Exam 3: Integumentary System Flashcards
Integumentary system as protective barrier?
mechanical damage toxins dehydration - levels in 3rd degree burns uv light - vitamin D infection
Integumentary system and homeostasis and excretion
homeostasis: fluid, thermoregulation
excretion: glands
integumentary system in immunological and endocrine aspects
immunological: antigen processing
endocrine: growth factors
Integumentary system as vitamin production and sensory
vitamin production: vitamin D
sensory - thermoreceptors, pain receptors
Integumentary Components
skin - cutaneous membrane (epidermis, dermis)
accessory structures - glands, hair, nails
embryo covered by a single layer of ectodermal cells over mesenchymal tissue
embryo - first month
two layers of ectoderm form; deep basal layer will give rise to the epidermis
- the superficial layer forms the periderm
embryo - 2nd month
3 germ cell layers
endoderm, mesoderm, ectoderm
what layer is superficial?
periderm
periderm function
protect you from fluid environment of the amniotic fluid
deep layer
basal
what does the basal layer give rise to?
epidermis
when does the periderm stay until?
keratin can be made by your own cells
multiple layers form, proliferation of basal layer
fetus - 3rd and 4th month
keratinocytes differentiate
keratinization occurs
confined layers appear
periderm breaks down once keratinization is present
5th month plus
keratinocytes
produce keratin
prevent from drying out, irritation
3 key points of the dermis
- dermis development lags behind epidermis by 1-2 weeks
- dermis development influences epidermal development by secreting epidermal growth factor
- proliferation in epidermis causes response in dermis - thickens
feedback between the dermis and epidermis
as epidermis thickens above the dermis, pressure inc in the dermis and the dermis thickens by secreting growth factor
- dermis sends signals for epidermis to get thicker, then causing dermis thickening underneath it
example of epidermis and dermis interactions
calluses on hands
- not system wide, just where the pressure is
the dermis originates from how many sites?
4
3 mesodermal and 1 ectodermal
dermis of back
derived from paraxial somites
dermis of ventral body and appendages
lateral mesoderm
dermis of cranium
superior somites
dermis of face and ventral neck
ectoderm
- same place you get epidermis from
- may see inc in glandular concentration since all ectoderm
somites
segmented regions lateral to the neural tube
- give rise to muscle, nerve, vertebrae, and skin of the region
what is the skin severed by the nerve known as
dermatome
most of the dermis is….
mesoderm
skin development of dermis - 2nd month embryo
dermis begins secretion of growth factors
- locks dermis into epidermis
when does the dermis thicken and differentiate into corium and subcorium
fetus 3-4 months
corium
forms dermal papillae that push into epidermis
sub corium
contains adipose and will separate into the subcutaneous layer
fetus 5th month + dermis
dermis reticular layer develops
- most dense irregular connective tissue that locks into papillae
where can dermatomes be seen (example)
shingles
- lysogenic, dormant in peripheral nerve. when it goes lysogenic you see rash in dermis of dermatome associated with that nerve
- not bilateral
dermatome: skin and nerves innervate skin
5 epidermal layers of skin
basale, spinosum, granulosum, lucisum, corneum
2 dermal layers of skin
dermal papillae
reticular
basale
deepest layer, mitotically active cells, stem cells (keratinocytes), germinativum
spinosum
several layers, cells enlarge, put out projections and attach by desmosomes
dehydration gives cells spiked appearance
granulosum
produces keratohyalin granules
grainy appearance
precursor to hydrophobic fiber
lucidum
subdivision of corneum layer
visible in thick skin
- palm of hand, sole of feet (hard for hair to pass through thick skin)
thin skin - no lucidum layer
corneum
cells are anucleated; keratohyalin is transformed into keratin filaments; deeper layers have extra-cellular lipid barrier for water-proofing
dermal papillae
fingerlike projections that lock the dermis into epidermal ridges (areolar connective tissue)
reticular
thicker portion
dese, irregular connective tissue
bundles oriented along tension lines (langer’s lines)
Langer lines
correspond to mechanical tension on skin
- fiber bundles in dermis line up on these lines
- surgical incisions made parallel to the lines to heal with little scarring
melanocytes
begin migration from neural crest at 2 months
- infiltrate stratum basale at 3 months
- dendritic cells connecting to basale and deeper spinosum keratinocytes
- pigment is produced by tyrosinase and located in melanosomes
langerhans cells
originate in mesenchyme of bone marrow precursors
- infiltrate spinosum
- immunological outposts
- has both mhc I and II
- have receptors for complement and Fc
- can present antigens
merkel’s discs
migrate from neural crest at 4 months
- infiltrates basale and interacts with free nerve endings in dermis
- tactile receptor
accessory structures that infiltrate dermis
hair, glands, nails
what is the development of hair initiated by?
where does localized thickening of epidermis occur?
- signal from dermal fibroblasts
- occurs in placodes
what do underlying dermal mesenchymal cells aggregate?
condensates
the peg epithelial cells envelope the _____ which becomes the _____
dermal condensate
dermal papilla
- cells in contact become matrix - mitotic region
eumelanin
black or brown hair
pheomelanin
blonde, red hair
dermal papilla contains the ___
blood supply
matrix produces cells that differentiate into all hair structures…
medulla
cortex
cuticle
outer root sheath
protective and in contact with basement memrbane
inner root sheath
forms channel
structure of hair
like a pencil
- inner portion medulla
- around medulla = cortex
- outer = cuticle
cuticle
single, overlapping layers of transparent cells
cortex
main bulk of hair - contains pigment and protein fibrils
- determines strength and elasticity
macrofibril
complex of interconnnected fibrils that run length of the shaft
medulla
central hollow core
may be absent or fragmented
