Integumentary System: Skin Histology and Related Pathology

These vocabulary flashcards cover the major structural layers, cellular components, junctions, extracellular matrix elements, receptors, glands, vasculature, and pathologies discussed in the skin histology lecture notes.

Basal Cell Carcinoma

Most common malignant skin tumor; arises from cells of the stratum basale.

Squamous Cell Carcinoma

Malignant tumor originating from keratinocytes of the stratum spinosum.

Melanoma

Aggressive skin cancer derived from melanocytes.

Epidermis

Superficial epithelial layer of skin composed of stratified squamous keratinized epithelium.

Dermis

Connective-tissue layer beneath epidermis; forms papillary and reticular layers.

Hypodermis (Subcutis)

Loose connective tissue and adipose layer anchoring skin to underlying structures.

Stratum Basale

Deepest epidermal layer containing mitotic stem cells and keratin 5/14.

Stratum Spinosum

‘Prickle-cell’ layer rich in desmosomes and keratin 1/10.

Stratum Granulosum

Epidermal layer with keratohyaline granules and abundant filaggrin.

Stratum Lucidum

Thin translucent layer present in thick skin between granulosum and corneum.

Stratum Corneum

Outermost layer of dead, flattened, keratinized cells forming the cornified envelope.

Hemidesmosome

Junction anchoring basal keratinocytes to the basal lamina via integrin α6β4.

Desmosome

Intercellular junction linking keratin intermediate filaments between adjacent cells.

Tonofilaments (Cytokeratins)

Keratin intermediate filaments providing tensile strength to epithelial cells.

Basal Lamina

Specialized ECM under epithelium; composed of lamina lucida and lamina densa.

Lamina Lucida

Clear zone of basal lamina directly beneath cell membrane; contains laminin.

Lamina Densa

Electron-dense portion of basal lamina rich in type IV collagen and proteoglycans.

Anchoring Fibril

Type VII collagen fibrils securing basal lamina to underlying connective tissue.

Collagen IV

Network-forming collagen predominant in lamina densa of basal lamina.

Collagen VII

Forms anchoring fibrils attaching basal lamina to dermal collagen.

Keratohyaline Granule

Basophilic granule in stratum granulosum containing filaggrin and other proteins.

Filaggrin

Protein that aggregates keratin filaments; key for cornified envelope formation.

Lamellar Body

Epidermal secretory organelle releasing lipids for water-barrier formation.

Bullous Pemphigoid

Autoimmune blistering disease targeting hemidesmosomal proteins BPAG1 & BPAG2.

BPAG1 (230 kDa)

Bullous pemphigoid antigen 1; intracellular plaque protein of hemidesmosomes.

BPAG2 (180 kDa)

Bullous pemphigoid antigen 2; transmembrane component linking to ECM.

Plectin

Cytolinker protein connecting keratin filaments to hemidesmosomal plaque.

Pemphigus Vulgaris

Autoimmune disease with antibodies against desmoglein-3 causing intraepidermal blisters.

Papillary Layer

Superficial dermal layer with loose CT, dermal papillae, and Meissner corpuscles.

Reticular Layer

Deep dermal layer of dense irregular CT containing thick collagen and elastic fibers.

Meissner Corpuscle

Tactile receptor in dermal papillae sensitive to light touch.

Pacinian Corpuscle

Onion-like mechanoreceptor in deep dermis/hypodermis sensitive to pressure and vibration.

Ruffini End Organ

Dermal mechanoreceptor responding to skin stretch.

Merkel Cell

Neural-crest–derived tactile cell in stratum basale forming Merkel disks.

Langerhans Cell

Antigen-presenting dendritic cell located in stratum spinosum.

Keratinocyte

Primary epidermal cell type producing keratin and forming the skin barrier.

Melanocyte

Pigment cell in stratum basale producing melanin transferred to keratinocytes.

Cutaneous Plexus

Deep vascular network at dermal-hypodermal junction supplying skin.

Subpapillary Plexus

Superficial vascular network below dermal papillae feeding capillary loops.

Arteriovenous Anastomosis

Shunt between arterioles and venules aiding thermoregulation in skin.

Hair Follicle

Invagination of epidermis producing hair shaft; associated with sebaceous glands.

Arrector Pili Muscle

Smooth muscle raising hair; inserts on hair follicle and papillary dermis.

Sebaceous Gland

Holocrine gland releasing sebum into hair follicle canal.

Internal Root Sheath

Inner epithelial layer of hair follicle surrounding growing hair.

External Root Sheath

Continuation of epidermis forming outer wall of hair follicle.

Cornified Cell Envelope

Protein-rich layer beneath plasma membrane of corneocytes strengthening barrier.

Lipid Envelope

Extracellular lipid layer from lamellar body secretion sealing stratum corneum.

Free Nerve Ending

Unmyelinated receptor in epidermis/dermis sensing pain and temperature.

Sweat Gland

Eccrine gland in dermis producing sweat for thermoregulation.