Keratinocytes
Produce fibrous protein keratin. Makes structures hard and water resistant.
Melanocytes
Cells in lower epidermia, produce pigment melanin
Langerhans cells
Macrophages that help activate immune system
Merkel cells
Touch receptors
Stratum Basale
Also known as stratum germinativium. Deepest epidermal layer firmly
attached to the dermis. Undergo rapid division.
Stratum Spinosum
prickly layer of the epidermis. Cells contain a weblike system of
intermediate prekeratin filaments attached to desmosomes.
Abundant melanin granules and dendritic cells.
Stratum Granulosom
Granular layer of the epidermis. Thin; 3-5 cell layers in which the
cells flatten.
Keratohyaline and lamellated granules accumulate.
Stratum Lucidum
Clear layer of the epidermis in thick skin. Thin, transparent band
superficial to the stratum granulosum.
A few rows of flat, dead keratinocytes
Stratum Corneum
Horny layer. 20-30 rows of dead, flat, keratinized membranous sacs.
three quarters of the epidermal thickness
Papillary layer
part of the dermis
Areolar connective tissue w/collagen and elastic fibers and blood vessels.
Contains: capillary loops, Meissner's corpuscles, free nerve endings.
Reticular layer
~80% of the thickness of the dermis, collagen fibers provide strength
and resilency. Elastic fibers provide stretch-recoil properties (hair
follicles and glands)
Cleavage lines
located in the reticular dermis.
Collagen fibers arranged in bundles form cleavage (tension) lines.
Incisions made parallel to cleavage lines heal more readily.
Melanin
yellow to reddish-brown to black, responsible for dark skin colors.
Produced in melanocytes; migrates to keratinocytes where it forms
"pigment shields" for nuclei, freckles and pigmented moles.
Carotene
yellow to orange skin pigment.
Most obvious in the palms and soles
Hemoglobon
responsible for the pinkish hue of skin
I.E- when someone turns red from embarrassment or anger
Merocrine sweat gland
also known as Eccrine sweat gland.
abundant on palms, soles, and forehead.
sweat: 99% water, NaCl, vitamin C, antibodies, dermcidin,
metabolic wastes
ducts connect to pores
function in thermoregulation
Apocrine sweat gland
confined to axillary and anogenital areas
ducts connect to hair follicles
functional from puberty onward (as sexual scent glands)
Specialized
-- Ceruminous glands- in external ear canal; secret cerumen
-- mammary gland- secrete milk (from puberty)
Sebaceous Gland
oil gland. Widely distributed. Most develop from hair follicles.
Become active at puberty.
Gland ruptures and produces sebum.
Sebum
oily holocrine secretion, bactericidal, softens hair
and skin, lubricate and water proofs the skin.
Arrector pili
smooth muscle attached to hair follicle.
Responsible for goosebumps.
Alopecia
hair thinning in both sexes after age 40.
Male pattern baldness is caused by follicular response to DHT (dihydrotesterone)
Functions of the Integumetary System
protection body temperature cutaneous
sensation metabolic functions blood reservoir
excretion
3 types of protection barriers of the Integumentary system
Chemical- low pH secretions and defenses against bacterial
activity Physical/mechanical barriers- keratin and
glycolipids block most water and water-soluble substances, plant
oleoresins (i.e. poison ivy), organic solvents, salts of heavy
metals, some drugs Biological- dendritic cells,
macrophages, and DNA Body temp- thermoregulation
Cutaneous sensations- temp, touch (pressure) and pain
Metabolic functions- synthesis of vitamin D and chemical
conversion of carcinogens and hormones. Blood reservoir- up
to 5% of body's blood volume Excretion- nitrogenous wastes
and salts in sweat
Basal cell carcinoma
least malignant, most common.
stratum basale cells proliferate and slowly invade dermis and hypodermis.
Cured by surgical excision in 99% of cases
Squamous cell carcinoma
2nd most common
involves keratinocytes of stratum spinosum (prickly layer)
most common on scalp, ears, lower lip, and hands
Good prognosis if reated by radiation therapy or removed surgically
Melanoma
most dangerous
involves melanocytes. highly metastatic and resistent to chemotherapy
Characteristics of skin cancer
A: Asymmetry; the 2 sides of the pigmented area do not match
B: Border exhibits indentations
C: Color is black, brown, tan, and sometimes red or blue
D: Diameter is larger than 6 mm
First degree burn
epidermal damage only
localized redness, edema (swelling) and pain
Second degree burn
epidermal and upper epidermal damage
blisters appear
Third degree burn
entire thickness of skin damage
no initial edema or pain
Skin grafting is usually necessary
Lanugo coat
covering of delicate hairs in the 5th and 6th month of fetus
Vernix caseosa
subcutaneous gland secretion; protects skin of fetus (end of 6th
month of fetus)