Integument Flashcards
difference between thick and thin skin
stratum lucidum
Stratum basale
single cell layer of keratinocytes and some melanocytes; mitotically active; desmosomes and hemidesmosomes
Stratum spinosum
several cell layers thick; POLYHEDRAL keratinocytes with spiny processes; layer thickens with pressure (calluses)
Stratum granulosum
thickest non-keratinized layer of epidermis; keratinocytes here have keratohyalin granules; irregular shaped and variable in size
Keratohyalin granules
basophilic staining; cystine and histidine rich proteins; precursor to filaggrin, which helps assemble keratin into bundles
Stratum corneum
anucleated cells; filled almost entirely with mature keratin; plasma membrane coated with extracellular layer of lipids (water barrier); constantly shed these cells
Stratum lucidum
below corneum, above granulosum; poorly stained translucent bands of cells; no organelles or nuclei
predominant cell type of epidermis; produces keratins (85% of the cells); participate in epidermal water barrier
Keratinocytes
synthesizes intermediate keratin that is grouped into bundles known as tonofibrils
basal cells
keratin synthesis and the glycolipid lamellar bodies are being synthesized
spinous cells
discharge of lamellar bodies, keratohyalin granules present; filaggrin aggregates the tonofibrils; and the cells are now cornified
Granular cells
Neural crest derived and scattered along the stratum basale; make melanin and transfers it to keratinocytes
Melanocytes
one melanocyte maintains an association with a specific number of keratinocytes (1:36)
Epidermal-melanin unit
Oxidation of tyrosine (tyrosinase; UV sensitive)
DOPA
DOPA polymerized to
Melanin
where does melanin production occur
premelanosomes which become melanosomes and extend into cell processes, transfer to keratinocytes (phagocytosis)
pale cytoplasm with long processes; found in stratum spinous; APCs that migrate to a nearby lymph node to activate T cells
Langerhans Cells
epidermal cells that function in cutaneous sensation of the fingertips; exist in stratum basale
Merkel Cells
rare, highly aggressive skin cancer of Merkel cells
Merkel Cell Carcinoma (MCC)
Dermal-epidermal junction
uneven boundary except in thinnest skin; dermal papillae (finger-like) project into epidermis, and epidermal protrusions of epidermal (rate) ridges; increase in size due to mechanical stress
loose CT below epidermis; thin collagen fibers and elastic fibers; includes dermal papilla and ridges; VASCULATURE and NERVES
Papillary layer of dermis
Deep to papillary layer; thicker and less cellular; irregular bundles of type I collagen and coarse elastic fibers; Langer’s lines
Reticular layer of dermis
Langer’s lines
regular lines of tension
adipose tissue, varies in thickness, every storage, arrestor pili muscles (for hair);
Hypodermis (subcutaneous fascia) not technically integument
