Skin Flashcards
functions of skin?
- barrier
- prevent dehydration
- largest sensory organ
- thermoregulation
- metabolic functions
- immune functions
- communications.
what are the layers of skin?
epidermis, dermis, subcutaneous layer (hypodermis)
Features of epidermis?
avascualar.
Features of dermis?
blood vessels, nerves, hair follicles, sweat glands.
features of hypodermis?
fatty layer, adipose tissue, energy reserve, thermoregulation.
how thick is skin?
0.5mm –> 5mm
What is the thinnest skin?
eyelid (0.5mm)
what is the most sensitive skin?
lips.
what are the thickest skin?
soles, palms.
how is skin innervated?
- dermamyotome.
- derma cells become the dermis and drag nerve supply with them so cutaneous nerves are segmental.
what is a dermatome?
area of skin innervated by fibres from a single root.
What are angiosomes?
regions of skin, superficial fascia, deep fascia and possibly even underlying muscle that share common blood supply.
What is the histology of epidermis? from most deep to superficial.
- stratum basale.
- stratum spinosum.
- stratum granulosum
- stratum lucidum
- stratus corneum.
features of stratum spinosum?
-spiny looking cells as they have shrunked a little bit and have a border around them still have nuclei, come from stratum basale.
features of stratum granulosum?
- develop granules inside them called keratohyalin granules.
- start laying down of keratin and other proteins that make the skin water resistant.
- have nuclei.
features of stratum lucidum?
- no nuclei, almost dead, fill up with protein (mostly keratin)
- only found in thick skin.
features of stratum corneum?
-dead, forms protective layer mainly consisting of keratin.
how do the cells in the deepest level of the epidermis function?
extremely active and divide constantly to make more and more new cells.
What happens to the new cells made in the deepest level of the epidermis?
they are pushed upward through the other levels of the epidermis and toward the surface of the skin.
What is the blood supply for epidermis?
no direct blood supply, all nutrient that feed these cells come from the dermis
What are cell types in epidermis?
- keratinocytes
- malanocytes
- langerhan cells
- merkel cells
what is the primary function of keratinocytes.
-responsible for forming tight junctions with the nerves of the skin.
what does the epidermis primarily consist of?
keratinocytes.
what is a secondary fucntion of keratinocytes?
keep langerhan cells of the epidermis and lymphocytes of the dermis in place.
what do melanocytes do?
make melanin.
what do melanocytes appear as?
appear as small cells, usually in or near stratum basale.
what do langerhan cells do?
participate in the surveillance of immune system.
what do langerhan cells look like?
smaller than keratinocytes, with clear cytoplasm, usually located within the stratum spinosum or stratum basale.
what do merkel cells do?
- small cells associated with nerve endings in epidermis.
- involved in tactile sensation.
what is the dermis?
thick layer of connective tissue to which the epidermis is attached.
what are the 2 sublayers of the dermis?
- papillary layer
- reticular layer with thicker elastin fibres and bundles of collagen
what does papillary layer adhere to?
epidermis.
what does reticular layer adhere to?
subcutaneous tissue.
what are tension lines determined by?
alignment of dermal connective tissue and effect of underlying muscle
why does skin bounce back?
elastin.
Where are sebaceous glands derived from?
epidermis.
where are sebaceous glands located?
dermis.
what is the shape of seb glands?
flask-shaped and packed solidly with cells that often have a foamy appearance ins sections.
where are seb glands found?
found everywhere in the body.
what do seb glands do?
produce a substance called sebum which keeps cells and skin moisturised.
structure of seb glands?
a duct from each gland opens into an associated hair follicle.
where is sebum found?
most of the body except palms and soles.
what do eccrine sweat glands secrete?
produce mostly NaCl and water.
where are apocrine glands found?
mostly in axilla and groins.
what do apocrine glands secrete?
milky secretion directly into hair follicles.
what is the size of apocrine sweat glands compared to eccrine sweat glands?
apocrine are much larger.
what do ceruminous glands secrete?
ear wax.
what do mammary glands secrete?
milk.
what muscle is arrector pili muscle?
smooth muscle.
what is innervation of arrector pili muscle?
sympathetic. part of flight or fight.
what is hyperhidrosis?
excessive sweating in hands and feet.
where are hair follicels located?
dermis.
metabolic function of skin?
vitamin d3 is made in the skin. important for bone health/calcium metabolism.ski
5 skin sensations?
fine, vibration, light touch, temp, pain
where are langerhan cells found?
epidermis.
where are mast cells found?
underneath epidermis, under blood vessels.
where are macrophages found?
dermis.
where are melanocytes found?
basal layer of the epidermis.
how many melanocytes do different people have?
same number.
