Skin: Integumentary System

Epidermis - Epithelial Tissue

• S. Corneum - outermost, thickest layer; dead flattened (squamous) cells; filled with keratin (hard); exfoliate

• S. Lucidum - translucent; not always present; in thick skin only (hands/feet)

• S. Granulosum - grainy appearance - releases lipids (waterproof

• S. Spinosum - spiny appearance due to desmosomes (strength) - cell division decreases

• S. Basale - deepest layer; single layer cuboidal cells, increase in cell division due to nourishment from dermal blood vessels

  • 5 cells found in this layer

    • stem cells - divide to become differentiated cells

    • keratinocytes - make keratin

    • melanocytes - make melanin

    • langerhans - alert immune system

    • merkel - sense of touch

Dermis (Connective Tissue) (Thickest Layer)

• Papillary

  • Areolar (Loose) Connective Tissue

  • Friction Ridges (Fingerprints) - create friction

• Reticular

  • Dense Connective Tissue

  • Skin Tension Lines (bundles of fibers)

  • Wounds and Surgical Cuts better when parallel

• Also includes:

  • Blood Vessels

  • Nerve Cells

  • Sweat Glands

  • Sebaceous Glands

  • Hair Follicles

Hypodermis/Subcutaneous (Connective Tissue)

• Adipose (Fat) Tissue - insulation and protection

• Major Blood Vesssels

• Not a true layer of skin