Integumentary System Quiz

Integumentary System Overview

• Comprises skin, hair, nails, sweat and oil glands, and sensory receptors.
• Skin is the largest organ, constituting approximately 7% of body weight.
• Thickness varies from 0.5 mm (eyelids) to 4 mm (heels).

Skin Structure

• Epidermis: Avascular surface layer of stratified squamous epithelium.
• Dermis: Vascularized layer of connective tissue beneath the epidermis.
• Subcutaneous Layer (Hypodermis): Anchors skin to underlying fascia and contains pressure receptors.

Functions of the Integumentary System

• Regulates body temperature and protects against external insults.
• Senses environmental signals and assists in excreting/absorbing chemicals.
• Stores blood and energy, and synthesizes vitamin D.

Epidermis Specifics

• Contains keratinized stratified squamous epithelium with various cell types:
  • Keratinocytes: Produce keratin and lamellar granules for waterproofing.
  • Melanocytes: Synthesize melanin, protecting against UV light and preventing DNA damage.
  • Langerhans Cells: Phagocytic cells that respond to invaders.
  • Tactile Cells: Sensory cells that detect touch.
• Epidermis is segmented into strata:
  • Stratum Basale: Deepest layer with stem cells for replenishment.
  • Stratum Spinosum: Provides strength with thicker keratin filaments.
  • Stratum Granulosum: Contains dying cells, keratohyalin, and lamellar granules.
  • Stratum Corneum: Outermost layer of dead cells that shed easily.
  • Stratum Lucidum: Present only in thick skin, providing extra support.

Growth and Renewal

• Takes 4-6 weeks for new cells from stratum basale to reach the surface.
• Distance from nourishing blood supplies decreases access to nutrients, impacting cell viability.

Dermis Structure

• Composed of dense irregular connective tissue; has tensile strength.
• Papillary Region: Upper layer of areolar connective tissue; contains dermal papillae for touch and pain sensation.
• Reticular Region: Lower layer rich in thick collagen fibers, provides resistance to stretching and shear forces.

Fingerprints

• Formed by epidermal ridges in thick skin, contributing to grip and touch sensitivity.
• Unique patterns; fingerprints are generated by the underlying dermal papillae.

Skin Coloration

• Variations in skin color are due to melanin production; all individuals have similar melanocyte counts.
• Tans result from increased tyrosinase activity in melanocytes when exposed to UV light.
• Carotene can cause yellowish-orange tints in the skin, especially when accumulated.

Hair

• Protects the body and aids in sensation; found in various body locations.
• Composed of a hair root (embedded) and hair shaft (visible).
• Hair stratification includes:
  • Medulla: Innermost layer with pigmented cells.
  • Cortex: Main structure of hair.
  • Cuticle: Outermost layer made of flat keratinized cells.
• Hair follicles are surrounded by muscle tissue; arrector pili muscles enable hair to stand on end.

Skin Cancer Overview

• Basal Cell Carcinomas: Most common, primarily occur in the stratum basale (benign).
• Squamous Cell Carcinomas: Arise in stratum spinosum; more aggressive.
• Malignant Melanomas: Originating from melanocytes; highly dangerous.

Summary

• Integumentary system acts as a protective barrier while facilitating essential biochemical processes.
• Skin color diversity relates to varying melanin secretion with implications in UV protection.
• Efficient wound healing and understanding of skin cancers are critical for integumentary health.