Skin
HypodermisSkin Color
Skin Function
Subcutaneousor Hypodermis
• Not part of the skin
•Between dermis and tissues below
• Rich in Adipose tissue (subcutaneous fat)•Subcutaneous injections
Skin Color
• Determined by amount of1. Melanin2. Carotene3. Hemoglobin at surface
1. Melanin
• Dark Brown pigment
• Produced by Melanocytes– Stratum Basale– Tyrosine → Melanin
• Enzyme Tyrosinase
Melanin
• Decreased Tyrosinase– Graying of Hair– White skin of elderly
Melanin
• Absence of Tyrosinase– Albinism (recessive)
Melanin
• Absence of Tyrosinase– Albinism
Melanin
• Melanocytes can group together– Results in ….
Melanin
• Freckles
Amount of Melanin
• Controlled by– Genes
– Environment• UV radiation
2. Carotene
• Yellow-orange pigment
• Found in food products
3. Hemoglobin
• Red Tint
– Vessels dilate at surface- Embarrassment (nerves)
Skin Functions
1. Protection– Microorganism barrier
– Water loss (keratin)
– Chemicals (keratin)
Skin Functions
– Physical damage (collagen fibers and desmosomes)
– UV damage (melanin)
Skin Functions
2. Sensory– Pressure, touch, pain, and
temperature
Skin Functions
3. Excretion– Salts and wastes (urea)
Skin Functions
4. Vitamin D production– UV light reaction– Important for calcium
absorption in bones
Skin Functions
5. Immunity– Macrophages in tissue
Skin Functions
6. Temperature regulation– Release Heat
• Vasodilatation – Increase blood flow to dermis
Skin Functions
6. Temperature regulation– Conserve Heat
• Vasoconstriction – Decrease blood flow to dermis