Hair follicle - PowerPoint PPT Presentation

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Hair follicle
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Hair follicle

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  1. Hair follicle Hoban

  2. Associated Hair Structures • Hair follicle • Dermal and epidermal sheath surround hair root • Arrectorpilli • Smooth muscle • Pulls hairs upright when cold or frightened • Sebaceous gland • Sweat gland Figure 4.7a Hoban

  3. Scanning electron micrograph showing a hair shaft emerging from a follicle at the skin surface Hoban

  4. Hoban

  5. Appendages of the Skin • Nails • Scale-like modifications of the epidermis • Heavily keratinized • Stratum basale extends beneath the nail bed • Responsible for growth • Lack of pigment makes them colorless Hoban

  6. Nail Structures • Free edge • Body is the visible attached portion • Root of nail embedded in skin • Cuticle is the proximal nail fold that projects onto the nail body Figure 4.9 Hoban

  7. Hoban

  8. Hoban

  9. In need of a manicure? Hoban

  10. Skin Homeostatic Imbalances • Infections • Athletes foot (tineapedis) • Caused by fungal infection • Boils and carbuncles • Caused by bacterial infection • Cold sores • Caused by virus Hoban

  11. Athlete’s foot Hoban

  12. Foruncles and boils Hoban

  13. Herpes simplex 1 Cold sores Hoban

  14. Skin Homeostatic Imbalances • Infections and allergies • Contact dermatitis • Exposures cause allergic reaction • Impetigo • Caused by bacterial infection • Psoriasis • Cause is unknown • Triggered by trauma, infection, stress Hoban

  15. Contact dermatitis Hoban

  16. Impetigo Hoban

  17. Psoriatic dermatitis Hoban

  18. Psoriasis Hoban

  19. Hoban

  20. Skin Homeostatic Imbalances • Burns • Tissue damage and cell death caused by heat, electricity, UV radiation, or chemicals • Associated dangers • Dehydration • Electrolyte imbalance • Circulatory shock Hoban

  21. Rule of Nines • Way to determine the extent of burns • Body is divided into 11 areas for quick estimation • Each area represents about 9% of total body surface area Figure 4.11a Hoban

  22. Hoban

  23. Severity of Burns • First-degree burns • Only epidermis is damaged • Skin is red and swollen • Second degree burns • Epidermis and upper dermis are damaged • Skin is red with blisters • Third-degree burns • Destroys entire skin layer • Burn is gray-white or black Hoban

  24. Hoban

  25. 2nd& 3rd degree burns Hoban

  26. 1st degree burns Hoban

  27. 3rd degree burn Hoban

  28. 3rd degree burn Hoban

  29. Critical Burns • Burns are considered critical if: • Over 25% of body has second degree burns • Over 10% of the body has third degree burns • There are third degree burns of the face, hands, or feet Hoban

  30. Skin Cancer • Cancer – abnormal cell mass • Classifed two types • Benign • Does not spread (encapsulated) • Malignant • Metastasized (moves) to other parts of the body • Skin cancer is the most common type of cancer Hoban

  31. Skin Cancer Types • Basal cell carcinoma • Least malignant • Most common type • Arises from statumbasale Hoban

  32. Basal cell carcinoma Hoban

  33. Skin Cancer Types • Squamous cell carcinoma • Metastasizes to lymph nodes if not removed • Early removal allows a good chance of cure • Believed to be sun-induced • Arises from stratum spinosum Hoban

  34. Squamous cellcarcinoma Hoban

  35. Squamous cell carcinoma Hoban

  36. Hoban

  37. Skin Cancer Types • Malignant melanoma • Most deadly of skin cancers • Cancer of melanocytes • Metastasizes rapidly to lymph and blood vessels • Detection uses ABCD rule Hoban

  38. Malignant melanoma Hoban

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  42. Still want to go tanning? Hoban

  43. ABCD Rule • A = Asymmetry • Two sides of pigmented mole do not match • B = Border irregularity • Borders of mole are not smooth • C = Color • Different colors in pigmented area • D = Diameter • Spot is larger then 6 mm in diameter Hoban

  44. Developmental Aspects of Skin • Fetal life • Lanugo- downy hair develops at 5th month of gestation; shed by birth • Vernixcaseosa- white, cheesy-looking substance, from sebaceous glands, protects baby’s skin in amniotic sac • milia- oil buildup in sebaceous glands on baby’s nose and forehead; gone by 3rd week after birth Hoban

  45. Adolescence • Skin and hair become oily • Acne- subsides in early adulthood Hoban

  46. Old age • Subcutaneous tissue decreases; leads to cold intolerance • Skin drier; itchy • Thins out; bruising • Skin sags due to decreased elasticity Hoban

  47. Too much sun? Hoban