Chapter 5: Integumentary System Flashcards
stratum corneum
1st superficial; 20-30 layers of dead cells filled w keratin; glycolipids for waterproofing; stratified cells called cornified/horny cells
stratum lucidum
2nd superficial; only thick skin; tonofilaments formed by keratohyalin granules sticking to keratin filaments
stratum granulosum
3rd superficial; keratinization occurs; lamellar granules produce glycolipids; keratohyalin involved in keratin formation in more superficial layers
keratinization
keratinocytes become dominated by keratin and their organelles decompose, the cell membrane gets thicker, a form of apoptosis
stratum spinosum
4th superficial; keratinocytes shrunk but held on by deosmosomes giving the “prickly” appearance; cells contain thick bundles of intermediate filaments called pre-keratin
stratum basale
5th superficial; deepest layer; site of rapid mitotic division producing new keratinocytes; melanocytes present; and some dendritic cells
keratinocytes
epidermis-produce keratin
melanocytes
epidermis-produce melanin, form melanosome granules that move and associate to the superficial side of keratinocytes
dendritic cells
epidermis-also “langerhans cells” derived from bone marrow playing a part in the immune system
tactile (merkel) cells
epidermis-at the epidermal-dermal junction, sensory receptors for touch
epidermis
outer protective covering of the skin; avascular
dermis
tough leathery layer full of fibrous connective tissue, fibroblasts, macrophages, mast cells, white blood cells, hair follicles, oil/sweat glands
fibroblast
produces collagen and other fibers
macrophages
large phagocytotic cell
mast cells
release histamine, play a part in immune response and attracting other WBC
cleavage (tension) lines
formed by less dense regions in the pockets of adipose, collagen fiber networks in the ECF of the cutaneous plexus; externally invisible - run longitudinally in the skin of the head and limbs, run circularly around the neck and the trunk
cutaneous plexus
nourishes the reticular layer of the dermis, ECF has pockets of adipose tissue, and bundles of interlacing collagen
clinical importance of cleavage lines
important for surgeons because when they make an incision parallel to these lines, the skin doesn’t gape as much and heals faster
flexure lines
externally visible, e.g. creases of the palms; created at or near joints where the dermis is more securely attached to the deeper structures below
papillary layer
dermis-thin layer made up of interlacing collagen and other fibers heavily invested w small blood vessels creating a loosely woven mat allowing phagocytes and defensive cells to patrol for bacteria
dermal papillae
indent the epidermis, can contain capillary loops, pain receptors, tactile receptors, or tactile (Meissner’s) corpuscles
friction ridges
formed by the epidermal and dermal ridges created by dermal papillae in thick skin; enhance grip ability and sense of touch e.g. fingertips
reticular layer
80% of thickness, coarse irregular arrangement of dense connective tissue, collagen fibers provide strength and resiliency, collagen also binds water for moisture, elastic fibers allow for stretch-recoil
melanin
tyrosine polymer produced my tyrosinase of melanocytes - distributed to keratinocytes of the stratum basale
why do people have different skin colors?
we all have relatively the same # of melanocytes but differences in skin color arise from the different amount and types of melanin produced
tanning
visible darkening of skin - exposure to UV radiation causes faster DNA repair of photodamaged cells, triggers greater production of melanin
carotene
yellow-orangey pigment - concentrated in thicker stratum corneum (palms and soles) and adipose tissue of the hypodermis
hemoglobin
binds oxygen in blood - turns red
pigment indicators of disease states
C-cyanosis E-erythema P-pallor or blanching J-jaundice B-bronzing B-bruising
cyanosis
bluing: lack of oxygen to hemoglobin - heart failure, severe respiratory disorders
erythema
redness - embarrassment, hypertension, inflammation, allergy, fever
pallor or blanching
turning pale - anger, emotional stress, anemia, low blood pressure
jaundice
yellow- liver disease, bilirubin (yellow bile pigment) accumulates in the blood and distributed to tissues
bronzing
metallic - adrenal cortex not producing enough steroid, pituitary gland tumours producing too much MSH
MSH
melanocyte stimulating hormone
bruising
black and blue - blood left circulation forming a hematoma
hematoma
mass of blood clotted underneath the skin
cadherins
calcium dependent adherins: cell adhesion molecules that are important in formation of adherens junctions
epithelial bud
needs to form in order to form a skin appendage via lowered production of cadherins
red hair
colored by iron containing component trichosiderin
main regions of hair
- shaft
2. root
concentric regions of hair shaft
- cuticle
- cortex
- medulla
medulla
innermost region; large cells with air spaces, containing soft keratin; absent in vellus hair
vellus hair
fine hair
terminal hair
thick, dark, coarse hair
cortex
several flattened cells covering the medulla
cuticle
outermost region; heavily keratinized overlapping arrangement of shingle-like dead cells – separates each hair shaft to avoid matting
hair follicle
- peripheral connective tissue derived from the dermis
- glassy membrane (thickened basal lamina)
- epithelial root sheath (inner and outer)
- hair root (cuticle, cortex, medulla)
- hair matrix
- hair papilla
hair matrix
actively dividing
hair papilla
contains capillary knot protruding into hair bulb, nourishes the hair matrix, signals for growth
root hair plexus
hair follicle receptor surrounding the hair bulb - makes hairs sensory receptors for touch
arrector pili
contractions force the hair upright going out of the skin, dimples the skin as goosebumps, functionally important to force sebum out of the hair
hirsutism
excessive hairiness resulting from adrenal gland or ovarian tumour secreting too much androgens
male pattern baldness
delayed-action gene changes response to DHT such that hair follicle lifespan is incredibly short
DHT
dihydrotestosterone
yellow-tinged nails
thyroid or respiratory disorder
thick yellow nails
fungal infection
Beau’s Lines
horizontal lines on the nails; malnutrition
outward concavity of the nails
iron deficiency
sudoriferous glands
sweat glands
myoepithelial cells
associated with sweat glands, specialized cells that contract when stimulated by the nervous system, push sweat through the duct to the skin surface
merocrine glands
secrete by exocytosis
horocrine glands
build up secretion until they become so enlarged they burst
eccrine glands
merocrine sweat gland; palms, soles, forehead; temperature regulation, duct opens at the skin surface
sweat
99% water, vitamin C, antibodies, dermicidin, salts, traces of metabolic wastes
dermicidin
microbe killing peptide found in sweat
apocrine glands
merocrine glands; armpits, anogenital, duct opens into the dermis, lies deeper than eccrine, secretes something similar to sweat with addition of proteins and fatty substances
mammary glands
specialized apocrine; secrete milk
ceruminous glands
specialized apocrine; lining of external ear canal, mix with sebum to produce cerum
cerum
ear wax
sebaceous glands
simple alveolar glands all over the body except palms and soles
sebum
lubricates hair and skin, prevents water loss; bactericidal properties
defensins
natural antibiotics secreted by skin cells
cathelicidins
protective peptide secreted by wounded skin
oleoresins
plant poisons like poison ivy or poison oak that can enter the skin
