Exam2Lec3SkinandAppendages Flashcards
What is integument?
Your skin=epidermis +dermis
epidermis has strat sq epithelium
What covers skin?
Keratinized stratified squamous epithelium
epithelium->BM->loose CT (papillary layer)-> dense CT (reticular layer)
What are 6 fxns of skin?
- Barrier
- Homeostasis
- Immunologic (barrier)
- Sensory->nerve tissue (Pacinian +Meissner’s corpuscles)
- Endocrine
- Excretion-> glandular tissue (sweat + oil)
Is they hypodermis typically considered a layer of skin?
NO, it mostly has adipose tissue
also called superfiscial fascia or subcutanuos CT
What is the epidermis?
Epithelium derived from the ectoderm
consists of 5 layers (thick skin) and 4 layers (thin skin)
What are the 5 layers of the epidermis from outer to inner?
5 layers for thick. 4 for thin
- stratum Corneum
- stratum Lucidum (thick skin only)
- Stratum Granulosum
- Stratum Spinosum
- Stratum Basale (germinativum)
Come, Lets Gulp Some Beer
What can we find in the stratum corneum layer of the epidermis?
Dead, flattened keratinized cells=horny cells
What can we find in the stratum lucidum layer (thick skin only) of the epidermis?
Thin+ clear layer of dead, flattened keratinocytes
Acidophilic -> stains more pink/red
What can we find in the stratum granulosum layer of the epidermis?
- H20 barrier
- Keratohyalin granules (not mem bound) + membrane coating granules
- Lamellar bodies-> lipid insoluble proteins=waterproof
basophilic -> stains more purple
What can we find in the stratum spinosum layer of the epidermis?
- Polygonal cells w/desmosomes generates cohesion
- Presence of mitotically active cells
they have spiny projections that form IC bridges which are now known as desmosomes
What can we find in the stratum basale (germinativum) layer of the epidermis?
- single layer of cuboidal or Columnar cells w/desmosomes + hemidesmosomes
- Most mitotically active layer-> replenish cell population
cuboidal or columanr cells rest on basal lamina
What is the layer of cell mitosis?
S. Germinativum/Basale
What is the malphigian layer?
S. Spinosum + Basale, its the most mitotically active region
region of keratinocyte proliferattion
1st degree burns
can the epidermis be repaired?
what layer of skin is damages and/or unharmed?
- Patient can repair epidermis
- Damage to S. Corneum +Lucidum +Granulosum +Spinosum
- The S. Basale is unharmed & can restore the lost cell population
2nd degree burns
can the epidermis be repaired?
what layer of skin is damages and/or unharmed?
- The pt can regenerate lost epidermis from dermis
- Damage to all layers of the epidermis
- Sweat glands + hair follicles in the dermis (derived from S. Basale of the epidermis) can regenerate epiderm
3rd degree burns
can the epidermis be repaired?
what layer of skin is damages and/or unharmed?
- The pt has complete loss of the epidermis + dermis
- Can only repair w/ skin grafts
- Most dangerous burn b/c loss of H20 barrier can cause death
What type of cells can we find in the epidermis?
Keratinocytes, langerhans cells, melanocytes, merkel cells
What is the most abundant cells type?
keratinocytes
Explain keratinocytes
where is it produced?
where it prolif?
where they accumulate and die?
where it moves?
what does it store?
- Produced in S. basale-> move to Spinosum + proliferate
- As cells mature they accumulate keratin filaments (granules)
- Start to die in the S. granulosum-> move to Corneum
- Can store melanin produced by melanocytes
As keratinocytes mature and differentiate, what do they produce?
Keratin hyaline granules and lamellar bodies
What goes through a very specialized differentiation to give rise to the protective dead cell layer, the stratum corneum
keratinocytes
Explain Langerhans cells
found in?
derived from?
act as?
- Found in S. Spinosum
- Derived from mesoderm
- Act as immune cell (APC)= migrate into the dermis-> then lymph
NOT attached to adjacent keratinocytes by desmosomes, similar to dendritic cells seen in lymphoid tissues
What are langerhans cells responsible for?
responsoble for engulfing invading microorganisms in the epidermis and presenting antigens to lymphoid cells
Langerhans cells cannot be distinguised easily in H and E, what techniqe must be used to visualize it?
Gold impregnation techniques
Explain Melanocytes
found in?
derived from?
contain?
- Found in S. basale (germinativum) w/ hemidesmosomes
- derived from neural crest cells which allows for migration
- contains tyrosinase-> produces melanin-> gives skin color
melanin protects the keratinocytes from UV radiation
melanocytes are NOT conected to surrounding keratinocytes by desmosomes, but can be attatched to B. lamina by hemidesm
Melanating granules are injected into keratinocytes by a process called ____ secretion
cytocrine
Where do we find the most melanin?
Over nucleus in parts where mitotically active
above nuclei of keratinocytes in the S. Germinativum and spinosum
If you have darker skin, what does this mean in terms of melanin?
Melanin is stored longer in keratin, it is not degraded by keratinocytes as fast
Merkel cells
found in?
what type of cells are they?
- Found in stratum basale (germinativum) of only thick skin
- Specialized keratinocytes=mechanoreceptor (sensory) cells
they cant be distinguisged from keratonocytes in HE stain
What is basal cell carcinoma?
- Occurs only in thin skin (where seb glands are located)
- Affects keratinocytes in the S. basale-> exceeds basal cells in areas they shouldnt be (like the dermis)
What is squamous cell carcinoma?
- Loss of normal (squamous) epithelium-> appearance of cuboidal or columnar cells
- affects keratinocytes all throughout the epithelial layers
What is malignant melanoma?
- Most dangerous form of skin cancer
- Affects melanocytes in the S. basale-> migrate into dermis-> invade blood + lymph vessels to spread cancer
2% of skin cancers
b/c of neural crest origin, they are metastatic
Dermis is made of what 2 layers?
Upper loose CT (papillary layer) + Lower dense CT (reticular layer) underlying the epithelium
not a huge layern of immune cells bc stuff had to get through epidermis
Upper loose CT layer=papillary layer
cellular layer or fibrous layer?
Cell populations?
considered a part of what?
- cellular layer b/c loose CT= more cells than fibers
- Cell populations: fibroblasts, mast cells, macrophages, etc
- considered a part of the dermal papillae or pegs
Lower dense CT=reticular layer
cellular or fibrous layer?
Made up of what type of fiber?
Contents?
- Fibrous layer b/c dense CT has more fibers than cells
- Made up of type 1 collagen fibers
- Contents: sweat glands, seb glands (thin skin only), nerve fibers (pacinian and messners), arrector muscle (thin skin)
The dermis in thick skin is the ____ as thick skin
same
exception is that thin skin has seb glands and arrector m. ( for hair)
structures in the dermis come from cells in the epidermis
A distinction is made b/w thick and skin skin. What is it dependent on?
The distinction is dependent on the thickness of the EPIDERMIS only, nothing to do with dermis
What type of skin is found in areas exposed to greater wear and abrasion?
Thick (glabrous) skin
ex: palms of hands and soles of feet, no hair, so seb glands
What are the appendages of the skin?
- Hair follicales
- sweat glands
- seb glands
- mammary glands
- nails
Where do we find hair follicles?
thick skin only
thin skin only
both
thin
Where do the hair follicles grow from and what is it usually near?
Downgroth (invagination) of epidermis into dermis. Usually near seb (oil) glands in the dermis
also apocrine sweat glands in the armpits
The external and internal root sheaths of the hair follicle have what type of cells and what are they surrounded by?
basal cells and its surrounded by dense CT w/in the dermis
What is dermal papillae? lxn? contains?
- Hair bulb surrounded by root sheath
- located at the bottom of the hair follicle (root)
- contians vasculature to nourish the hair
the cells of the hair bulb are like those of the S, germantivum
The hair itself has 2 layers, what are they?
Cortex + medulla
what is the most common sweat gland?
Eccrine sweat gland
Eccrine sweat gland
what type of secretion?
dervied from what type of cells?
characterized by what type of epithelium?
- watery, non-viscous secretion
- derived from epidermal cells (basal cells) invading down into dermis
- characterized by simple cuboidal epthelium
simple coiled tubular glands
myoepithelial cells help to squeeze out secretions from the glans these cells stain dark pink + contains actin
What are myoepithelial cells?
specilaized cells that help to squeeze out secretions from the glands (sweat acini) these cells stain dark pink + contains actin
they are epithelial, not smooth muscle cells
they are acidophilic b/c they contain actin filaments
What is the less common sweat gland and why?
Apocrine sweat gland b/c it is only located in the axillary, areolar, & anal regions
sexual fxn= phremones-> starts puberty
Apocrine sweat glands
what type of secretion?
glands secrete fluids where?
- protein rich, viscous odorless secretion
- glands secrete fluid into ducts-> ducts open into the hair follicle + secrete fluid
active glands have lots of glandular tissue; inactive is mostly CT w/ scarce amount of glands
the secretions attains a distinctive ordor by the action of bacteria that reside on the skin
What is an example of a modified apocrine sweat gland?
mammary glands
Sebaceous (oil) glands
lxn?
secrete what via what type of secretion?
characterized by what type of cell?
examples?
- located only in thin skin b/c they develop with hair follicles
- secrete sebum (oil) via holocrine secretion-> more active after puberty
- characterized by basal cells (from epidermis)
- ex: lips, glans, clitoris
as cells swell + fill w/ oil, the large cell will lose its nuclei
What type of glands becomes more active at puberty; i.e. respond to hormones and when clogged, they are an ideal site for bacterial growth?
Seb glands
What are nails?
Plates of keratinized epithelial cells (nails are dead skin cells)
What are the nail layers from superficial to deep and note what is in it and/or what it does
- Nail plate: keratanized epithelial cels
- Nail bed: epithelial cells of the S. Spinsom + Basale (malphigian layer)
- Nail matrix:
generates the cells of the nail bed
The nail bed does not contribute to the nail plate
Where does the nail plate grow from?
It grows from the root of the nail and then it grows distally on top of the nail bed
What are free nerve endings?
Unmyelinated axons (nerve tissue) in the dermis penetrate up into the malphgian layer of epidermis.
Temp and pain perception. and crude touch, only type of receptor found in cornea
What is meissner’s corpuscle?
present where?
fxn?
Present in thick skin (most abundant) + thick skin-> identify in upper (papillary) layer of dermis
fxn= discriminative touch /edge detection
What are pacinian corpuscles?
present where?
fxn?
present in thick skin + thin skin -> identify in lower (reticular) layer of dermis and hypodermis
fxn= deep pressure + vibration
responds to tuning fork placedd against skin
Where are Pacinian corpuscles most abundant?
skin of fingertips
