Questions and Answers
Which layer of the epidermis is the most superficial?
Which cells in the epidermis are primarily responsible for synthesizing melanin?
What is the hallmark feature of Langerhans cells?
Which epidermal layer is known for providing mechanical strength to the skin?
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What is the primary function of Merkel cells in the skin?
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How long is the skin's epidermal proliferation time or doubling time?
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Which type of cells in the epidermis are derived from neural crest cells?
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What type of keratin is characterized as strong due to disulfide bonds and is primarily found in nails and hair?
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What is the primary defect associated with piebaldism?
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Which phase of hair growth is characterized by a resting state lasting approximately 3 months?
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In which condition would you primarily observe 'exclamation mark' hair?
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Which type of alopecia is specifically linked with systemic stressors like pregnancy?
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What is the primary site for the nevus with unilateral symmetry that affects the trigeminal nerve distribution?
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Which hair growth phase follows the anagen phase and lasts approximately 3 weeks?
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What primary feature distinguishes male androgenetic alopecia from female androgenetic alopecia?
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What is the characteristic finding in a Tzanck smear for diagnosing herpes genitalis?
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Which condition is characterized by congenital white patches due to vasoconstriction?
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Which statement accurately describes the role of Chlamydia trachomatis in non-gonococcal urethritis?
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In the context of pigmentary disorders, which statement regarding freckles is correct?
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What is the main genetic characteristic of Becker's nevus?
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What distinguishes lentigines from other pigmented lesions?
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Which condition is associated with spontaneous resolution of slate grey colored lesions?
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What is the defect associated with albinism?
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How is hypertrophy of melanocytes best described in the context of freckles?
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Study Notes
Skin Structure
- Skin is the largest organ composed of two main layers: Epidermis and Dermis.
- Epidermis consists of five layers: Stratum corneum, Stratum lucidum, Stratum granulosum, Stratum spinosum, and Stratum basale.
- Stratum corneum is the most superficial layer; it is immature in preterm infants for 2-3 weeks.
Skin Layers and Their Cells
- Keratinocytes: Make up 90% of the epidermis; hallmark is presence of keratin filaments. Hard keratin is found in nails and hair, while soft keratin is found in skin.
- Melanocytes: Located in Stratum basale, derived from neural crest cells, responsible for melanin production in melanosomes.
- Merkel Cells: Found in Stratum basale, function as slow-adapting mechanoreceptors, derived from ectoderm.
- Langerhans Cells: Present in Stratum spinosum, serve as antigen-presenting cells; characterized by Birbeck granules and markers CD1a and S100.
Epidermal Proliferation
- Skin doubling time is approximately 4 weeks.
Non-gonococcal Urethritis
- Caused by Chlamydia trachomatis (most common), Ureaplasma, Mycoplasma, and Trichomonas.
- Symptoms include scanty mucoid discharge and numerous PMNs.
- Treatment options include Azithromycin or Doxycycline.
Herpes Genitalis
- Primarily caused by HSV-2 (90%); presents as tender ulcers following vesicle rupture.
- Diagnosis involves Tzanck smear identifying multinucleated giant cells.
- Treatment typically includes Acyclovir.
Pigmentary Disorders
- Melasma: Symmetrical hyperpigmented macules; can occur in pregnancy (chloasma) or after Chikungunya.
- Freckles: Normal melanocyte count but increased activity; associated with Xeroderma Pigmentosa.
- Lentigines: Normal melanocyte activity; can be seen in Peutz-Jegher syndrome, which presents with mucosal lentigines.
- Mongolian Spot: Blue-grey lesions found in infants, typically resolve spontaneously.
- Becker's Nevus: Acquired unilateral hypertrichosis, generally on the chest and upper shoulder.
- Congenital Melanocytic Nevi: Well-demarcated; giant nevi (>20 cm) have a 2.5% melanoma risk.
Disorders of Hypo/Depigmentation
- Albinism: Due to tyrosinase deficiency; types include ocular and oculocutaneous.
- Piebaldism: Autosomal dominant condition with white forelock due to neural crest defect.
- Nevus pigmentosus: Issues with melanosome transfer to keratinocytes.
- Vitiligo: Autoimmune disorder leading to melanocyte destruction.
- Nevus of Nota: Unilateral, associated with trigeminal nerve V1, V2.
- Nevus of Ito: Unilateral, involving supraclavicular nerve, found on shoulders and scapular regions.
Skin Appendages
- Skin appendages include hair, nails, and glands.
Hair Cycle Phases
- Anagen: Growing phase lasting about 3 years.
- Catagen: Involution phase lasting about 3 weeks.
- Telogen: Resting phase lasting about 3 months.
Alopecia Types
- Non-Scarring Alopecia: Includes alopecia areata, patch-induced by stressors, and diffuse patterns from systemic events.
- Alopecia Areata: An autoimmune condition resulting in circular patches of hair loss with 'exclamation mark' hair indicating tapering ends.
- Treatment options include intralesional corticosteroids for localized cases and systemic treatment for extensive disease.
- Male Androgenetic Alopecia: Characterized by fronto-temporal recession and vertex balding.
- Female Androgenetic Alopecia: Frontal hairline generally remains intact.
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Description
Test your knowledge on the layers of skin and their functions in this dermatology quiz. Explore key concepts about the epidermis and dermis, including specifics like the stratum corneum and its significance in different life stages. Perfect for college students studying dermatology.
