Integumentary System

Epidermis

Consists of keratinized squamous epithelium that rests on basement membrane. Avascular.

Dermis

consists of loose connective tissue and dense irregular connective tissue. vascularized.

Protection

Protects underlying tissue from damage

Mechanical trauma

stretching, abrasion, and pressure

pathogens

disease causing microorganisms. (acid mantle with pH).

skin protection in the environment

protects against UV rays by secreting lipid based chemicals

sensation

sensory receptors detect potentially harmful stimuli

thermoregulation

maintenance of a stable internal body temp through negative feedback loops

excretion

small amounts of metabolic waste products like lactic acid and urea are released in sweat

vitamin D synthesis

required for calcium absorption needed for nerve and muscle function

keratinocytes

provide strength to epidermis, manufacture keratin and is linked by desmosomes

stratum basale

deepest layer closest to blood supply. single layer of cuboidal or columnar shaped cells. produces keratin and precursors to vitamin D. (MITOTiCALLY ACTIVE).

stratum spinosum

thickest layer with spiky-shaped cells. actively produce keratin and vitamin D (metabolically and mitotically active)

stratum granulosum

3-5 rows of cells with prominent cytoplasmic granules in cells.

stratum lucidum

narrow, clear layer of dead keratinocytes ONLY in THICK SKIN.

stratum corneum

several layers of dead flattened keratinocytes. consist of bundles of keratin with thickened plasma membranes.

dendritic (langerhans) cells

found in the stratum spinosum; phagocytes of immune system that protect skin and deeper tissues

tactile (merkel) cells

found in stratum basale; sensory receptors that detect light touch and differentiate shapes and textures

melanocytes

found in stratum basale, produce melanin

thick skin

found on palms of hands, soles of fingers, soles of feet, and plantar surface of toes

thin skin

found on remainder of body. contains no stratum lucidum and has hair follicles, sweat and sebaceous glands,

callus

additional layers of stratum corneum

papillary layer

superficial layer of dermis, made up of loose connective tissue. surface can fold into projections called dermal papillae.

dermal papillae

provide blood supply to epidermis. house tactile (meissner) corpuscles that respond to light touch and distinguish shape and texture.

reticular layer

deep layer of dermis; made up of dense irregular connective tissue. contains blood vessels, sweat glands, hairs, sebaceous glands and lamellated corpuscles that respond to deep pressure 

skin markings

interactions between epidermis and dermis, visible on epidermis. dermal papillae arrange themselves into dermal ridges, making a fingerprint.

melanin 

produced in vesicles called melanosomes, in melanocytes in the stratum basale.increases on exposure to UV rays. decreases synthesis of vitamin D.

freckle

small area of increased melanin

mole (nevus)

area of increased pigmentation, caused by proliferation of melanocytes

albinism

melanocytes fail to manufacture tyrosinase

carotene

yellow-orange pigment, accumulates in stratum corneum

hemoglobin

iron containing protein in red blood cells that gives blood its red color

pallor

decreased blood flow to dermis to remove heat

erythema

increased blood flow to the dermis to remove heat or during injury

bilirubin

breakdown product of red blood cells, builds up in blood and causes jaundice

cyanosis

low amounts of oxygen are in the blood; from breathing difficulties, low red blood cell number, or if hemoglobin is unable to bind to oxygen.

hair

small, filamentous structures that project from all surfaces of skin. consists of squamous keratinized epithelial cells. 

hair shaft

part of hair that projects from the skins surface, columns of dead keratinized epithelial cells. contains inner medulla, middle cortex, and outer cuticle

hair root

portion of hair embedded in dermis.

hair matrix

in the hair, cells at the base of the root undergo mitosis

hair follicle

(pertaining to hair) an infolding of the epidermis known as the epithelial root sheath, surrounded by the dermal root sheath

arrector pili muscles

attaches to dermal root sheath and contracts, causing goosebumps

hair bulb

enlarged area at base of the hair root with a projection called the hair papilla

alopecia

baldness caused by the death of hair follicles

lanugo

non-pigmented hair that covers body in a fetus

terminal hair

thick, coarser and pigmented hair found on scalp and around eyes

vellus hair

thin, nonpigmented hair found on the rest of the body

hair color

determined by amount of melanin produced

nail

hard structure located at the end of digits

nail plate

portion of the nail that sits on top of the epidermal nail bed

nail body

visible portion of the nail plate

nail root

portion of the nail plate under the skin with the nail matrix

proximal nail fold

covers root

eponychium (cuticle)

distal part of proximal nail fold

medial and lateral nail folds

cover the edges of the nail

hyponychium

attachment site of distal end of nail

sweat glands

all glands release their products by exocytosis, called merocrine secretion

eccrine sweat glands

coiled tubular glands in dermis.

apocrine sweat glands

large glands in dermis, found only in axillae, anal area, and areolae. sweat exits onto hair follicle rather through a pore.

ceruminous glands

modified apocrine glands that secrete ear wax.

mammary glands

specialized glands that produce milk

sebaceous glands

branched glands with clusters of secretory cells called acini that surround small ducts. produce sebum, released through holocrine secretion

holocrine secretion

cell ruptures and adds fragments and debris to the sebum

first degree burns

superficial burn, only epidermis is damaged. erythema and minor pain are present

second degree burns

partial thickness, epidermis and part of or all of dermis are damaged. blistering or scarring occur. most painful burn.

third degree burn

full thickness burn. epidermis, dermis, and hypodermis along with deeper tissues are damaged. no pain because of nerve damage, problems with dehydration due to massive fluid loss

rule of nines

divides body into 11 areas each representing 9% of total body surface. 

skin cancer

linked to exposure to UV radiation and other cancer causing agents

basal cell carcinoma

arises from keratinocytes in the stratum basale. forms an ulcerated crater on skin, and doesn’t metastasize

squamous cell carcinoma

Arises from keratinocytes in the stratum spinosum, forms scaly plaques that bleed or ulcerate. more likely to metastasize

malignant melanoma

least common but most dangerous type of skin cancer. identified by the ABCDE method.