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  • Overview
  • Layers and cells
  • Pigmentation and UV
  • Appendages
  • Thermoregulation
  • Wound healing
  • Burns (survey)
  • Worked micro‑examples
  • Pitfalls
  • Practice prompts
  • References

Anatomy and Physiology - Integumentary System

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Type: Study
Divisions: B, C
Participants: Up to 2
Approx. Time: 50 minutes
Allowed Resources: Binders/notes allowed per rules; non‑programmable calculator as permitted.

Overview

The integumentary system provides barrier, thermoregulation, sensation, and metabolic functions. Master topics include epidermal turnover, dermal structure, appendages, and wound healing.

Layers and cells

  • Epidermis (avascular): stratum basale (stem cells, melanocytes), spinosum (desmosomes), granulosum (keratohyalin), lucidum (thick skin), corneum (keratinized). Langerhans (APCs) in spinosum.
  • Dermis: papillary (loose connective tissue, capillaries, Meissner corpuscles) and reticular (dense irregular CT, collagen/elastin, Pacinian corpuscles). Hypodermis: adipose, insulation.

Pigmentation and UV

  • Melanocytes produce melanin transferred to keratinocytes; eumelanin vs pheomelanin; tanning phases; photoprotection; vitamin D synthesis in keratinocytes (UVB‑dependent).

Appendages

  • Hair follicles, nails, glands: eccrine (thermoregulatory sweat), apocrine (scent), sebaceous (sebum). Distribution and control (sympathetic cholinergic for eccrine).

Thermoregulation

  • Vasodilation/vasoconstriction of dermal vessels; sweating; arrector pili (minor).

Wound healing

  • Phases: hemostasis → inflammation → proliferation (granulation tissue, re‑epithelialization) → remodeling (collagen maturation, tensile strength rises). Hypertrophic vs keloid scarring distinctions.

Burns (survey)

  • Degrees: superficial (epidermis), partial thickness (into dermis), full thickness. Rule of nines for surface area estimation (adults).

Worked micro‑examples

  1. Barrier disruption
  • Stratum corneum compromise increases transepidermal water loss; infant skin differences increase susceptibility.
  1. UV exposure
  • Excess UVB damages DNA (pyrimidine dimers); p53‑mediated cell cycle arrest; long‑term risk for non‑melanoma skin cancers.
  1. Sweat gland function
  • Eccrine hypofunction impairs heat dissipation → heat exhaustion risk; hyperhidrosis management conceptually.

Pitfalls

  • Confusing gland types and secretions; misplacing mechanoreceptors by layer.
  • Overlooking avascularity of epidermis (nutrient diffusion from dermis).

Practice prompts

  • Label epidermal layers and list cell types and functions per layer.
  • Compare eccrine vs apocrine glands and their regulation.
  • Outline wound healing stages and expected histology.

References

  • SciOly Wiki – Anatomy & Physiology (Integumentary)
  • OpenStax Anatomy & Physiology (Integumentary system)