LESSON 5: INTEGUMENTARY SYSTEM Flashcards
largest organ of the body that forms a physical barrier between the external environment and the internal environment that it serves to protect and maintain.
integumentary system
components of integumentary system
skin
nails
hair
cutaneous sense organs and glands
2 major tissue layers of the skin
epidermis and dermis
- superficial layer
- stratified squamous epithelium
- cornified or keratinized (hardened by keratin) to prevent water loss
- avascular
- most cells are keratinocytes
epidermis
prevents water loss and resists abrasion
epidermis
- dense connective tissue
- vascular
- 10-20 times thicker than the epidermis
- layer of dense connective tissue depending on location
(blood vessels, oil and sweat glands, nerves, hair follicles, and other structures)
dermis
- responsible for most of the skin’s structural strength
- skin rests on the subcutaneous tissue, which is a layer of connective tissue
(ex. areolar, adipose) - not part of the skin, but it connects skin to underlying muscle or bone
dermis
- functions as padding and insulation
- acceptable percentage of body fat varies from 21% to 30% for females and 13-25% for males
dermis
- cells are dead
- represented only by flat membranous sacs filled with keratin
- glycolipids in extracellular space
stratum corneum
- cells are flattened
- organelles are deteriorating
- cytoplasm full of granules
stratum granulosum
- cells contain thick bundles of intermediate filaments made of pre-keratin
stratum spinosum
- cells are actively dividing stem cells
- some newly formed cells become part of the more superficial layers
stratum basale
dermis consists of
sensory nerve ending
melanin granules
melanocytes
excessive sloughing of stratum corneum cells from the surface of the scalp is called
dandruff
in skin subjected to friction, the number of layers in the stratum corneum greatly increases, producing a thickened area called
callus
keratinization is also called
cornification
keratinocytes proliferate in the
basal layer (mitosis)
a complex process that results in the production of the impermeable stratum corneum
terminal differentiation (keratinization)
LAYERS OF THE EPIDERMIS
thick hairless layer
- stratum corneum
- stratum lucidum
- stratum granulosum
- stratum spinosum
- stratum basale
dermis
- deepest layer of epidermis
- lies next to dermis
- wavy borderline with the dermis anchors the two together
stratum basale (stratum germinativum)
- cells undergoing mitosis
- daughter cells are pushed upward to become the more superficial layers
stratum basale (stratum germinativum)
- several layers thick
- contain a weblike system of intermediate filaments
stratum spinosum (pricky layer)
- 4-6 layers thick
- accumulates two types of granules: KERATOHYALINE GRANULES and LAMELLAR GRANULES
stratum granulosum (granular layer)
help to form keratin in the upper layer
keratohyaline granules
contain water-resistant glycolipid for slowing water loss across the epidermis
lamellar granules
- formed from dead cells of the deeper strata
- occurs only in thick, hairless skin of the palms of the hands and soles of the feet
stratum lucidum (clear layer)
- outermost layer of the epidermis
- shingle-like dead cells are filled with keratin (protective protein prevents water loss from the skin)
stratum corneum (horny layer)
over a bony prominence, the stratum corneum can thicken to form a cone-shaped structure called a
corn
Why is it that soles and palms have no hair?
- Grip and traction
- sensitivity
- hygiene
- heat regulation
- palms of hands, soles of feet
- 5 epidermal layers (including stratum lucidum)
- protective, withstands friction and wear
- no hair follicles or sebaceous (oil) glands
thick skin
- rest of the body
- 4 epidermal layers, w/o stratum lucidum
- sensory perception, touch, and temperature sensitivity
- contains hair follicles, sebaceous glands, and sweat glands
thin skin
cells in the epidermis
- keratinocytes
- melanocytes
- dendritic (Langerhans) cells or intraepidermal cells
- tactile (Merkel) cells
- produce keratin, a fibrous protein that helps give the epidermis its protective properties
- arise in the deepest part of the epidermis, stratum basale
keratinocytes
- spider-shaped epithelial cells
- synthesize melanin pigment
- found in the deepest part of the epidermis
melanocytes
arise from bone marrow and migrate to the epidermis
- ingest foreign substances
- key activators of our immune system
dendritic (Langerhans) cells or intraepidermal cells
- present at the epidermal-dermal junction
- functions as sensory receptor for touch
tactile (Merkel) cells
layers of the dermis
epidermis
papillary layer of dermis
reticular layer of dermis
2 layers of dermis
papillary dermis (upper dermal region)
reticular dermis
- areolar connective tissue
- collagen and elastic fibers form a loosely woven mat
- projections called dermal papillae
— some contain capillary loops
— others house pain receptors and touch receptors called tactile or Meissner’s corpuscles
papillary layer (upper dermal region)
- 80% of the thickness of the dermis
- dense fibrous connective tissue
- cleavage (tension lines): important to surgeon
- flexure lines: dermal folds that occur at or near joints
reticular layer
topological lines drawnon a map of the human body
Langer’s lines, Langer lines of skin tension, or sometimes called cleavage lines
result ofa complex interaction between internal and external factors involving the skin
skin tension lines
places where the dermis has folds to accommodate joint movement
flexure lines
incision made across cleavage lines
- can gap
- increase time needed for healing and result in increased scar tissue formation
incision made parallel to cleavage lines
- less gapping
- faster healing, less scar tissue
flexure line types
normal palm creases
simian crease
normal skin color determinants
melanin
carotene
hemoglobin
- polymer made of tyrosine amino acids
- __________: yellow to red
- __________: brown to black
melanin
pheomelanin
eumelanin
- precursor of vitamin A needed for vision
- lipid-soluble
- orange to yellow pigment from some vegetables
- accumulates in the stratum corneum and in fatty tissue of hypodermis
carotene
_________ is produced by melanocytes and packaged into vesicles called ___________
melanin
melanosomes
differences in skin color are due mainly to the amount of pigment the melanocytes produce and transfer to keratinocytes
- red coloring from blood cells in dermal capillaries
- Oxygen content determines the extent of red coloring
hemoglobin
A decrease in _________, as occurs in shock, can make the skin appear pale.
blood flow
A decrease in the _________ produces a bluish color of the skin, called _______.
blood O2 content
cyanosis
produced by the golgi apparatus of the melanocyte
melanosomes
intracellular organelles that are uniquely generated by pigment cells in the skin and eye
melanosomes
Interstitial cell-stimulating hormone, estrogens,melanocyte-stimulating hormoneand adrenocorticotrophin appear to increase epidermal melanin byenhancing the activity of _________
tyrosinase
skins appear bluish
cyanotic
due to embarrassment, inflammation, hypertension, fever, or allergy
redness (erythema)
due to emotional stress such as fear, anemia, low blood pressure, impaired blood flow to an area
pallor (blanching)
liver disorder, gallbladder, or pancreas; occurs when too much bilirubin builds up in the body
jaundice (yellowing)
Vitiligo (skin condition)
depigmentation
Addison’s disease (skin disease)
– primary adrenal insufficiency
bronzing (hyperpigmentation)
genetic disorder
albinism (partial or complete absence of melanin)
hematomas
bruises
skin appendages
- cutaneous glands
1. all exocrine glands
2. sebaceous (oil) glands
3. sweat (sudoriferous) glands - hair
- hair follicles
- nails
- Produce oil (sebum), accumulated lipids and cell fragments
- Lubricant for skin
- Prevents brittle hair
- Kills bacteria
- The sebum is released by holocrine secretion
- Most have ducts that empty into hair follicles; others open directly onto skin surface
- Glands are activated at puberty
oil (sebaceous) glands
simple, branched acinar glands, with most being connected by a duct to the superficial part of a hair follicle.
sebaceous glands
released by holocrine secretion and lubricates the hair and the surface of the skin, which prevents drying and protects against some bacteria.
- oily white substance rich in lipids
sebum
produced in the cytoplasm of the cell and released by the rupture of the plasma membrane, w/c destroys the cell and results to secretion
holocrine secretions
accumulated sebum blocks a sebaceous gland duct
whitehead
material oxidizes and dries
blackhead
an active inflammation of sebaceous glands accompanied by “pimples” – caused by bacterial infection (Staphylococcus)
acne
overactive sebaceous gland, in infants it is known as “cradle cap”
seborrhea
- Produce sweat
- Widely distributed in skin except nipples and parts of external genitalia
2 Types: ______ & _______
sweat (sudoriferous) glands
eccrine and aprocrine
- Numerous and abundant in the palms, soles of the feet and forehead
- Open via duct to pore on skin surface
Produce sweat (clear) – water & few salts
Eccrine (Merocrine) sweat glands
- Aprox. 2,000 are largely confined to the axillary and anogenital areas
- Ducts empty into hair follicles
- Begin to function at puberty
- Release sweat that also contains fatty acids and proteins (milky/yellowish color)
Apocrine sweat glands
term used to classify exocrine glands and their secretions in the study of histology
Merocrine (or eccrine)
bud their secretions off through the plasma membrane producing extracellular membrane-bound vesicles.
apocrine
COMPOSITION
- Mostly water
- Salts and vitamin C
- Some metabolic waste
- Fatty acids and proteins (apocrine only)
sweat
FUNCTION
- Helps dissipate excess heat
- Excretes waste products
- Acidic nature inhibits bacteria growth
sweat
from associated bacteria
odor
modified apocrine sweat glands
ciliary glands
ceruminous glands
mammary glands
Found in the eyelids
ciliary glands
- Modified apocrine glands found in the lining of the external ear canal
- Secretion mixes with sebum to produce cerumen or ear wax.
ceruminous glands
secretes milk
mammary glands
- Produced by hair follicle
- Consists of hard keratinized epithelial cells
- Melanocytes provide pigment for hair color
- Hair grows in the matrix of the hair bulb in stratum basale
hair or pili
Dermal and epidermal sheath surround hair root
hair follicle
- Smooth muscle cells
- Pulls hairs upright when cold or frightened
- Important role: contractions force sebum out of hair follicles to the skin surface where it acts as skin lubricant.
Arrector pili muscle
stage where hair is formed by mitosis of epithelial cells within the hair bulb or hair follicle; these cells divide and undergo keratinization
growth stage
hair has stopped growing in this phase, but is still in the hair follicle.
transition stage
during this time, hairs are shed from the follicle
resting stage
NO HAIR
palms
soles of feet
red part of lips
types of hair growth
lanugo
vellus hair
terminal (androgenic) hair
- thin, fine hair that grows on most of your body. You might know it as “peach fuzz.”
- usually lighter and shorter than terminal hair.
vellus hair
very thin, soft, usually unpigmented downy hair that is sometimes found on the body of a fetal or new-born human, first hair to be produced by the fetal hair follicles
lanugo
thicker, longer hair you have on your scalp, which healthcare providers call
terminal (androgenic) hair
– excessive hairiness
– may result from an adrenal gland or ovarian tumor
hirsutism
hair thinning and some degree of baldness
alopecia
Most common, male pattern baldness
True or frank baldness
- Scale-like modifications of the epidermis
- Heavily keratinized
- Stratum basale extends beneath the nail bed
- Responsible for growth
- Lack of pigment makes them colorless
nails
