Integumentary system 1 Flashcards
what % is skin in total body weight
7%, 10lb
Skin aka
cutaneous membrane
function of integumentary system
- Regulate body temperature
- stores blood
- protects body from external environment
- Detects cutaneous sensations/provides sensory information about the surrounding environment
- Excretes and absorbs substances
- Synthesizes Vit. D
Epidermis
superficial thinner portion layer
contains epithelial tissue
Avascular
Stratified squamous epithelium
Dermis
Deep thicker portion/layer
Contains connective tissue
Vascular
Subcutaneous layer or hypodermis
Not a part of the skin Attaches dermis to underlaying fascia contains areolar and adipose tissue Functions Fat storage an area of blood vessel passage an area of pressure-sensing nerve endings
Deep to subcutaneous layer
Fascia
the connective tissue around muscle and bone
5 (or 4) layer of the Epidermis
Stratum basale (stratum germinativum) Stratum spinosum stratum granulosum stratum lucidum (only in palms ad soles) stratum corneum
Four principle cells of the Epidermis
Keratinocytes - produce the protein keratin. waterproof sealant
Melanocytes - produce the pigment melanin for skin color and absorbs uv light
Langerhans cells - derived from bone marrow, participating in immune response
merkel cells - sensory structure called tactile (Merkel) disc and function in the sensation of touch
slowly senses touch near surface
Merkel (tactile) disc
Rapidly senses touch near surface
Meissner corpuscle
Slowly senses stretching in deep layers of skin
Ruffini corpuscle
Senses movement of the hair
Hair root plexus
Senses pressure
Pacinian corpuscle
Free nerve endings that senses pain rapidly
Nociceptors
What does stratum basale aka stratum germinativum have
- Deepest layer, a single row cuboidal or columnar keratinocytes
- contains merkel cells, melanocytes, keratinocytes and stem cells that divide repeatedly to produce keratinocytes
- Keratinocytes have a cytoskelton of tonofilaments
- cells attached to each other and to basement membrane by desmosomes and hemi-desmosomes
When the germinal portion of the epidermis is destroyed…
new skin can not regenerate with a skin graft
Stratum spinosum is
- providing strength and flexibility to the skin
- 8-10 cell layers are held together by desmosomes
- During slide preparation, cells shrink and appear spiny (where attached to other cells by desmosomes)
- Melanin is taken in by keratinocytes (via phagocytosis) from nearby melanocytes
Stratum Granulosum is
transition between the deeper, metabolically active strata and the dead cells of the more superficial strata
- 3-5 layers of flat dying cells that show nuclear degeneration (example of apoptosis)
- contain lamellar granules that release lipid that repels water
- contain dark-staining keratohyalin granules that convert tonofilaments into keratin
Stratum Lucidum is
only in the finger tips, palms, soles
three to five layers of clear, flat, dead cells
contains precursor of keratin
Stratum corneum is
- 25-30 layers of flat dead cells filled with keratin and surrounded by lipids
- continuously shed
- barrier to light, heat, water, chemicals and bacteria
- lamellar granules in this layer make it water-repellent
- constant exposure to friction will cause this layer to increase in depth with the formation of a callus, an abnormal thickening of the epidermis
Keratinization is
replacement of cell contents with the protein keratin, occurs as cells move to the skin surface over 4-6 weeks
what hormon plays a role in epidermal growth
Epidermal growth factor (EGF)
What is dandruff
an excessive amount of keratinized cells shed from the skin of the scalp
a chronic skin disorder characterized by a more rapid division and movement of keratinocytes through the epidermal strata
Psoriasis
cells shed in 7-1- days as flaky silvery scales
commonly found at knees, elbows and scalp
skin grafts (3)
autograft - self
isograft - twin
autologous graft - patient’s skin grown in culture
Dermis is
connective tissue layer composed of collagen and elastin fibers, fibroblasts, macrophages and fat cells
contains hair follicles, glands, nerves and blood vessels
THICKER than the epidermis, thickness varies, thickest in sole and palms
Two major regions of dermis
papillary region
reticular region
papillary region
top 20 %
thin Areolar collagen tissue and fine elastic fibres for strength and extensibility, adipose cells, hair follicles, sebaceous glands, sudoriferous gland
surface area is increased by finger like projections - dermal papillae
Dermal papillae does (3)
- anchors epidermis to dermis
- contain capillaries that feed epidermis
- contains Meissner’s corpuscles (touch) and free nerve endings for sensations of heat, cold, pain, tickle and itch
The reticular region
bottom 80% of dermis
attached to the subcutaneous layer
Dense irregular connective tissue
contains interlacing collagen and elastic fibres
contains oil glands, sweat gland, ducts, fat and hair follicles, blood vessels, nerves
provides strength, extensibility and elasticity to skin
Epidermal ridges
from as downward projections of the epidermis in fetus (3 month)
Epidermis confirms to dermal papillae
Finger prints are left by sweat glands open on ridges
increase grip of hand
dermal tears from extreme stretching
stretch marks
3 pigments contributing to Skin color
Melanin - pale-yellow to reddish-brown to black
Carotene - yellow-orange pigment that gives egg yolks and carrots their color (located in Dermis, precursor of vitamin A used to synthesize pigments needed for vision)
Hemoglobin: red, oxygen-carrying pigment in blood cells
Where is Melanin produced and what converts to melanin?
produced in epidermis by melanocytes
melanocytes convert TYROSINE to melanin
UV in sunlight increases melanin production
Same number of melanocytes in everyone, but different amount of pigments produced
Where is Carotene found?
in dermis, in stratum corneum and dermis
paleness maybe due to shock or anemia
pallor
yellow color to skin and whites of eyes due to build up of yellow bilirubin in blood from lier disease
jaundice
bluish color to nail beds and skin due to hemoglobin depleted of oxygen
cyanosis
redness of skin due to enlargement of capillaries in dermis
Erythema - inflammation, infection, allergy or burns
Frecles
genetic prediposition
melanin accumulates in patches, reddish brown
age spots
(liver spots)
Flat blemishes, light brown to black (darker than freckles)
accumulations of melanin over time due to sunlight
don’t fade in winter
>40 years of age
Nevus (mole)
Develops in childhood or adolescence
round flat or raised benign over-growth of melanocytes
inherited inability to produce melanin due to melanocytes inability to produce tyrosinase
Albinism
Affects vision and sunburn easily
Complete or partial loss of melanocytes from patches of skin creates white spots
Vitiligo
may be due to an auto-immune response in which antibodies attack melanocytes
Collagen fibers in reticular region orient in one direction
Tension lines (indicate direction of fibers) Surgery along direction of fibers decreases scarring
Pigment injected into dermis
Tatooing
Body piercing may interfere with
resuscitation masks airway management procedures urinary catheters radiographs delivery of baby
