Skin & Breast Flashcards
what are the layers of the epidermis?
- stratum basale
- stratum spinosum
- stratum granulosum
- stratum lucidum
- stratum corneum
where are melanocytes found in the skin?
epidermis
- stratum basale
what is the function of melanocytes?
- synthesise melanin
- transfer melanin to surrounding keratinocytes in melanosomes
- absorb UV light
what stimulates melanocytes?
- MSH
- ACTH
where is most of the melanin found?
keratinocytes
what does skin colour depend on?
amount and type of melanin synthesised
what is normally the largest layer of the epidermis?
stratum spinosum
what is found in the stratum spinosum?
- keratinocytes
- langerhans cells
- merkel cells
what is the function of langerhans cells and are they seen readily on H&E?
- antigen recognition
- no
what is the function of merkel cells and are they seen readily on H&E?
- sensory
- no
describe the structure of the stratum granulosum
- flattened squames
what happens in the stratum granulosum?
- keratin formation
- epidermal keratinocytes mature
where is keratin formed?
stratum granulosum
where do epidermal keratinocytes mature?
stratum granulosum
which layer of the epidermis is visible on palms and soles?
stratum lucidum
describe the appearance of the stratum lucidum
thin and pale
what is the stratum corneum?
acellular plates of keratin (as dead keratinised squames)
where is the stratum corneum particularly thick and why?
- palms and soles
- helps to resist abrasive forces
what is the epidermal adnexae?-
downgrowths of the epidermis into underlying layers of the skin (dermis and subcutis)
what is found in the epidermal adnexae?
- hair follicles
- eccrine sweat glands
- apocrine sweat glands
where do hairs arise from?
germinative epithelium within hair bulb
what is responsible for the pigmentation of hair and where are they found?
melanocytes
- germinative epithelium within the hair bulb
where does hair lengthen?
within a root sheath composed of epidermis
what surrounds hair follicles?
collagenous follicle sheath
what muscule causes hairs to ‘stand on end’?
erector pili
where are the erector pili muscles found?
collagenous follicle sheath surrounding hair follicles
are erector pili muscles stimulated sympathetically or parasympathetically?
sympathetically
what is the function of the sebaceous glands associated with hair follicles?
lubricate and waterproof hair
what provides surface lubrication to the face and groin?
hairless follicles
what are apocrine glands?
specialised sweat glands
where are apocrine glands found?
- armpits
- groins
- genitals
- around anus
what produces ear wax?
ceruminous glands in external auditory canal
describe the structure of apocrine glands
- simple coiled tubular glands
- eosinophilic cytoplasm with surface budding
what do eccrine glands secrete?
thin watery secretion associated with sweat
what are the most common sweat glands?
eccrine glands
where are eccrine glands found?
everwhere (in dermis)
what are the 2 layers of eccrine glands:
inner: secretory
outer: myoepithelial
what are rete pegs?
downwards protrusion of the epidermis into the dermis
what is the function of the rete pegs?
help to anchor epidermis onto underlying dermis
what is the papillary dermis?
space between ridges of the rete pegs
what is the dermis?
irregular loose connective tissue layer
what are the 2 elements of the dermis?
papillary dermis
- between rete pegs
reticular dermis
- rest of dermis
what does the dermis contain?
- fibrous connective tissue (with elastin)
- downgrowth of adnexal organs of epidermis
- fibroblasts
- collagen
- glycosaminoglycan matrix
what are the Meissner’s corpuscles?
elongated receptors formed by a connective tissue capsule that comprises several lamellae of Schwann cells
where are meissner’s corpuscles found?
between dermal papillae beneath epidermis of fingers, palms and soles
what is the function of meissner’s corpuscles?
fine touch
what frequency of vibrations are meissner’s corpuscles effecting in transducing?
low frequency
e.g. when textured objects are moved across skin
what are pacinian corpuscles?
large encapsulated sensory receptors
where are pacinian corpuscles found?
- subcutaneous tissues
- interosseous membranes of gut mesentery
(in deep dermis)
what is the function of the onion-like capsule of pacinian corpuscles?
acts as a filter
- only allows high frequencies to activate nerve endings
what is the function of pacinian corpuscles?
discrimination of fine surface textures / other moving stimuli that produce high frequency vibration of the skin
do meissner’s corpuscles or pacinian corpuscles adapt more rapidly?
pacinian corpuscles
do meissner’s corpuscles or pacinian corpuscles have a higher response threshold?
meissner’s corpuscles
what is the function of the subcutis?
- shock absorber
- insulation
- food store
what does the subcutis contain?
- white adipose connective tissue
- fibrovascular septa
what are nails composed of?
compacted keratin
what do nails arise from?
nail matrix cells under cuticle
what are breasts?
myoepithelial system of ducts and lobules set in fibroadipose connective tissue
where do ducts of the breast empty?
nipple
what does male breast tissue contain?
ductal system
what are the functional components of the breasts?
terminal duct lobular units
what is the arrangement in terminal duct lobular units?
secretory lobules arranged around terminal ducts
- et in loose fibrous connective tissue stroma
what are the ducts and lobules in terminal duct lobular units lined by?
outer:
- contractile myoepithelial cells
inner:
- columnar epithelial cells
which cells in breasts adapt to produce milk?
columnar epithelial cells
what is the distinguishing factor of lactating breast?
inner layer of secretory cells become markedly vacuolated
what are the 3 principle histological layers of the skin?
- epidermis
- dermis
- subcutis
what are sweat glands and hair follicles?
downgrowths of epidermis
