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Lecture 4

PNB 2264 Lecture Notes - Lecture 4: Proteoglycan, Stratum Lucidum, Desquamation

Physiology and Neurobiology
Course Code
PNB 2264

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Notes day 4
PNB 2264
Integumentary system
- Skin
- Largest organ system in the body
- Covers tissues, organs and cells
- Major role is protection so what is the tissue type?
o The type that provides the greatest protection
What does it do?
- Protection
o Nails, hair, epithelium, waterproof
- Sensory
o Heat/cold, touch, pressure
- Thermoregulation
o Lose or gain heat, sweat
- Production of 7-dehydrocholesterol (UV light)
o Precursor to calcitriol (vitamin D)
What is it comsposed of?
- Epidermis (outer dermis)
o Variable width
0.1mm to 1mm
o Largest human organ
o Each square inch contails ~650 sweat glands, ~20 blood vessels, ~1000 nerve
endings, and ~60,000 melanocytes
o Five distinct layers
- Dermis (middle layer)
- Hypodermis (lower dermis)
- Avascular
o No blood vessels, will not bleed with damage
- Multiple layers
o Strata
- Stem cells
- Keratinocytes
o 95% of all cells, contains keratin
- sensory cells
- melanocytes
- basale (basal layer) stem cells
- spinosum (spiny layer) spiny shaped cells
- granulosum (granulated layer) granules
- lucidum (clear layer) clear, only found in palms and souls of feet
- corneum (hard layer) hard, tough, presence of desmosomes between cells
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