lecture 5 Flashcards
generic integumentary system functions (6)
- regular body temp
- protect from external insults
- sense signals
- excrete and absorb chemicals
- store blood and energy
- synthesize vitamin D
generic skin facts (2, weight, thickness)
- 7% of body weight
- thinnest 0.5mm eyelid, thickest 4mm heel
skin layers
epidermis
dermis
subcutaneous (technically not part of skin)
epidermis (make up)
- most superficial skin layer
- has 4-5 layers (thin and thick skin)
- made of many cells like keratinocytes and melanocytes
keratinocytes (SFL)
- layered cells that make keratin
- make lamellar granules (waterproof and sealant)
- located in the epidermis
melanocytes
- contain melanin granules
- absorbs UV light and protects DNA
- found in epidermis
melanin
brown/black pigment that collects of the surface of the nucleus facing UV light
how does UV light damage DNA?
interferes with replication by oxidizing molecules it hits. leads to unstable intermediates due to unpaired electrons
(oxidize = rip electrons)
intraepidermal macrophages (langerhans cells)
- UV sensitive phagocytes
- scour tissue for invaders to destroy
Tactile epithelial cells
- sense touch
- in direct contact with nervous tissue
epidermal strata (5, in order, superficial to deep)
stratum corneum
stratum lucidum (only in thick skin)
stratum granulosum
stratum spinosum
stratum basale
stratum basale (SFL)
- contains stem cells capable of dividing to replenish overlying strata
- rich in keratin intermediate filaments
- provides foundation for skin, reinforces cell junctions
- deepest layer of epidermis
stratum spinosum (SFL)
- 8-10 layers of flat keratinocytes
- cells contain thicker, tougher keratin intermediate filaments
- reinforce desmosomes
- provide strength for the skin
- less capable of division
- superficial to stratum basale
stratum granulosum (SFL)
- 3-5 layers of cells that are dying (apoptosis)
(organelles disintegrate, keratin filaments stay) - produce keratohyalin
- make lamellar granules
- boundary between metabolically active cells and dead cells of epidermis
- superficial to stratum spinosum
keratohyalin
dark staining substance that aids in keratin intermediate filament assembly
lamellar granules
contain lipids that release as cells die
seal underlying layers from invasion and fluid loss
stratum corneum (SFL)
- most superficial layer of skin
- flat thin cells stacked
- cells are dead and slough off with abrasion
- replenished by division from stratum basale
stratum lucidum (SFL)
- only found in thick skin
- superficial to stratum granulosum
- looks clear
- made of dead keratinocytes
- have thick keratin filaments and thick plasma membranes that provide mechanical support to thick skin
growth of epidermis (2)
- takes 4-6 weeks for new cells at basale to emerge at corneum
- keratinization reinforces skin by accumulation of keratin from cells that die by apoptosis
dermis (SFL)
- made of connective tissue
- great tensile strength
- papillary + reticular region
papillary region
- top 20% of the dermis
- made of areolar CT + collagen and elastic fibres
- contains dermal papillae
- contains nervous tissue
dermal papillae
tissue extensions from the dermis into the epidermis that contain capillaries
reticular region
- bottom 80% of the dermis
- made of dense irregular CT
- mesh-like network of collagen + fibroblasts
- resists tearing and shear
- contains glands, nerves, and blood vessels
- anchors dermis to subcutaneous layer
finger prints (SF)
epidermal ridges on the skin
same shape of dermal papillae
increase friction to aid grip
nevus
mole
tyrosinase
contained in melanin to help in melanin synthesis (tanning)
carotene
stored by the stratum corneum
orange in colour and can turn skin orange if there is too much
general hair functions (4)
- protects scalp from UV radiation
- protects eyes and nasal cavity from invasion
- traps air close to skin to minimize heat loss
- contain touch receptors
anatomy of a hair (7)
- hair root - embedded in dermis or subcutaneous layer
- hair shaft - superficial portion of hair
- medulla - deepest layer of hair, contains pigmented cells
- cortex - middle layer, bulk of hair
- cuticle - outermost layer, flat keratinized epithelial cells
- hair follicle - surrounds hair root
- hair matrix - divides lots to grow hair
arrector pili
smooth muscle that moves hairs under certain conditions
- cold
- fear
keeps air close to body to heat up
hair root plexus
dendrites that interact with hair follicle
hair growth stages (3)
growth stage
regression stage
resting stage
growth stage of hair (2)
- hair matrix divide and push new cells up and out of the follicle
- older cells keratinize and die
regression stage of hair (2)
- hair matrix cells atrophy (stop functioning) and die
- shaft growth arrests
resting stage of hair (2)
- period of inactivity in the root matrix
- after resting, old hair root falls out of follicle and is replaced
what affects hair growth? (6)
genetics, nutrition, stress, mechanical damage, age, illness
lanugo
down like hairs that cover fetus
terminal hairs
thicker hairs (head hair, eyebrows, lashes)
vellus hairs
peach fuzz like hairs
vellus and terminal hair distribution in males and females
female - vellus - 65%, terminal 35%
male - vellus - 5%, terminal 95%
eumelanin
type of melanin in made by melanocytes in the hair follicle that makes brown/black hair
pheomelanin
type of melanin made by melanocytes in the hair follicle that makes blonde/red hair
grey and white hair causes (2)
grey - decreased melanin production
white - air bubbles in the shaft of hair
sebaceous glands (SFL)
- empty into hair follicles usually
- lubricates hair and prevents fluid loss
- secretes oil (sebum)
- inhibits microbial growth
- located in the dermis
desiccation
drying out
how does sebum inhibit microbial growth?
sebum is metabolized by bacteria on the skin into fatty acids, resulting in a no optimal pH for invaders to grow
sudoriferous glands (SFL)
(numbers too)
- 4-5 million in the body (dermis)
- secrete sweat on the surface of skin
- aids in thermoregulation (hot sweating)
- minor role in excretion of wastes
sweat components (8)
water, ions, urea, uric acid, ammonia, amino acids, glucose, lactic acid
types of sudoriferous glands
eccrine sweat glands
apocrine sweat glands
eccrine sweat glands (SFL)
- widely distributed in the body
- start in dermis, opens on skin pore
- produce 400-600ml per day
- thermoregulatory sweating
apocrine sweat glands (SFL)
- found in axillae, groin, areolae, under facial hair in males
- sweat contains lipids and proteins that make it a yellow or milky colour
- starts at puberty
- emotional sweating
ceruminous glands (SFL)
- located in subcutaneous layer
- open into ducts of sebaceous glands
- product cerumen (ear wax)
- protects ear canal from invasion
nails (2)
- hard, keratinized epithelial cells packed tightly at the distal end of the digits
- protects the fingertips
nail body
- made of hard, flat keratin
- appears pink due to capillaries
free edge
- same hard tissue as the nail body but appears white
- not vascularized
nail root
- Embedded in the skin
- visible white crescent is called the lunula
hyponychium
thick skin under the free edge
lunula
white crescent at the base of the nail, part of the nail root
eponychium
- comprised of stratum corneum
- skin layer at the base of the nail
nail matrix
contains actively dividing cells that permit growth
- rate of 1mm/week on fingers, slower on toes
- affected by age, health, nutrition, temperature
- longer digit, longer nail
nail functions (4)
- protect the tips of the digits
- support and provide resistance for pressure applied at palmar surface
- aids in touch sensing
- permits grasping and scratching
coordinate functions of integumentary system (8)
- thermoregulation
- changing blood flow in the dermis
- protection
- blood storage
- cutaneous sensation
- minor excretion
- absorption
- vitamin D synthesis
synthesis of vitamin D
enzymes in liver and kidney process precursor activated by UV light into calcitriol
calcitriol
active form of vitamin D processes by liver and kidneys
what does calcitriol d?
- affects calcium absorption - main thing
- stimulates production of antimicrobial substances in immune cells
path of vitamin D synthesis (5)
- inactive precursor
- active precursor (by UV light
- processed by liver / kidneys
- becomes calcitriol
- affects Ca absorption and antimicrobial substances
epidermal wound healing (3)
- superficial cuts break contact of epidermal cells to the basement membrane
- stimulates migration of basal cells
- epidermal growth factor stimulates basal cells to divide and replenish strata
deep wound
a would that penetrates the dermis
four phases to healing
inflammatory phase
migratory phase
proliferative phase
maturation phase
inflammatory phase (3)
- blood clot plugs wound
- injured tissue secretes histamine which dilates blood vessels and permits more blood
- immune cells are recruited to the area
migratory phase (2)
- fibroblasts migrate along clot and secrete collagen and glycoproteins to form granulation tissue
- epithelial cells migrate to fill in wound
granulation tissue
tissue that can start the process of scar formation (fibrosis)
proliferative phase (3)
- epithelial cells divide beneath scab
- fibroblasts secrete collagen to lay down new ECM for new tissue
- blood vessels grow
maturation phase (3)
- epithelium thickens to near normal
- fibroblasts recede
- scab falls off
fibrosis (scar tissue formation) (3)
- have more dense and tough collagen networks
- less flexible
- fewer blood vessels, glands, etc
hypertrophic scars
scars that lie within the bounds of the original wound
keloid scars
scars that extend beyond the original wound margin
edema
can result from third degree burns and lead to dysregulation of body fluids and shock
sepsis
increased risk to bacterial infection
What is cancer?
- uncontrollable cell proliferation
- benign cancers grow fast, malignant even faster
- malignant cancers invade health tissues
basal cell carcinomas effected layer
stratum basale, most common type, generally benign
squamous cell carcinomas effected layer
stratum spinosum
malignant melanomas effected layer
stratum basale
