normal skin cell histopathology Flashcards
https://www.ncbi.nlm.nih.gov/books/NBK470464/ https://open.oregonstate.education/aandp/chapter/5-1-layers-of-the-skin/ https://dermnetnz.org/topics/terminology https://www.britannica.com/science/ground-substance https://www.histology.leeds.ac.uk/tissue_types/connective/connective_groundS.php https://dermnetnz.org/topics/terminology
3 layers that make up skin
epidermis
dermis
subcutis / hypodermis
epidermis - main cells found in this layer
keratinocyte
melanocyte
langerhans cell
merkel cell
epidermis - what type of epithelium is it
stratified squamous epithelium
ie columns of flattened cells stack on one another
broadly, the 2 types of epithelium and what’s the difference
epidermis, mucous membrane
- epidermis has a keratin layer that makes it hard and dry
- mucous membranes by comparison don’t have keratin layer and are moist
what are the rete ridges
parts of epidermis that protrudes or invaginates into the dermis
- they look like unitary protrusions, but they’re actually a continuous network hence rete
- they’re what make the small lines on the surface of your skin
what are the dermal papillae
little nipple-like projections from the dermis that fit between the rete ridges. these are solitary hence nipple-y, unlike rete ridges
what is the suprapapillary plate
the section of epithelium that’s between each ridge, it sits on top of a dermal papule
natural progression of keratinocytes
start off deep, moving outwards to the surface
keep accumulating keratin
by the time they’re on the surface they get hard, the nucleus is gone
then eventually its shed off
4((+1) cell layers in epithelium - from deep to superficial
Lucidum is +1
stratum basale
- what layer is it, adjacent layers
- deepest layer of epidermis
- sits superficial to basal lamina, and deep to spinosum
stratum granulosum - characteristics (3)
- sits superficial to stratum spinosum, deep to lucidum/corneum
- cells have basophilic granules
- waxy substance secreted between cells
stratum spinosum - characteristic that gives its name
- desmosomes connect the cells like little prickles
stratum corneum - characteristics
dead, dried out cells without nuclei at the surface of skin
what macroscopic skin structure do the rete ridges correspond with
small lines on the surface of skin correspond with rete ridges
another name for stratum basale
stratum germinativum
another name for stratum germinativum
stratum basale
histology - what does squamous mean
flat, like a roof tile or a lizard scale
name of blood vessels inside the epidermis
none, its avascular
histology - difference between thin skin and thick skin
thick skin has a stratum lucidum
what parts of the body have ‘thick skin’
palms, soles of feet
cell type that makes up 95% of epidermis
keratinocyte
role of keratinocyte in skin
produces and stores keratin
(skin) basal cells
- what does it look like
cuboidal shape
(skin) basal cells
- what cells do these produce
stem cells that produce keratinocytes
what stem cell is the precursor to keratinocytes
basal cell
stratum basale
- how does it connect to the dermis layer
intertwining collagen fibres, known as the basement membrane
stratum basale
- main role
- other cells found in this layer
- its where the basal cells sit and produce keratinocytes
- melanocytes, merkel cells and langerhan cells
merkel cell
- main function
touch sense receptor, sends message to nerves
stratum spinosum
- what gives this layer a spiny appearance
- structures called desmosomes connect the cells in this layer
- its only visible on stained skin cells
stratum granulosum
- what gives the keratinocytes in this layer a granular appearance
keratohyalin accumulation inside the cell
stratum granulosum
- what are the keratinocytes in this layer getting up to
- producing heaps of keratin and keratohyalin
- nucleus and other organelles in the cells die, eventually turning it into a mass of keratin
stratum lucidum
- characteristics (2)
- translucent layer, above granulosum
- dead, flattened keratinocytes
stratum lucidum
- which body parts is it found
thick skin of palms and soles
stratum lucidum
- what gives it a translucent appearance
eleiden, a protein rich in lipids
eleiden
- what is it
- what is it derived from
- role in skin
a protein rich in lipids
derived from keratohyalin
acts as a thick waterproof barrier in stratum lucidum
what layer of epidermis is eleiden found in
stratum lucidum, epidermis
layer of epidermis exposed to environment
stratum corneum
stratum corneum
- characteristics (2)
stack of 15-30 layers of cells, mostly keratin, sitting on the surface of skin
stratum corneum
- how long does this layer take to be replaced
4 weeks
when a bad sunburn happens, why does the skin peel in sheets
stratum corneum cells still have desmosomes connecting to one another, so it comes off as a sheet
ground substance
- brief description
- what’s it made of
- translucent gel component of connective tissue
- made up of large carbohydrates, mucopolysaccharides / glycosaminoglycans
dermis - name of the 2 layers
papillary layer
reticular layer
dermis papillary layer - description
its the layer that forms the dermal papillae, and anchors the epidermis
what skin structures give rise to fingerprints
dermal papillae and rete networks
what skin structures are in dermis (4)
- blood
- lymphatic vessels
- hair follices
- sweat glands
what cell produces connective tissue substances
fibroblast
role of fibroblasts
produce elastin, collagenous fibres, ground substance
characteristics of glycosaminoglycans (3) and their effect
- highly negative charge, which attracts Na+ and therefore water by osmotic pressure
- inflexible, so they resist compressive forces
- hydrophilic ++, keeps them hydrated
4 types of glycosaminoglycans
hyaluronic acid
chondroitin sulphate and dermatan sulphate
heparan sulphate
keratan sulphate
hypodermis - main role
connect skin to underlying fascia (fibrous tissue)
the types of proper ‘non-specialised’ connective tissue and the difference between them
- loose and dense irregular connective tissue
- loose tissue has more actual cells, dense is mostly extracellular matrix
difference in connective tissues of the dermal layers
papillary layer - loose CT
rete layer - dense irregular CT
other names for hypodermis (2)
subcutis, superficial fascia
what makes up the subcutis layer
loose CT and adipose tissue
what layer of epidermis are the melanocytes located
stratum basale
how do keratinocytes get their pigment
melanocytes produce melanin, which gets deposited in keratinocytes as melanosomes
mechanism for skin tanning
excess UV exposure drives up melanin production, which gets deposited in keratinocytes
when UV drops, production drops and skin eventually reverts back to previous color
what role does melanin play in UV exposure
melanin protects DNA from excess UV exposure
what is keratohyalin
protein structure found in granular vesicles inside stratum granulosum, containing keratin, filaggrin
epidermal appendages and their functions
eccrine glands - produce sweat
apocrine glands - scent glands in armpits, groin
pilosebaceous unit - hair and sebaceous gland
nails - to scratch people
what are the eccrine glands
regular sweat producing gland
what are the apocrine glands, where are they located
scent glands in armpits and groin
what are the arrector pili muscles
where are they located in skin layer
muscle attached to hair follicles, controls where the hair points
in the dermis
langerhans cells are part of what body system
immune system
what cells are langerhans cells derived from
there’s debate, some claim monocyte-macrophage, others claim dendritic cells
what immune role do langerhans cells have
antigen presenting cells
characteristic finding of langerhans cells on histopathology
cytoplasmic birbeck granules
what are birbeck granules
cytoplasmic organelles shaped like tennis rackets
what cells are birbeck granules found in
langerhans cells
where do langerhans cells normally reside when inactive
prickle cell layer of epidermis (stratum spinosum)
once activated, where do langerhans cells move to
lymph nodes
