Integumentary System Study Overview

Sep 2, 2024

Lecture on Integumentary System

Important Announcements

  • This is the last chapter of the current unit.
  • Exam on Thursday covering both lecture and lab materials.
  • Review study guide and lab exam materials.

Integumentary System Overview

  • The skin is the main component of the integumentary system, comprising 10-15% of total body weight.
  • Dermatology is the study of the skin.
  • The skin consists of two main layers:
    • Epidermis: Outermost layer.
    • Dermis: Thicker layer beneath containing most structures.
  • Hypodermis (subcutaneous layer): Not technically part of the skin but anchors skin to underlying structures.

Important Structures of the Skin

  • Epidermis Layers: Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum (only in thick skin), and stratum corneum.
  • Dermis Features: Papillary layer (superficial) and reticular layer (thicker, contains collagen bundles).
  • Hypodermis: Contains adipose tissue and blood vessels.

Key Components in Skin

  • Dermal Papillae: Increase surface area between epidermis and dermis.
  • Sweat Glands: Eccrine (directly to skin) and Apocrine (armpits, anal, areola regions).
  • Sebaceous Glands: Produce sebum, moisturize skin/hair.
  • Nerve Endings: Tactile (light touch), free nerve endings, lamellated corpuscles (pressure).

Functions of the Integumentary System

  • Protection: Against mechanical trauma, pathogens, and UV radiation.
  • Sensation: Nervous system receptors in the skin.
  • Excretion: Waste products through sweat.
  • Vitamin D Synthesis.
  • Thermoregulation: Hypothalamus regulates body temperature.

Epidermis Details

  • Keratinocytes: Main cells of the epidermis, produced in the stratum basale.
  • Dendritic Cells (Langerhans cells): Immune responses, found in stratum spinosum.
  • Merkel Cells: Light touch receptors, found in stratum basale.
  • Melanocytes: Produce melanin for UV protection, found in stratum basale.

Dermis Details

  • Papillary Layer: Contains dermal papillae, capillaries, and tactile corpuscles.
  • Reticular Layer: Contains dense connective tissue, elastic fibers, proteoglycans, and lamellated corpuscles.

Skin Markings

  • Epidermal Ridges: Fingerprints, from dermal ridges.
  • Tension Lines: Important for surgical incisions.
  • Wrinkles: Caused by age, UV exposure, expressions.

Melanin and Skin Color

  • Determined by melanin production.
  • Freckles: Increased melanin in the same number of cells.
  • Moles: More cells producing melanin.
  • Albinism: Lack of melanin production.
  • Tanning: No healthy tan; UV exposure increases skin cancer risk.

Accessory Structures

  • Hair: Shaft and root, with growth stages: anagen (growth), catagen (transition), telogen (resting).
  • Nails: Nail plate, nail matrix (growth area), lateral/medial nail folds.

Skin Glands

  • Sweat Glands: Eccrine and apocrine, plus ceruminous (earwax) and mammary (milk) glands.
  • Sebaceous Glands: Produce sebum, can cause acne.

Skin Conditions

  • Acne: Caused by clogged sebaceous glands.
  • Burns: First, second, third degree, can lead to dehydration and infection.

Skin Cancer

  • Basal Cell Carcinoma: Most common, less likely to spread.
  • Squamous Cell Carcinoma: Second most common, more likely to spread.
  • ABCD Rule for Skin Cancer: Asymmetry, Border irregularity, Color variation, Diameter (>6mm).

Study Tips

  • Review structures of the skin on diagrams.
  • Practice identifying accessories and glands on models.
  • Understand functions and disorders associated with the skin.