Skin Anatomy & Physiology Flashcards

Which epidermal layer is characterized by the presence of keratohyalin granules visible on histology?

Answer: Stratum granulosum

The stratum granulosum is defined by the presence of keratohyalin granules containing profilaggrin, which contributes to cornification.

Elastic fibers in the dermis are composed primarily of which protein?

Answer: Elastin

Elastic fibers consist primarily of elastin protein cross-linked with fibrillin microfibrils, allowing the skin to stretch and recoil.

Merkel cells in the epidermis are associated with:

Answer: Slow-adapting light touch mechanoreception

Merkel cells are slow-adapting mechanoreceptors in the stratum basale that detect sustained light touch, pressure, and texture.

The nail plate is composed primarily of:

Answer: Hard keratin (alpha-keratin)

The nail plate is made of hard, densely packed alpha-keratin filaments produced by the nail matrix cells.

Which skin structure serves as the primary barrier against ultraviolet radiation damage to deeper tissues?

Answer: Melanin in the epidermis

Melanin pigment produced by melanocytes and transferred to keratinocytes forms a protective cap over keratinocyte nuclei, absorbing and scattering UV radiation.

The stratum lucidum is found exclusively in which body locations?

Answer: Palms and soles

The stratum lucidum is an additional clear epidermal layer found only in the thick skin of palms and soles, providing extra protection in high-pressure areas.

Mast cells in the dermis play a central role in allergic and inflammatory skin reactions by releasing:

Answer: Histamine and other vasoactive mediators

Mast cell degranulation releases histamine, tryptase, and other mediators that cause vasodilation, increased vascular permeability, and pruritus in allergic reactions.