable soft keratin makes up stratum corneum)
- slender filament of keratinized cells; grows from oblique tube in skin called hair follicles
- only on thin skin
What is pilus?
another name for hair (pili=plural)
What are the 3 kinds of hair growth throughout life?
- Lanugo
- Vellus
- Terminal
Describe lanugo hair
fine, downy, unpigmented hair on fetus in last 3 months of development
Describe vellum hair
fine, pale hair that replaces lanugo by birth
Define terminal hair
longer, coarser, & usually more heavily pigmented
- eyebrows, eyelashes, & hair of scalp
- after puberty, axillary & pubic hair
- male facial hair, some hair on trunk & limbs
Hair is divisible into which 3 zones along length?
- Bulb: swelling at base where hair originates - only living hair cells
- Root: remainder of hair in follicle
- Shaft: portion above skin surface
Describe dermal papilla
bud of vascular connective tissue encased by bulb
provides hair w/ nutrition
Describe hair matrix
- region of mitotically active cells immediately above papilla
- hair’s growth center
Identify the structures
What are the 3 layers in cross sections zones of hair forem inside out?
- Medulla- core of loosely arranged cells & air spaces
- Cortex- bulk of hair, dense cells w/ hard keratin
- Cuticle - thin, scaly cells that overlap each other; outer covering
What is a follicle?
diagonal tube that dips deeply into dermis, even hypodermis
What pigments contribute to hair color?
- Eumelanin- contributes to dark hair
- Phenomelanin- contributes to red color
Describe hirsuitsm
excessive or undesirable hairiness in non-hairy areas
Describe pattern baldness
- hair loss occurs from specific regions of scalp rather than thinning uniformly (alopecia)
- genetic & hormonal influences
- baldness allele dominant in males, expressed only in high testosterone levels
- testosterone causes terminal hair in scalp to be replaced by vellus hair
Describe fingernails and toenails
- clear, hard derivatives of stratum corneum
- very thin, dead cells packed w/ hard keratin
Describe the nail plate
Hard part of nail
What are the 3 parts of the nail plate?
- Free edge: overhangs fingertip
- Nail body: visible attached part of nail
- Nail root: extends proximally under overlying skin
What are the other nail parts?
- Nail fold—surrounding skin rising above nail
- Nail groove—separates fold from plate
- Nail bed—skin underlying nail plate
- Eponychium (cuticle)—narrow zone of dead skin
- Nail matrix—growth zone of stratum basale at proximal end of nail - 1 mm growth/week
What are the 5 types of glands?
- Apocrine sweat glands
- Eccrine sweat glands
- Sebaceous glands
- Creuminous glands
- Mammary glands
What are the 2 types of sweat glands?
Apocrine sweat glands and eccrine sweat glands
Describe apocrine sweat glands
- in groin, anal region, axilla, areola, bearded area in men; open to hair follicle
- sweat is thicker, milky, contains fatty acids
What is bromhidrosis?
body odor produced by bacterial action on fatty acids
Describe eccrine (merocrine) sweat glands?
- simple tubular glands; watery perspiration
- 99% water, pH 4-6, “acid mantle”
What is sebum?
- oily secretion produced by sebaceous glands
- flask-shaped glands w/ short ducts opening into hair follicle
Describe a holocrine gland?
- secretion of broken-down cells + product (oil)
- replaced by mitosis at base of gland
Describe ceruminous glands
- only in external ear canal
- secretions + sebum + dead epithelial cells = earwax (cerumen)
- keeps pests outs!
Describe mammary glands
milk-producing glands activated only during pregnancy & lactation
Describe skin cancer
- Induced by UV rays of sun
- most common in fair-skinned & elderly people
- common cancer; among easiest to treat
- high survival rates if detected & treated early
What are skin cancers named after?
Named after the epidermal cells in which it originates
Describe basal cell carcinoma
- most common
- least dangerous, seldom metastasizes
- Forms in: stratum basal
- Lesion is: small bump with central depression, beaded edges
Describe squamous cell carcinoma
- good recovery chance w/ early detection & surgical removal
- tends to metastasize; may become lethal
- Forms in: stratum spinosum
- Lesion is: raised, reddened, scaly appearance later forming concave ulcer
Describe malignant melanoma
- < 5% of skin cancers, but most deadly form
- treated surgically if caught early
- metastasizes rapidly; unresponsive to chemotherapy; usually fatal
- Forms from: melanocytes; often in preexisting mole
Describe burns
- UVA & UVB improperly called “tanning rays” & “burning rays”
- might initiate skin cancer
Sunscreens protect from sunburn but unsure if they protect against…
Sunscreens protect from sunburn but unsure if they protect against CANCER
What are the leading cause of accidentally death?
- Burns due to:fires, kitchen spills, sunlight, ionizing radiation, strong acids or bases, or electrical shock
Burn deaths are primarily from…
- Fluid loss
- infection
- toxic effects of eschar (burned, dead tissue)
What is debridement?
removal of eschar
Describe first-degree burns
- partial-thickness burn; involves only epidermis
- redness, slight edema, & pain
- heals in few days
- most sunburns
Describe second-degree burns
- partial-thickness burn; involves epidermis & part of dermis
- leaves part of dermis intact
- two weeks to several months to heal; may scar
- blistered; very painful
Describe third degree burns
- full-thickness burn; involves epidermis & all of dermis, & often Some deeper tissues (muscles)
- Often requires skin grafts, fluid replacement & infection control
Describe autograph
tissue taken from another location on same person’s body
Describe isograft
skin from identical twin
Describe homograft (allograft)
from unrelated person
Describe heterograpft (xenograft)
from another species
What are other ways for skin grafting?
Artificial skin from silicone and collagen
