Skin: Accessory Structures, Glands, and Repair

Hair and Accessory Structures

  • Arrector Pili Muscle

    • Involuntary smooth muscle.

    • Causes hairs to stand up, producing "goose bumps."

  • Sebaceous Glands

    • Lubricate hair.

    • Inhibits bacteria growth.

  • Hair Production

    • Begins at the base of hair follicle, deep in dermis.

    • Hair papilla contains capillaries and nerves.

    • Hair bulb produces hair matrix: forms hair structure, pushes hair up, and keratinizes it.

    • Hair grows back if hair matrix is not removed.

Glands

  • Sebaceous (Oil) Glands

    • Holocrine glands secreting sebum.

    • Discharge directly onto skin surface.

    • Sebum lubricates and protects epidermis, inhibits bacteria.

  • Merocrine (Eccrine) Sweat Glands

    • Widely distributed, especially on palms and soles.

    • Discharge directly onto skin surface.

    • Functions: cools skin, excretes water/electrolytes, flushes microorganisms/chemicals.

  • Apocrine Sweat Glands

    • Found in armpits, around nipples, and groin.

    • Secrete products into hair follicles.

    • Produce sticky, cloudy secretions; breakdown causes odors.

  • Ceruminous Glands

    • Modified sweat glands.

    • Produce cerumen (earwax).

    • Protect the eardrum.

Nails

  • Protect fingers and toes.

  • Made of dead cells packed with keratin.

  • Production occurs in nail root (deep epidermal fold near bone).

Wound Healing and Tissue Repair

  • Phases of Wound Healing:

    1. Inflammation

    2. Migration phase

    3. Proliferative phase

    4. Maturation phase

  • Fibroblasts produce scar tissue.

  • Keloid Scar: Excessive collagen production; growth exceeds wound boundaries; tumor-like appearance.

Skin Cancer

  • Three major types:

    • Basal cell carcinoma

    • Squamous cell carcinoma

    • Melanoma