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List the functions of the integumentary system
- Protection
- Thermoregulation
- Defense
- Sensory perception
- Excretion
- Storage
- Vitamin production
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What are the cells that make up the epidermis?
- Keratinocytes
- Merkel Cells
- Melanocytes
- Langerhans cells
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What is the function of keratinocytes?
produce protein keratin
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List the five layers of the epidermis.
- Stratum basale (germinativum)
- Stratum spinosum
- Stratum granulosum
- Stratum lucidum
- Stratum corneum
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Describe the stratum basale
- deepest layer, relatively small
- single layer of cuboidal or columnar cells
- stem cells mitotically divide
- move to the surface in 2-4 weeks
- progressively die
- adheres to dermis
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Describe stratum spinosum
- 8-10 cells thick
- products of division in s. basale
- Extra-cellular fluid- lots of spaces between them
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Describe the cells of the epidermis and summary of their functions.
- The cells of the epidermis are:
- merkel cells- sensory perception location not at the top
- melanocytes- makes pigment
- keratinocytes- produce protein keratin (keratohylin);
- langerhan cells- immune system
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characteristics of keratinocytes
- compose most of the epidermis, as much as 70%
- produce protein keratin- a fibrous protein
- produced by rapid cell division of stems
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characteristics of merkel cells
- sensory perception
- associated with disc-shaped sensory nerve endings
- located at lowest layer of epidermis (between the layers of the epidermis and dermis)
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characteristic and function of melanocytes
- synthesize melatonin
- protection from UV light
- approximately constant in number- dark or light, pretty constant in number
- distribution varies
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characteristics and function of langerham cells
- wandering macrophages
- associated with immue system
- produced in red bone marrow
leave bone marrow, travel in red blood cells and leav, get into skin, when encountering foreign bodies, endocytosis (they eat them)
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layers of the epidermis
- stratum basale
- stratum spinosum
- stratum granulum
- stratum lucidum
- stratum corneum
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characteristics of stratum basale
- deepest layer (relatively small)
- single layer of cuboidal or columnar cells
- stem cells mitotically divide
- move to the surface in 2-4 weeks
- progressivly die
- adheres to dermis
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characteristics of stratum spinosum
- 8-10 cells thick
- products of division in s. basale
- extra-cellular fluid- lots of spaces between the cells
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characteristics of stratum granulosum
- keratinization (keratohyaline granules)
- melanin accumulation
- cell death
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characteristics of stratum lucidum
- found only in thick skin (elbow, palm, knees)
- cell layer appears clear
- cells begin to degenerate
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