Skin Anatomy & Physiology

1. What are the func- - protection tions of the skin? - thermoregulation (PTSD) - sensory - vitamin D synthesis 2. What are the layers - epidermis of the skin? (3) - dermis - subcutaneous tissue 3. What are the 4 types of cells in the epidermis? - keratinocytes (90%) - melanocytes (8%) - langerhans cells - merkel cells 4. Does the epidermis contains blood vessels? no, it is avascular 5. What do keratinocytes do? produce keratin 6. What do melanocytes do? produces melanin pigment 7. What do Langerhan cells do? provide immunity 8. Where do Langer- bone marrow hans cells come from? 9. What do merkel cells do? Form touch receptors with sensory neurons 10. What is the stratum basale? deepest stratum in epidermis + is a single layer of cuboidal to columnar cells 11. What is stratum - merkel cells basale a combina- - melanocytes tion of? 1/7 - keratinocytes - stem cells that divide repeatedly 12. What is stratum spinosum? 8 to 10 layers of keratinocytes held together by desmosomes 13. What cell in contained in stratum spinosum? langerhan cells 14. What is the stra- 5 layers of flat dying keratinocytes tum granulosum? 15. What does the stratum granulosum show? nuclear degeneration 16. What does the stratum granulosum contain? dark staining keratohyalin granules that bind keratin filaments together 17. What do kerahistidine + cysteine - rich proteins tohyalin granules contain? 18. What do the cells lamellar granules containing lipids + proteins into extrain the stratum cellular space, which creates a lipid envelope around the granulosum secells, forming a hydrophobic-like barrier. crete? Where does it go + what happens? 19. Describe the cells in each of the stratum's of the epidermis: - cells of the S basal get oxygen + nutrient via diffusion from nearby blood vessels in the dermis - cells of the S spinosum have a little bit of mitotic activity - cells of the S granulosum are dying, lose nuclei + organelles - cells in the top layer of S corneum are continuously shed 2/7 20. What is the stratum lucidum? 3 to 5 layers of clear, flat + dead cells 21. Where is the stratum lucidum found? thick skin on the lips, palms + soles of the feet 22. What is the stratum corneum? 25 to 30 layers of flat dead cells filled with keratin + surround by lipids 23. What are the 2 - tough properties of ker- - waterproof atin? 24. What is the stratum corneum a barrier to? - light - heat - water - chemicals - bacteria 25. What stimulates friction callus formation? 26. How are keratinocytes produced? stem cell division 27. What happens when keratinocytes are pushed up towards the surface? they fill with keratin + die 28. What is psoriasis? chronic skin disorder 29. What is the main cells shedding flaky silvery scales (in 7-10 days) symptom of psoriasis? 3/7 30. What causes pso- abnormal keratin production riasis? 31. What stimulates melanin synthesis? exposure to sunlight + hormonal signals which triggers melanocyte stimulating hormone (MSH) 32. Where is POMC protein - a precursor protein melanocyte-stimulating hormone (MSH) derived from? 33. What activates melanin synthesis? MSH binds to melanocortin receptors on melanocytes, increasing production of cAMP 34. When is the pro- during DNA damage tein p53 activated? 35. When is the activation of p53 reduced? when melanin helps to minimise DNA damage 36. How is synthesised melanin packaged? melanosomes package the synthesised melanin into specialised organelles 37. What are the 2 ma- - papillary jor regions of the - reticular dermis? 38. What is the papil- upper 20% of the dermis lary region? 39. What is the pap- loose connective tissue + elastic fibres illary region made of? 40. finger like projections of the epidermis that stick up 4/7 What is dermal papillae? 41. What are the func- - anchors epidermis to dermis tions of the papil- - contains capillaries that feed epidermis lary region? (3) - contains meissnet corpuscles (touch), merkel receptors (touch) + free nerve endings (pain + temp) 42. What is the reticular region of the dermis? dense irregular connective tissue that contains interlacing collagen + elastic fibres 43. What is the retic- - sebaceous glands ular region packed - sweat gland ducts with? - hair follicles with arrector pili muscle 44. What are the functions of the reticular region of the dermis? (2) - provides strength, extensibility + elasticity to skin - contains Pacinian corpuscle receptors (touch), Ruffini corpuscle receptors (touch) + free nerve endings around hair follicles (hair movement) 45. What are the 4 hair - shaft (visible part) structures of the - root + follicle (below the surface) skin? - arrector pili muscle - hair root nerve plexus 46. What is the arrec- smooth muscle in dermis tor pili muscle? 47. What does the ar- - contracts with cold/fear rector pili muscle - forms goosebumps when hair is pulled vertically do? 48. What does the hair detects hair movement root nerve plexus do? 49. What are the func- - prevents heat loss tions of hair? - decreases sunburn 5/7 50. What are the 4 skin - sebaceous (oil) glands glands? - sudoriferous (sweat) glands - ceruminous (wax) glands - mammary (milk) glands 51. What is the seba- secretory portion in the dermis ceous (oil) gland? 52. What is sebum a combination of? - cholesterol - lipids - proteins - salts 53. What does sebum - keeps hair + skin soft do? - protects from UV light - reduces water loss through the skin - transports fat-soluble antioxidants (e.g. like vitamin E) to the skin surface 54. Why is sebum slightly acidic? inhibits the growth of bacteria + fungi 55. What is acne? - bacterial inflammation of glands - secretion stimulate by hormones at puberty 56. What are the 2 types of sweat glands? - eccrine - apocrine 57. Where are eccrine most areas of the skin (arms, face, legs etc.) sweat glands? 58. What do eccrine regular body temp with perspiration sweat glands do? 59. Where are apoc- armpit + pubic region rine sweat glands based? 60. responsible for body odour 6/7 What do apocrine sweat glands do? 7/7