Lesson 7
Reticular layer
- Deeper, thicker layer of dermis - Composed of dense irregular connective tissue - Stretch marks (striae) - tears in the collagen fibers caused by stretching of the skin due to pregnancy or obesity - Damaged dermal blood (burns, shoe friction) may cause serious fluid to seep out and form a blister dermis and epidermis
myoepithelial cells
- Found in both apocrine and eccrine glands - Contract in response to stimulation by sympathetic nervous system and squeeze perspiration up the duct
Melanoma
Arises from melanocytes Less than 5% of skin cancers Can be successfully removed if caught early, but usually fatal if metastasizes Greatest risk factor is familial history Highest incidence in men, redheads, people who had severe sunburn as a child
Mammary glands
___________ _________- milk-producing glands that develop in female during pregnancy and lactation --- Mammary ridges or milk lines - two rows of mammary glands in most mammals
Epidermal ridges
are downward waves of epidermis
Dermal papillae
are upward, finger-like extensions of dermis
Decubitus ulcer
bedsores caused by problems with dermal circulation
bulb
in dermis or hypodermis, hair root ends with dilated _____
Dermatitis
inflammation of the papillary layer
ceruminous glands
modified sweat glands, located in external ear canal, produce cerumen (earwax)
layers of epidermis
stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum
integumentary system
The _____________ ___________ consists of the cutaneous membrane (skin) & accessory structures (hair, nails, glands)
squamous cell carcinoma
- Arises from keratinocytes of stratum spinosum - Lesions usually on scalp, ears, lower lip, or back of the hand - Have raised, reddened, scaly appearance later forming a concave ulcer - Chance of recovery good with early detection and surgical removal - Tends to metastasize to lymph nodes and may become lethal
Skin colors of diagnostic value
- Cyanosis: blueness due to oxygen deficiency - Erythema: redness due to increased blood flow to skin - Pallor: Paleness due to decreased blood flow to skin - Albinism: white skin due to genetic lack of melanin - Vitiligo: Loss of skin color in patches due to loss of melanocytes, probably cause by autoimmune reaction of melanocytes - Jaundice: yellowing due to bilirubin in blood - Hematoma: bruising, blood clotting under skin
Hypodermis
___________ (subcutaneous tissue) - layer of connective tissue beneath the skin
Subcutaneous fat
___________ _________ - refers to subcutaneous tissue that is comprised predominantly of adipose tissue
Skin markings
- Friction ridges: formed from dermal papillae - Flexion lines (flexion creases) - Freckle: flat, melanized patch - Mole (nevus): elevated, melanized patch, often with hair ---- Should be watched for changes in color, diameter, or contour that may suggest cancer - Hemangiomas (birthmarks) ---- Patches of discolored skin caused by benign tumors of dermal capillaries ---- Some disappear in childhood, others last for life ---- Examples: capillary hermangioma (strawberry birthmark), cavernous hemangioma, port-wine stain
Papillary layer
- Thin zone of areolar tissue in and near the dermal papillae - Allows for mobility of leukocytes and other defense cells - Rich in small blood vessels
skin grafts, autograft & allograft
- Third-degree burns often requires ________ - _______ - tissue from another location on the same person's body - _______ - tissue from unrelated person, usually deceased donors
Five epidermal cell types
1. Keratinocytes 2. Stem cells - In deepest layer of epidermis, stratum basale 3. Melanocytes -synthesize pigment melanin that shields DNA from ultraviolet radiation - occur only in stratum basal but have branched processes that spread among keratinocytes and distribute melanin via melanosomes 4. Tactile Cells - Tactile disc - collective term for tactile cell and associated nerve fiber 5. Dendritic cells - Found in stratum spinous and stratum granulosum
pilus & hair follicle
A hair is also called a _____ (plural: pili) - Slender filament of keratinized cells growing from a tube in the skin called a _____ ______
dermis
Beneath the epidermis is the ________
dermal papilla, hair matrix
Bulb grows around _____ ______ - bud of vascular connective tissue, provides nutrition to hair ________ _______ - mitotically active cells immediately above the papilla; growth center for the hair
epidermis
General features of the _________ - Keratinized stratified squamous epithelium - Avascular (lacks blood vessels) - Contains sparse nerve endings for touch and pain
Soft keratin & hard keratin
Hair and nails are composed of mostly dead, keratinized cells - Pliable ______ ______ makes up stratum corner of skin - Compact ____ _____ makes up hair and nails
Medulla, cortex, & cuticle
Hair has up to 3 layer: ______ - Core of loosely arranged cells and air spaces ______ - bulk of the hair; layers of elongated cells ______ - outermost region consisting of multiple layers of thin, scaly cells that overlap like roof shingles
accessory organs
Hair, nails, and cutaneous glands are the _________ ________ (appendages) of the skin
Carotene
Lack of vitamin A can cause night blindness (nyctalopia)
lamellar granules, exfoliates, dander, epidermal water barrier
Life History of a Keratinocyte Keratinocytes produced by mitosis in stratum basal or deepest part of stratum spinosum - Over time, keratinocytes flatten, produce more keratin and lipid-filled ______ ______ - In 30 to 40 days a keratinocytes makes its way to the skin surface and ________ (flakes off) as specks called _______ (may combine with oil to become dandruff) --Calluses or corns are thick accumulations of dead keratinocytes on hands or feet ____________ _______ _________ - located in the stratum granulosum, it is formed from lipids from keratinocytes as well as tight junctions between them
basal cell carcinoma
Most common type Least dangerous because it seldom metastasizes Forms from cells in stratum basale small, shiny bump with central depression and beaded edges
nerve fibers
Sensory _____ ______ entwine each follicle and respond to hair movements
skin
The _____ (integument) is body's largest and heaviest organ
eumelanin, pheomelanin
Skin Color Dark _______ and reddish-yellow _______ - Eumelanin varieties: brown and black eumelanin; responsible for tan, brown, and black skin - Possible accumulation of carotene pigment from yellow and orange vegetables (carrots, squash)
Epidermis, Dermis, Hypodermis
Skin Consists of two layers: _________: Stratified squamous epithelium _________: dipper connective tissue layer-accessory structures originate in the dermis Below the dermis is the ________ (superficial fascia/subcutaneous layer), not part of the skin but usually studied with it.
eccrine sweat glands
Sweat glands - Mose numerous skin glads - 3 to 4 million in adult skin, especially dense on palms, soles, and forehead - simple tubular glands produce watery perspiration that help cool the body
Apocrine sweat glands
Sweat glands -Groin, anal region, axilla, areola, beard area in men - Ducts lead to nearby hair follicles; produce sweat that is milky and contains fatty acids - Inactive until puberty; respond to stress and sexual stimulation -- Bromhidrosis - disagreeable body odor; usually inadequate hygiene
Downy hair, vellum hair, & terminal hair
Three types of hair: ______ _______ (lanugo) --- Fine, downy, unpigmented hair that appears on the fetus in the last 3 months of development _____ _______ --- Fine, pale hair that replaces lanugo by time of birth --- Two-thirds of the hair of women; 1/10 of the hair of men; all the hair of children except eyebrows, eyelashes, and scalp hair _____ _____ --- Longer, coarser, more heavily pigmented --- Eyebrows, eyelashes, and hair of the scalp --- After puberty, forms axillary and pubic hair --- Male facial hair and some of the hair on the trunk and limbs
Basal cell carcinoma, squamous cell carcinoma & malignant melanoma
Three types of skin cancer names for the epidermal cells in which they originate: _________ _______ ________ _________ _______ ________ ___________ ______________
Thin skin
_____ _____ covers rest of the body
Sebaceous glans
_____ _____ produce oily secretion called sebum
Epithelial root sheath
_____ ______ _______ extension of the epidermis lying adjacent to hair root; widens at deep end into bulge, a source of stem cells for follicle growth
Guard hairs
______ ______ (vibrissae) guard nostrils and ear canals
Thick skin
______ ______ covers the palms, soles, and corresponding surfaces of fingers and toes
Shaft & root
______ is portion above skin surface, _____ is portion below skin surface
arrector muscle
_______ _______- bundle of smooth muscle attaching follicle to dermis; contracts to make hair stand on end (piloerection)
insensible perspiration
________ ________ - not noticed; does not produce visible wetness of skin. lose approx. 500 ml/day ---- Cutaneous transpiration - water loss from skin not due to sweating. Water diffuses between keratinocytes and evaporates from the skin surface
Burns, first degree burn, second degree burn & third degree burn
________ can result in death due to fluid loss, infection, and toxic effects of eschar - the burned, dead tissue classified according to depth of tissue involvement: _____ ______ ______ - only involves the epidermis -redness, slight edema, and pain - heals within days _____ ______ _______ (partial-thickness burn) - involves part of dermis - may appear red, tan , or white; blistered and painful - two weeks to several months to heal and may leave scars _____ _____ _______ (full-thickness burn) - involves all of dermis and often some deeper tissues - often requires skin grafts; need fluid replacement, infection control, supplemental nutrition
diaphoresis
________- sensible perspiration, sweating with wetness of the skin, in response to the heat, exercise, circulatory shock
Connective tissue root sheath
_________ ________ ________ ________ - derived from dermis but a bit denser; surrounds epithelial root sheath
Functions of the skin
protection, vitamin D synthesis, sensation, thermoregulation, nonverbal communication
Dermatology
scientific study and medical treatment of the integumentary system