Basic aspects of skin biology 1 Flashcards
Main functions of the skin?
Protection, regulation, sensation, vitD production
Types of protection the skin forms?
Mechanical, UVH
How does the skin provide protection?
skin forms a physical and chemical barrier that prevents hazardous chemicals and pathogenic microorganisms from entering in
Types of regulation that the skin provides?
Thermoregulation, immune organ, fluid balance
Skin thermoregulation?
arrector pilli muscles which put hair on end to regulate body temp, and sweat glands to cool us down
SKin immune organ?
immune cells in epidermis which play a role in immune surveillance. Skin is also first contact for pathogens
Skin fluid balance regulation?
physical chemical barrier–> prevents excess water loss
Skin interaction with environment?
Protective (touch smthn hot–> will pull away) and sensory
Skin layers?
Interfollicular epidermis–> dermis–>subcutaneous adipose tissue
What are the three layers that make up the dermis?
Papillary, upper reticular, and lower reticular
Epidermal appendages?
Hair follicles, sweat glands, and sebaceous glands
WHat is the interfollicular epidermis formed and maintained by?
Keratinocytes
What do keratinocytes do?
Manufacture and store keratin
What is keratin?
intracellular fibrous protein that gives skin (nails and hair) hardness and water-resistant properties
What are keratinocytes held together by?
Desmosomes and adherens junctions
Immune surveillance cells in the epidermis?
CD8+ T cells, dendritic epidermal t cells, langerhans cells
What are merkel cells?
Cells that work with sensory neurons to allow us to feel touch
What are melanocytes?
Specialised pigment producing cell
Where are melanocytes found?
Basal layer, at the bottom of the follicular epidermis
Where do melanocytes originate from?
The neural crest
What happens to melanocytes during development?
They migrate out into the developing epidermis
What happens to melanocytes once development is complete?
They remain in the epidermis
Why are melanocytes said to be quiescent?
They divide infrequently (2* per year)
Main function of melanocytes?
provide melanin pigment to their neighbouring keratinocytes
Melanocyte structure?
They have dendritic processes that stick out in between keratinocytes
How many keratinocytes can one melanocyte be in contact with?
10
What effect does UV have on melanocytes?
Stimulates proliferation and pigment production
What effect does UV have on keratinocytes?
DNA damage
What happens as a result of UV damaging keratinocyte DNA?
p53 protein (TF) is activated
Which gene does p53 induce the expression of?
POMC–> pro-opio melanocortin
