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