Basic aspects of skin biology 2 Flashcards
(20 cards)
What happens to POMC post translationally?
Cleaved into beta endorphins and alpha melanocyte stimulating hormone (MSH)
What does alpha MSH do?
Binds to receptors on melanocytes that causes a signalling cascade
Result of alpha MSH-induced signalling cascade?
MITF TF activates transcription of pigment synthesising genes
Where in melanocytes does pigment synthesis occur?
Melanosomes
What happens to melanosomes?
Transported to the dendritic tip of the melanocyte via microtubules
What happens to melanosomes once they reach the dendritic tip?
Taken up by the keratinocytes
What do keratinocytes do with the melanosomes?
Arrange them into an umbrella like structure–> shields the nucleus from incoming UV radiation
What is the epidermis maintained by?
Stem cells
Which tissue in the body has one of the highest turnover rates?
Interfollicular epidermis
How often does the human epidermis renew?
Every 4 weeks
Where in the epidermis are the stem cells found?
In the basal layer, anchored to the basement membrane
What are the results from division of epidermal stem cells?
New stem cells and transit amplifying cells (TACs)
What happens to TACs?
Few rounds of differentiation b4 terminal differentiation
What happens to TACs following terminal differentiation?
Detach from basement membrane and become actively stored in the suprabasal differentiation compartment
What happens to cells as the move up the epidermis?
They are terminally differentiating
What do the outermost keratinocytes do?
Provide a protective cover for the skin and protect extensive water loss
State of the outermost keratinocytes?
Dead
Why is the epidermis called a stem cell zoo?
There are several distinct populations found there
Different stem cell groups in the epidermis?
Hair follicle junctional zone, HF isthmus, HF bulge, interfollicular epidermal
