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Hair follicle

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

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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

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  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

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