integument appendages

Appendage Structures of the Integument

  • Focus on hair, nails, and glands derived from the epidermis.

Learning Objectives

  • Identify skin appendages.

  • Discuss kinds of skin glands: sebaceous and sudoriferous.

  • Describe structure of nails and hair.

  • Reference Saladin book: Hair and nails (pp. 184-189) and cutaneous glands (pp. 189-192).

Hair

  • Hair follicles and shafts derived from the epidermis with visible darker stained epidermis surrounding hair follicles.

  • Hair Bulb: Broad end of hair follicle where hair growth occurs.

    • Contains epithelial root sheaths.

    • Structure includes inner medulla and outer cortex.

  • Epithelial Root Sheath: Dips into dermal papillae containing blood vessels.

    • Vital for hair nourishment since hair itself is avascular (no blood vessels).

  • Hair Matrix: Contains mitotically active cells close to the blood vessel in the dermal papilla; these cells divide to push older cells away, resulting in hair growth.

  • Cells in hair below the skin and visible hair are dead due to distance from blood supply.

  • Male Pattern Baldness: Characterized by specific bald patterns, affected by testosterone and genetics; hair can be transplanted in treatments.

  • Hirsutism: Excessive hair growth in undesirable areas, often due to hormonal imbalances or medications.

Nails

  • Nails serve primarily fine motor functions rather than protection.

  • Composed of tightly packed, keratinized cells similar to those in the skin.

  • Nail Structure:

    • Nail fold, nail bed, and nail matrix are present.

    • Nail matrix contains mitotically active cells, pushing older cells away, enabling nail growth.

  • Epidermis thickens at nail fold, with blood vessels located in the dermis.

Glands

  • Sudoriferous (Sweat) Glands: Two types

    • Eccrine Glands:

      • Coiled glands in the dermis with ducts that open at sweat pores on skin surface.

      • Secrets primarily water and salts for evaporative cooling.

      • Widely dispersed; particularly abundant in palms and soles.

    • Apocrine Glands:

      • Located in the groin, armpits, and facial hair areas; ducts lead to hair follicles.

      • Secretions rich in fatty acids, which can lead to body odor when broken down by bacteria.

  • Sebaceous Glands:

    • Secretes sebum (oily secretion) that lubricates hair and skin; ducts lead to hair follicles.

    • Operates via holocrine secretion (whole cell death contributes to secretion).

    • Blocked ducts can lead to acne, pimples, or bigger issues like boils.

Conclusion

  • Introduced the basic structures of hair, nails, and their respective glands while connecting them to skin anatomy and physiological functions.

  • Next topic: tissue repair.