STRUCTURE OF EPIDERMIS Flashcards
What is the stratum corneum?
Protects skin from stuff going in and out
What is stratum germinativum?
Basal layer of epidermis
Structure of EPIDERMIS from superficial to deepest (7):
- Stratum corneum
- Stratum lucidum (clear layer)
- Stratum granulosum
- Stratum spinosum
- Stratum germinativum
- Dermal papilla
- Dermis
What is stratum germinativum known as?
Stratum basale
What is stratum germinativum composed of?
Large basal cells
Where do stratum germinativum attach to?
Firmly attach to basal lamina
What are the large basal cells in stratum germinativum?
Stem cells that divide to give rise to new keratinocytes
What are keratinocytes?
Most abundant epithelial cells in epidermis
What is the stratum spinosum known as?
Spiny layer
What is stratum spinosum composed of?
Keratinocytes
What do keratinocytes contain?
Contain bundle of tonofilaments (protein filaments)
What are tonofilaments?
Act as cross braces; begin and end between adjacent cell junctions (desmosomes)
What do desmosomes do?
Attach keratinocytes together
What are keratinocytes still capable of?
Division
What is the stratum granulosum known as?
Granular layer
What does the stratum granulosum produce?
Production of large quantities of keratohyalin and keratin
What does the accumulation of keratohyalin lead to?
Keratohyalin granules
What is the function of granules?
Secrete lipids that fill spaces between keratinocytes (form water-repellent sealant)
What does the sealant prevent and eventually lead to?
Prevent cell diffusion, leading to keratinocyte death
What is the stratum lucidum known as?
Clear layer
What is stratum lucidum composed of?
Large amounts of keratin and thickened plasma membrane
Where is stratum lucidum only found?
Only found in volar skin (palmar and plantar skin)
What is stratum corneum known as?
Corne (hoof-like or hard)
What is stratum corneum composed of?
Multiple layers of dead cells
