4.1.2. Glands, Hair Follicles, and Skin Appendages

💡 First Principle: The appendages of the skin — glands, follicles, and nails — are not separate structures. They originate in the dermis and extend through the epidermis to the surface. Understanding their location and function explains many skin conditions and treatment considerations.

Sebaceous (Oil) Glands:

• Located in the dermis, attached to hair follicles
• Produce sebum (skin's natural oil/lubricant)
• Sebum travels up the hair follicle to the skin surface
• Overactive sebaceous glands → oily skin, clogged pores, acne
• Found everywhere except palms and soles
• Largest and most active on the face, chest, and back (the "T-zone" area)

Sudoriferous (Sweat) Glands:

• Two types:
  • Eccrine glands — found over most of the body; produce watery sweat for thermoregulation
  • Apocrine glands — found in armpits, groin; become active at puberty; produce thicker secretion (related to body odor)
• Sweat exits through pores directly on the skin surface

Hair Follicles:

• Tube-like structures in the dermis that anchor each hair
• Each follicle has an associated sebaceous gland
• Hair growth occurs at the follicle's base (the bulb) — relevant for hair removal treatments
• Hair removal methods target the follicle at different depths

Melanocytes:

• Located in the stratum germinativum
• Produce melanin — the pigment that gives skin its color and provides UV protection
• Damaged melanocytes lead to uneven pigmentation (hyperpigmentation, hypopigmentation)

⚠️ Exam Trap: Sebaceous glands are associated with hair follicles — not with sweat pores. The gland empties into the follicle, which is why comedones (clogged pores) involve the follicle opening, not the sweat pore.

Reflection Question: A client has extremely oily skin on their T-zone but dry skin on their cheeks. Based on what you know about sebaceous glands, what is the underlying cause of this pattern?