skin physiology Flashcards
what are the skin layers from superficial to deep
epidermis, appendages (nails, hair, glands, mucosae), DEJ, dermis (connective tissue), sub cutis (fat)
where is thick skin found
palms and soles
what are blaschko’s lines
growth pattern of skin in embryology
when does the epidermis form in embryology
16 weeks
what is vit D and thyroxine metabolised by
keratinocytes
in thyroid metabolism, what % of T4 is converted to T3 and what is the real names
80%. (thyroxine) –> (triiodothyronine)
what receptors in the skin detect temperature
thermoreceptors
what sense cells are associated with pressure and vibration,
pacinian and meisseners
what are the 6 functions of the skin
barrier, metabolism, thermoregulation, immune defence, communication, sensory function
what type of epithelium is the epidermis
stratified squamous
what are the 4 cells in the epidermis
melanocytes, keratinocytes (95%), langerhans and merkel cells
what are the 4 layers of the epidermis
keratin (horny/ stratum), granular, prickle cell, basal
what do keratinocytes differentiate into, what is their main function
corneocytes - no nuclei, tight water proof barrier
where do keratinocytes migrate from
basement membrane
what do keratinocytes produce
keratin
what cells are in the granular layer and what is there a high content of
Odland cells, no nuclei, high lipid content
what cells are in the prickle cell layer and what are there lots of
Polyhedral, desmosomes and langerhans
what cells are in the basal layer, where do they cells proliferate from
cuboidal, proliferate from basal layer to keratin layer
what epidermal layer is metabolically active
basal layer
what are melanocytes and where do they migrate from
pigment producing dendritic cells, migrate from neural crest
how to melanocytes produce pigment
convert tyrosine –> melanin pigment
what colour are eumelanin and phaemomelanin
brown/ black and red/ yellow
what is the function of melanin, melanin caps and melanosomes
melanin absorbs light, melanin caps protect nucleus, melanosomes (pigment) are transferred to keratinocytes
where do langerhan cells come from and where are they found
bone marrow, mainly prickle cell layer in epidermis
what are langerhan cells and what granule do they have
main immunological cells - birbeck granules
where are merkel cells, what are they
basal level, mechanoreceptors for sense
what is the worst type of skin cancer
merkel
what is the pathophysiology of vitiligo
autoimmune loss of melanocytes
what is the pathophysiology of albinism
genetic partial loss of pigment (melanin)
what is the pathophysiology of nelsons disease
pit gland produces excess melanin stimulating hormone
what are hair follicles
specialised keratins and dermal papilla (pigment from melanocytes) next to sebaceous glands
what are the phases of hair growth
anagen = growing, catagen = involuting, telogen = resting
what are nails made of
specialised keratins
what are the 3 types of skin glands and where are they found
sebacous - around hair follicles, apocrine - dermis, eccrine - dermis
what is the function of sebaceous glands and what activates them
produce sebum (oil) in holocrine secretion to pilary canal and protect from fungus. hormone sensitive
what is the function of apocrine glands and what activates them
produces oily fluid that smells bad (sweat), androgen dependent
what is the function of eccrine glands and what activates them
sympathetic cholingeric nerve supply, cools by evaporation and grips hands and feet
how permeable is the DEJ
semi-permeable
what cells are in the dermis
fibroblasts, macrophages, mast cells, lymphocytes,
what fibres are in the dermis
collagen (type 1 and 111), elastin
what is unique about the blood supply to the skin
blood supply greater than the need for evaporation
what role to lymphocytes have in skin immunology
immune surveillance
