Chapter 8 Skin Physiology

1. Chapter 8Skin Physiology

2. Key Terms • Skin Physiology- study of the skins function • Skin Histology- microscopic study of the skin’s tissue • Dermatology- study of skin • Dermatologist- MD who specializes in the skin, hair and nails

3. Functions of the Skin • Protection- shields internal tissues from external elements • Absorption- certain types of ingredients are allowed to enter the skin • Secretion- sebum is secreted through the hair follicle giving us an acid mantle • Excretion- sweat allows our body to rid itself of waste • Regulation- 98.6 by goosebumps, shivering, blood flow increases and sweat production • Sensation - nerve ending that contain stimuli

4. Parts of the Cell

5. Mitosis Steps: 1.Nucleus Splits 2. Cytokinesis 3.Cell Membrane split Resulting: in 2 daughter cells

6. 3 Main Divisions of the Skin

7. What makes up the skin? • A Protein Called KERATIN • Hard Keratin – Hair and Nails • Soft Keratin – Skin Keratin is made of these Chemical Elements: C – Carbon O- Oxygen H- Hydrogen N- Nitrogen S- Sulfur

8. Keratin • Keratincytes produce large amounts of the protein keratin, once that is made is forms fibers. The tightly interlocked cells filled with keratin fibers are surrounded by keratohyalin (a protein substance that forms keratin)

9. The Epidermis • Outermost layer of the skin • NO blood vessels in this layer • Epidermis cells are called epithelial cells • Is composed of keratinocytes, which consist of the protein keratin • Like the shingles on a roof • Made up of 5 layers

11. Stratum Corneum • “Horny Layer” • Toughest layer of the epidermis • Keratinization ends. (The chemical process of living cells into dead protein cells) • Desmosomes keep these dead cells connected • These dead protein cells remain in this layer for about 28 days. • Squamous Cells- these serve as protection and aids in moisture balance by acting as a barrier

12. Stratum Corneum

13. Stratum Lucidum • Clear transparent layer • Thickest on the palms and soles • Epidermal ridges and whorls (fingerprints and traction) • Prism

14. Stratum Granulosum • “Granular Layer” • Keratinization begins ( the nucleus and other organelles begin to disintegrate and die as they are traveling up through this layer and those above) • Cells continue to move upward through this layer

15. Stratum Granulosum

16. Stratum Spinosum • “Spiny Layer” • 8-10 cell layers thick • Langerhans cells – these cells alert the T-cells of antigens by displaying a key part of the antigen material on it’s cellular membrane • Not present in all areas of skin

17. Stratum Germinativum • “Basal Layer” • Mitosis occurs and cells take 25-30 days to travel from this layer to the stratum corneum. • Only living layer in the epidermis • Hemidesmosomes – help the epidermis attach the dermis, intercellular cement. Which is called the basement membrane • Merkel Cells – touch and sensory receptors • Melanin present in this layer

18. Melanin vs. Pigment • Melanin is the body’s natural coloring • Pigment refers to natural or artificial coloring • 3 things impact a persons skin color: • The amount of melanin • The type of melanin (eumelanin and pheomelanin • The distribution of melanin

19. The Dermis • “True Skin” • 25 x thicker than the epidermis • Connective tissue • Fibroblast cells – formation of collagen (Structure) and elastin (Stretch) • 70% of the dermis is made up of collagen • Elastin should stretch to 2x its size • Mast cells- produce histamines

20. Collagen and Elastin

21. Dermis

22. Papillary Layer • Rich in Blood Vessels • Provides nutrients to the epidermis with fingerlike projections • House sensory nerve ending • Thermo receptors- hot or cold • Mechano receptors- movement • Tactile receptors- gentle touch or pressure

23. 4 main receptors for sensation • Meisner’s Corpuscles- Light pressure and cold • Ruffini’s Corpuscles – Longterm pressure and heat • Pacinian Corpuscles – Deep pressure and pain • Krause’s End Bulbs – Pressure and pain receptors

24. Reticular Layer • Contains fewer blood vessels • Contain the sweat and oil glands

25. Sudoriferious Glands • Produce sweat (H2O, urea, electrolytes, and lactic acid) • Controlled by the nervous system • Has its own pore opening • 2 types • Apocrine – arms, genitals and nipples, odorless substance triggered by emotion • Eccrine- throughout the body, influenced by the sympathetic nervous system which produce physiological responses • What causes body odor then?

26. Sebaceous Glands • Produce sebum (oil) • All over the body except the palms and soles • Attached to the hair follicle • Influenced by the male hormone androgen • Helps create Acid Mantle

27. The Subcutaneous Layer • Composed of adipose tissue (fat) • Body’s shock absorber • Gives contour and shape • Serves as an emergency reservoir for nutrients, water and energy

28. pH Scale – (Potential Hydrogen)

29. CTR – Cell Turnover Rate • Factors: • Age • Sun Exposure • Use of exfoliating agents • Skin conditions

30. Exfoliation • Manual – physical process of removing dead cells from the surface of the skin • Chemical- using a chemical reaction to remove the dead cells from the surface of the skin.

31. Transdermal Penetration • The process of skin absorption • 4 ways products are absorbed: • Pores • Follicles • Intercellular cement • Oil and sweat glands • Factors affecting skin absorption: • Condition of the stratum corneum • Hydration level • Oiliness of the skin • Size of the products molecules • Temperature of the skin

32. Skin Disorders

33. Primary Lesions • Macule- large freckle • Wheal- raised pink swelling, caused by an allergic reaction • Papule- does not contain pus, red and elevated • Pustule-(zit) filled with bacterial fluid and pus • Vesicle- blister • Nodule- solid mass within the skin • Cyst- abnormal membrane sac containing a gaseous liquid or semi solid substance

34. Secondary Lesions • Crust- scab • Excoriation- scratches to surface of the skin • Scale- shedding of dead skin cells • Scar- formation resulting from lesion • Fissure- crack or line in the skin • Ulcer- open lesion

35. Dermatitis “inflammation of the skin” • Atopic- genetic, have sensitivities, temp changes aggravate, avoid hot showers and baths • Contact- rash caused by allergic reaction • Seborrheic- form of eczema, pink, yellow patches

37. Psoriasis • Genetic • Excess of thick, scaly, silvery skin • Caused by increased growth of skin cells • Can become thick requiring exfoliation

38. Psoriasis

39. Eczema • Dry or moist lesions • Eruption of small vesicles and watery discharge and then dries • Not contagious but refer to MD

40. Eczema

41. Infections • Herpes simplex – viral, no cure, contagious • Herpes Zosters- Shingles

42. Infections • Impetigo- staph infection, honey yellow crusted lesion • Tinea- ringworm, contagious fungal disease

43. Infections • TineaCorporis- fungal infection on the arms, trunk and legs • TineaVericolor- tricolor yeast infection

44. Infections • Verruca- most common tumor, Warts, (HPV) • Candida Albicans – yeast infection • Pink Eye- inflammation of the membrane of the eyelid

45. Sebaceous Disorders • Asteatosis- reduced sebum production • Seborrhea- excess secretion of sebum • Steatoma-harmless cyst filled with sebum • Furnucle- boil • Carbuncle- group of boils

46. Rosacea • Chronic inflammatory condition • Couperose dilated and inflamed • Can be accompanied with acne type papules and pustules • Prevalent in fair skin types and women • A more severe type is rhinophyma • Condition worsened by acidic and spicy food, temp changes, alcohol and stress • Cause is unknown • Topical Vit C therapy can be helpful

47. Rosacea

48. Acne • Hormonal changes and genetics are 2 major causes • Can be caused by stress, medications, humid environment, and surface irritation • Is always caused by excessive androgen • The follicle lining sheds more rapidly and the production of sebum increases, the combination plugs the opening of the follicle and blocks oxygen from entering • Bacteria contributes to the inflammation • Retention hyperkeratosis- accumulation of cells that adhere to the follicle

49. Types of Acne • Open Comedone- blackhead, has been oxidized • Closed comedone- whitehead, not exposed to oxygen • Papule- does not contain pus • Pustule- contains pus • Milia- pearly white enclosed cyst, can be lanced. • Nodular Cystic Acne- hard lesions found deep in the skin. Severe form

50. Grades of Acne