Lecture on Appendages of the Skin

Introduction

• Appendages: Structures associated with the skin, primarily in the dermis.
• Major Types: Two major gland classifications in the dermis.

Types of Glands

Eccrine Glands

• Structure: Snake-like, sinusoidal with a duct leading to skin surface (sweat pore).
• Function: Responsible for perspiration; found in palms, soles, forehead.
• Secretion: Water, salts, electrolytes, acid wastes (e.g., uric acid), and dermcidin.
  • Dermcidin: Protein that kills bacteria on the epidermis.
  • Acidity: Sweat is slightly acidic providing protection.

Sebaceous Glands

• Association: Always with hair follicles.
• Function: Secretes sebum through hair follicles to lubricate skin/hair and acts as a bactericide.

Sudoriferous Glands

• Types:
  • Eccrine glands: Most common, discussed above.
  • Apocrine glands: Found in axillary/anogenital areas, secretes sweat plus lipids/proteins.
    • Response: Stress and sexual stimulation.
    • Body Odor: Decomposition by bacteria of lipids/proteins creates odor.

Other Sudoriferous Glands

• Ceruminous Glands: Produce earwax.
• Mammary Glands: Secrete milk.

Nails

• Composition: Hard keratin, scale-like modifications of the epidermis.
• Nail Matrix: Growth starts below proximal nail fold.
• Significance: Important for upcoming case study.

Hair

• Composition: Keratin in concentric circles, same protein in skin and nails.
• Growth: Starts in hair bulbs; only actively mitotic cells.
  • Structure: Grows from basal level superficially as dead cells.
• Erector Pili Muscle
  • Attachment: To epidermis and hair shaft.
  • Function: Involuntary muscle present in every hair.

Conclusion

• Summary: Skin appendages include various glands, nails, and hair, each with distinct functions and compositions, primarily involving different forms of keratin.