Introduction of Dermatology

17.06.21 06:45

Anatomy of Skin

  • Largest organ system
  • Measures about 2.12 sq m
  • Weighing 4-5 (16% body weight) kg
  • Presence of sebaceous, eccrine glands, hair, nails, mucous membrane

Embryology

  • All constituents are derived from ectoderm and mesoderm
  • Ectoderm and mesoderm begin to proliferate and differentiate at 4th week of intrauterine life
  • The specialized structures of skin, teeth, hair, nails and glands begin to appear at this time

Layers of skin

  • Epidermis
  • Dermis
  • Hypodermis

Epidermis:

Deep -> superficial Boy, - Basale Some - Spinosum Girls - Granulosum Look - Lucidum Cute - Corneum

Made of stratified squamous epithelium

Stratum basale
  • a.k.a Stratum germinatum
  • Single layer of columnar cells (central nucleus)
Stratum spinosum
  • Thickest layer of epidermis

  • Spine like process

  • A.k.a Prickle cell layer

  • Spine-like processes are desmosomes
    Desmosomes are intraepidermal intercellular connection [[Pasted image 20210618154645.png]]

  • ** Applied aspect** Pemphigus group of disorder - antibodies targets desmosomes leading to lysis of attachment

    Above 2 layers together are the Malphigian layer - a layer in which cells continuously divide

Stratum granulosum
  • Keratohyaline granules -> Profilagrin -> Filagrin
  • Lamellar granules a.k.a Cementosomes/Odland body
    Responsible for production of lipid -> barrier function of skin
Stratum lucidum

Translucent layer

  • Eleidin granules are present
  • Present only in palms and soles
Stratum corneum
  • Flat cells
  • Fully keratinised
  • Nucleus is not present - dead
Transitional changes form S. Basale -> S. corneum:

  • Shape -> Flattening
  • Nucleus -> Disappearance in S. corneum
  • Keratin -> increases
  • Water -> decreases (dehydration)
  • Epidermal transitional time (basale -> corneum): 28 days/4 weeks
    In disorders like Psoriasis ETT is 3 to 5 days