SM_255a: Structure and Function of Skin Flashcards
Skin functions include ____, ____, ____, ____, ____, and ____
Skin functions include barrier, repair, immunologic, sensation, thermoregulation, and appearance
- Barrier: resist mechanical stress, limit water loss from inside, block entry from outside, UV shield
- Repair: wound healing
- Immunologic: temper and alert immune system
- Sensation: pain, itch, pressure
- Thermoregulation, insulation, and absurption
- Appearance: quality of life
Skin layers from outermost to innermost are ____, ____, and ____ and appendages include ____, ____, ____, and ____
Skin layers from outermost to innermost are epidermis, dermis, and hypodermis and appendages include hair, sebaceous glands, sweat glands, and nails
Epidermis is ____
Epidermis is keratinizing stratified squamous epithelium
Dermis is ____
Dermis is connective tissue/stroma
Dermis includes the ____ and ____
Dermis includes the outer papillary dermis and inner reticular dermis
Epidermis is ____, while the dermis ____
Epidermis is avascular, while the dermis is vascular
Describe the layers of the epidermis from bottom up
Layers of the epidermis from bottom up
- Basal layer (stratum basale): proliferation/anchorage - E-cadherin
- Spinous layer (stratum spinosum): adhesion - demososomes
- Granular layer (stratum granulosum): differentiation
- Cornified layer (stratum corneum): death
Epidermal cell layers are ____
Epidermal cell layers are morphologically distinct
____ are the major cell type in the epidermis
Keratinocytes are the major cell type in the epidermis
(keratinocytes exist in various states of proliferation and differentiation in epidermis)
In addition to keratinocytes, ____, ____, and ____ are found in the epidermis
In addition to keratinocytes, Langerhans cells, melanocytes, and Merkel cells are found in the epidermis
- Langerhans cells: dendritic antigen presenting cells
- Melanocyte: pigment-producing cells
- Merkel cells: mechanoreceptor
Epidermis functions primarily to build a ____ in order to ____, ____, ____, and ____
Epidermis functions primarily to build a semi-permeable barrier in order to resist physical trauma and repair wounds, prevent entry of noxious agents (outside-in barrier), limit excessive water loss (inside-out barrier), and protect against UV irradiation from sun
Epidermis building involves replenishing to ____
Epidermis building involves replenishing to maintain a constant supply of keratinocytes to repopulate upper layers
- Stem cells in the basal layer give rise to proliferating compartment
- Basal layer cells exit cell cycle and replenish upper layer
- Outermost cells are constantly sloughed off
- Epidermis turns over every 30 days
Psoriasis is an ____ skin disease that involves ____, ____, and ____
Psoriasis is an inflammatory skin disease that involves increased keratinocyte proliferation and turnover, abnormal differentiation, and formation of thick scaly plaques
Epidermis building involves resisting which is accomplished by ____
Epidermis building involves resisting which is accomplished by specialized structures to yield a strong cell
- Keratinocytes maintain shape by building cytoskeleton networks: microtubules, actin-based microfilaments, keratin-based intermediate filaments
- 54 different human keratins pair up to form intermediate filaments
- Keratins are major protein in keratinocytes
- Keratin composition changes as keratinocytes differentiate
____ are responsible for maintaining shape of the epidermis by building cytoskeleton networks
Keratinocytes are responsible for maintaining shape of the epidermis by building cytoskeleton networks
Keratins ___ and ___ are expressed in the basal layer, while keratins ___ and ___ are expressed in the spinous and granular layers
Keratins 5 and 14 are expressed in the basal layer, while keratins 1 and 10 are expressed in the spinous and granular layers
____ occurs due to issues with keratin 5 and 14 in the basal layer
Epidermolysis bullosa simplex occurs due to issues with keratin 5 and 14 in the basal layer
____ occurs due to issues with keratin 1 and 10 in the spinous and granular layers
Epidermolytic ichthyosis occurs due to issues with keratin 1 and 10 in the spinous and granular layers
____ anchored to the ____ attach the epidermis to the underlying dermis
Keratinocytes anchored to the underlying dermis attach the epidermis to the underlying dermis
____ are integrin-based junctions that connect basal keratinocytes to the basement membrane
Hemidesmosomes are integrin-based junctions that connect basal keratinocytes to the basement membrane
____ occurs due to mutations in hemidesmosome gene COL17A1
Junctional epidermolysis bullosa occurs due to mutations in hemidesmosome gene COL17A1
____ occurs due to autoantibodies against collagen 17, which ____
Bullous pemphigoid occurs due to autoantibodies against collagen 17, which breaks the connection between basal keratinocytes and basement membrane
____ are specialized junctions that anchor keratin to sites of cell-cell contact
Desmosomes are specialized junctions that anchor keratin to sites of cell-cell contact
____ occurs when autoantibodies target proteins found in desmosomes, ____
Pemphigus vulgaris occurs when autoantibodies target proteins found in desmosomes, breaking the connection between adjacent keratinocytes
