02. Hair nails and skin glands – Practice Quiz

Hair, Nails, and Skin Glands: Integumentary Appendages and Secretions

Integumentary appendages—hair follicles, nails, sebaceous glands, and sweat glands—are embryonic downgrowths of the epidermis specialized for sensory reception, mechanical protection, surface lubrication, and thermoregulation. This questionset explores their structural biology, developmental cycles, and neuroendocrine control.

Key Learning Areas

• Hair follicle anatomy: dermal papilla, hair matrix, medulla, cortex, cuticle, root sheaths, and the glassy membrane.
• Hair growth cycle: anagen (active mitosis and lengthening), catagen (apoptotic regression of the lower follicle), telogen (quiescence), and exogen (active shedding).
• Arrector pili muscle: sympathetic noradrenergic innervation, piloerection (cutis anserina), and sebum extrusion.
• Nail unit architecture: nail matrix (generating hard keratin), eponychium (cuticle), hyponychium (infection seal), lunula, and the sterile nail bed.
• Cutaneous glands: sebaceous glands (holocrine secretion of squalene, wax esters, and triglycerides under androgen control).
• Sweat gland biology: eccrine glands (sympathetic cholinergic, hypotonic sweat, thermoregulation, dermcidin) vs. apocrine glands (merocrine secretion, puberty onset, axillary/anogenital distribution, bacterial odor generation).

Cover image credit: Photo by Paul Siewert on Unsplash.