Integumentary System 1 Flashcards
Which layer of skin is CT layers derived from mesoderm?
Dermis
Which layer of skin is keratinizing stratified squamous epithelium derived from ectoderm?
Epidermis
What type of cell transforms into protective flat scales of keratin?
Keratinocytes
What cells are derived from lympoid progenitor cells, enter the epidermis, where they phagocytize and process antigens entering through the skin?
Langerhan’s cells
What type of cells produce melanin?
Melanocytes
What cells are associated with sensory nerve endings?
Merkel’s cells
Epidermis consists of several layers of keratinocytes that represent stages of a specialized form of apoptosis. Cells continously grow maintaining a consistent thickness of skin. Proliferation is driven mainly by what, which is locally produced by dermal fibroblasts in response to what hormone?
IGF, GH
Skin cells eventually undergo apoptosis by what two mechanisms?
DNA fragmentation, being filled with keratin
Which layer of skin is a simple layer of stem cells that differentiate into keratinocytes?
Stratum basale
Which layer of skin is a stratified layer of cells that enlarge and form processes and flatten as they progress toward the surface?
Stratum spinosum
Which layer of skin is made of cells that develop granules with precursors of filaggrin, a protein that aggregates keratin filaments?
Stratum granulosum
Which layer of skin consist of cells that flatten, lose their nuclei and organelles and become filled with keratin filaments?
Stratum corneum and lucidum
Keratinocytes in the basal layer proliferate and synthesize keratin proteins, as they enter what layer?
Stratum spinosum
In what layer does keratin granules form and release filaggrin and trichohyalin into the cytoplasm?
Stratum granulosum
What is the effect of filaggrin aggregating keratin into bundles of intermediate filaments called tonofibrils?
Flattens and cornifies the cell with soft keratin
What are the four most prominent functions of keratin and its various forms of intermediate filaments.
Mechanical support - to strengthen and maintain integrity of epidermis
Cytoarchitectural functions - i.e. regulate desmosomal attachment to other cells, cell migration
Organelle/vesicle distribution - especially transport of melanin-filled melanosomes
Regulation of signaling pathways affecting apoptosis - oxidative stress responses and protein synthesis
Desquamation (exfoliation) of cells depends on what?
pH gradient
All nucleated cells are linked by what, which imparts physical strength to the epidermis?
Desmosomes
What exfoliates the cells by breaking down the desmosomes, in a pH dependent manner?
Peptidases
In the deeper epidermal layers where pH in neutral what prevents peptidase actions on desmosomes and inhibits exfoliation?
Protease inhibitors, LETKI
As pH drops in the superficial layers (epidermis), what is permitted to release keratinocytes?
KLK - kallikrein related serine peptidases
