Principles of Anatomy Tortora Ch. 5 Integumentary System

skin and accessory structures such as hair, nails and glands, as well as blood vessels, muscles and nerves

organs of the integumentary system

cutaneous membrane

the skin; covers the body and is the largest organ of the body

dermatology

the medical specialty for the diagnosis and treatment of disorders of the integumentary system

epidermis and dermis

Two major layers of the skin

epidermis

outer, thinner layer of the skin; composed of keratinized stratified squamous epithelium

dermis

inner, thicker layer of the skin; composed of connective tissue (dense irregular) containing collagen and elastic fibers

hypodermis

located beneath the dermis; a subcutaneous layer which attaches the skin to the underlying tissues and organs

keratinocytes, melanocytes, langerhans cells, merkel cells

Four major types of cells contained in the epidermis

keratinocytes

90% of the cells in the epidermis; produce keratin that provides protection (from heat, abrasions, microbes and chemicals)

melanocytes

cells of the epidermis that produce the pigment melanin that protects against damage by ultraviolet radiation

langerhans cells

cells of the epidermis involved in immune responses against microbes (intraepidermal macrophage cells)

merkel cells

which function in the sensation of touch along with the adjacent tactile (merkel) discs; also called tactile epithelial cells

four layers

number of layers in the thin skin of the epidermis

five layers

number of layers in the thick skin of the epidermis

thick skin

where exposure to friction is greatest, such as fingertips, palms, and soles

stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, stratum basale (Can Little Girls Speak British?)

layers of the epidermis

stratum corneum

25-30 rows of dead keratinocytes with keratin, continuously shed and replaced with cells from deeper strata

stratum lucidum

3-4 rows of clear, flat, dead keratinocytes with keratin; in thick skin only (fingertips, palms and soles

stratum granulosum

3-5 rows of flattened keratinocytes: organelles begin to degenerate; contain granules (lamellar granules)

stratum spinosum

8-10 rows of polyhedral keratinocytes; melanocytes and Langerhans cells

stratum basale

deppest layer where continuous cell division occurs which produces all other layers; a single row of cuboidal or columnar keratinocytes; stem cells, all other three types of cells are scattered

stratum germinativum

stratum basale

dermis

composed of strong dense irregular connective tissue containing collagen and elastic fibers

papillary region and reticular region

two layers of the dermis

papillary region

outer region of the dermis; consists of areolar connective tissue containing collagen and elastic fibers

dermal papillae

small, fingerlike structures that project into the undersurface of the epidermis; greatly increase the surface contact between the papillary region and the epidermis

corpuscles of touch (meissner's corpuscles)

in dermis, sensitive nerve endings that detect touch

capillary loops

located in dermis, blood capillaries in the dermal papillae

free nerve endings

in dermis, in the dermal papillae, dendrites that lack any apparent structural specialization

reticular region

bottom region of the dermis, attached to the subcutaneous layer; consists of dense irregular connective tissue containing collagen and elastic fibers (which provide strength, extensibility, and elasticty to the skin), adipose cells, hair follicles, nerves

epidermal ridges

sit over the dermal papillae; reflect contours of the underlying dermal papillae and form the basis for fingerprints (and footprints); their function is to increase firmness of grip by increasing friction

melanin, carotene and hemoglobin

variations in skin color arise from variations in the amounts of these three pigments

melanin

located mostly in the epidermis where it absorbs UV radiation

carotene

pigment found in the stratum corneum dermis and sub-q layer; partly responsible for variations in skin color

hemoglobin

pigment located in erythrocytes flowing through dermal capillaries; partly responsible for variations in skin color

albinism

inheirited inability to produce melanin

vitiligo

condition in which there is partial or complete loss of melanocytes

cyanotic

occurs because hemoglobin is depleted of oxygen; skin appears bluish

jaundice

due to buildup of the yellow pigment bilirubin in the blood

hypodermis (subcutaneous layer)

composed of adipose and areloar connective tissue; it is not part of the skin; attaches the skin to the underlying tissues and organs; contains lamellated corpuscles which detect external pressure applied to the skin

hair (pili)

composed of dead, keratinized epidermal cells; primary functions are protection, reduction of heat loss, and sensing light and touch

shaft, root, hair follicle

three parts of a hair

hair shaft

part of hair that projects above the surface of the skin

root

part of hair that pentrates into the dermis

hair follicle

part of hair that surround the root; it consists of an epithelial root sheath which in turn is surrounded by a dermal root sheath

hair bulb

structure of the hair that has an indentation called the papilla of the hair where blood vessels provide nourishment to the gorwing hair

arrector pili

muscle associated with hair (goosbumps)

sebaceous (oil) glands

typically connected to hair follicles; secrete and oily substance called sebum which prevents dehydration of hair and skin and inhibits growth of certain bacteria

sebum

oily substance secreted by sebaceous glands

sudoriferous (sweat) glands

produces sweat

eccrine and apocrine

two types of sweat glands

eccrine sweat glands

type of gland that has an excretory duct that opens at a pore at the surface of the epidermis; the sweat secreted by these glands helps to cool the body by evaporating, and also eliminates small amounts of wastes

apocrine sweat glands

type of gland located mainly in the skin of the axilla, groin, and bearded facial regions of adult males; their excretory ducts open into hair follicles

ceruminous glands

modified sweat glands located in the ear canal; along with nearby sebaceous glands, they are responsible for producing a waxy secretion called cerumen which provides a sticky barrier that prevents entry of foreign bodies into the ear canal

cerumen

ear wax; a waxy secretion provides a sticky barrier that prevents entry of foreign bodies into the ear canal

nails

composed of hard keratinized epidermal cells located over the dorsal surfaces of the ends of fingers and toes

free edge, nail body and nail matrix

three main parts of the nail

free edge (of nail)

top/tip of the nail

lunula

whitish part at base of nail

nail body

transparent part of nail below free edge and above lunula

nail root

part of nail embedded in a fold of skin

hyponychium

nail bed; located under the free edge of the nail; attaches the nail to the fingertip

eponychium

cuticle; attaches the margin of the nail wall to the neighboring epidermis

nail matrix

in which cell division occurs resulting in growth of the nail

basal cell carcinoma

least malignant and most common form of skin cancer; startum basale cells proliferate and invade the dermis and hypodermis

squamous cell carcinoma

arise from keratinocytes of stratum spinosum; arise most often on scap, ears and lower lip

melanoma

highly metastic and resistant to chemotherapy; chance of survival is poor if lesion is over 4mm thick

Assymmetry, Border, Color, Diameter

ABCD Rule

burns

tissue damage caused by excessive heat, electricity, radioactivity, or corrosive chemicals that destroy the proteins in the skin cells

first degree burn

burn in epidermis only; mild pain; skin functions remain in tact

second degree burn

destroys a portion of the epidermis and possible parts of the dermis; redness, blister, pain; some functions lost

third degree burn

burn that destroys a portion of the epidermis, the underlying dermis, and the associated structures; most functions lost