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Integumentary system

Not medically reviewed · Content last updated · 1 min read ·

This is the date the draft was written, not a medical review date.

The integumentary system is the skin and its appendages, the largest organ of the body. It forms a protective barrier against injury, microbes and water loss, and takes part in thermoregulation, sensation and vitamin D synthesis.

Terminologia Anatomica (Latin): Integumentum commune

Components

The skin has an epidermis (keratinised stratified squamous epithelium), a dermis of connective tissue and a subcutaneous hypodermis. Appendages are hair follicles, sebaceous and sweat glands and nails, and the skin contains melanocytes, Langerhans cells and sensory receptors.

Function

The epidermis provides mechanical, chemical and microbial protection and limits water loss, while sweating and cutaneous blood flow regulate body temperature. Skin senses touch, pressure, temperature and pain, and synthesises vitamin D3 on exposure to ultraviolet B.

Clinical correlations

Dermatitis, infections, psoriasis, burns, pressure injuries and skin cancers (basal cell, squamous cell carcinoma and melanoma) are common. Burn depth and body-surface-area estimation guide assessment, and management follows local guidelines.

Common exam points

  • Five layers of the epidermis from deep to superficial: basale, spinosum, granulosum, lucidum (thick skin only), corneum.
  • Thick skin (palms and soles) versus thin skin, and the distribution of hair follicles.
  • Dermatomes and cutaneous innervation as a basis for sensory examination.
  • Superficial, partial-thickness and full-thickness burns with the rule of nines for surface-area estimation.
  • Skin cancer types and the role of ultraviolet exposure.

References

  1. Drake RL, Vogl AW, Mitchell AWM. Gray's Anatomy for Students. Elsevier — Tier 3 (textbook)
  2. Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy. Wolters Kluwer, 8th edition (2018) — Tier 3 (textbook)
  3. Pawlina W. Histology: A Text and Atlas. Wolters Kluwer, 8th edition (2020) — Tier 3 (textbook)

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