Download - Skin - Biology
![Page 1: Skin - Biology](https://reader034.vdocument.in/reader034/viewer/2022052619/556de00bd8b42a524e8b49d2/html5/thumbnails/1.jpg)
![Page 2: Skin - Biology](https://reader034.vdocument.in/reader034/viewer/2022052619/556de00bd8b42a524e8b49d2/html5/thumbnails/2.jpg)
General Facts:
A.First line of defense
B.Vital to homeostasis
C.Largest body organ
![Page 3: Skin - Biology](https://reader034.vdocument.in/reader034/viewer/2022052619/556de00bd8b42a524e8b49d2/html5/thumbnails/3.jpg)
Functions of the skin:
1. Protection
2. Regulate body temperature
3. Decrease water loss
4. Contains sensory receptors
5. Synthesize biochemicals
6. Excrete waste
![Page 4: Skin - Biology](https://reader034.vdocument.in/reader034/viewer/2022052619/556de00bd8b42a524e8b49d2/html5/thumbnails/4.jpg)
Regions
Epidermis – outermost layer
Dermis – middle layer
Subcutaneous– deepest layer
![Page 5: Skin - Biology](https://reader034.vdocument.in/reader034/viewer/2022052619/556de00bd8b42a524e8b49d2/html5/thumbnails/5.jpg)
Epidermis
• Composed of cells in four or five layers
• Lacks blood vessels
• Outer portion of the skin that is exposed to the external environment and functions in protection
![Page 6: Skin - Biology](https://reader034.vdocument.in/reader034/viewer/2022052619/556de00bd8b42a524e8b49d2/html5/thumbnails/6.jpg)
![Page 7: Skin - Biology](https://reader034.vdocument.in/reader034/viewer/2022052619/556de00bd8b42a524e8b49d2/html5/thumbnails/7.jpg)
Cells of the Epidermis
• Most cells in the epidermis produce the fibrous protein keratin
• Some cells produce the brown pigment melanin
• Some cells turn on the immune system
• Some cells function as touch receptors in association with sensory nerve endings
![Page 8: Skin - Biology](https://reader034.vdocument.in/reader034/viewer/2022052619/556de00bd8b42a524e8b49d2/html5/thumbnails/8.jpg)
Skin ColorThree pigments contribute to skin color•Melanin – yellow to reddish-brown to black pigment, responsible for dark skin colors•Carotene – yellow to orange pigment, most obvious in the palms and soles of the feet•Hemoglobin – reddish pigment responsible for the pinkish hue of the skin
Sunlight causes the melanin production to increase.
Circulation with dermal blood vessels affects skin color.
![Page 9: Skin - Biology](https://reader034.vdocument.in/reader034/viewer/2022052619/556de00bd8b42a524e8b49d2/html5/thumbnails/9.jpg)
Dermis
• Second major skin region containing strong, flexible connective tissue (collagen fibers) and blood vessels that carry nutrients to upper layers of skin and help regulate body temperature
![Page 10: Skin - Biology](https://reader034.vdocument.in/reader034/viewer/2022052619/556de00bd8b42a524e8b49d2/html5/thumbnails/10.jpg)
Also consists of nerves, hair follicles, sweat glands, oil glands and muscles.
![Page 11: Skin - Biology](https://reader034.vdocument.in/reader034/viewer/2022052619/556de00bd8b42a524e8b49d2/html5/thumbnails/11.jpg)
Subcutaneous (Hypodermis)
• Deepest layer of the skin
• Composed of a fatty layer and loose connective tissue
• It binds the skin to underlying organs and contains the blood vessels that supply the skin.
• There is no sharp boundary between the dermis and the hypodermis
![Page 12: Skin - Biology](https://reader034.vdocument.in/reader034/viewer/2022052619/556de00bd8b42a524e8b49d2/html5/thumbnails/12.jpg)