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