Chapter 11 - Skin
Skin covers the outer surface of the body and is the largest organ. Skin and it's accessory structures (hair, sweat glands, sebaceous glands, and nails) make up the integumentary system. Its primary functions are to protect the body from the environment and prevent water loss.
Skin is classified into two types:
- Thick skin - covers the palms of the hands and the soles of the feet
- Thin skin - covers the rest of the body
Thin Skin
Thin skin covers most of the body except for the palms of the hands and the soles of the feet. It has a relatively thin epidermis and contains hair follicles, sweat glands, and sebaceous glands.
Keratinocytes are firmly attached to each other by desmosomes, which makes the skin strong and flexible.
The epidermis is firmly attached to the supportive connective tissue by many hemidesosomes to the underlying basal lamina.
Pigmented Skin
Melanin is the most important substance in determining the color of skin.
Langerhans Cells
Langerhans cells are immune sentinels of the skin. These antigen-presenting cells prime lymphocytes ultimately leading to a broad range of immune responses.
Hair
Hairs protrude from structures known as hair follicles.
