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Structure and Function of The Skin

»	Name the three layers of the skin. What composes them?
»	How many layers are there in the epidermis? How are they organized?
»	Do other types of cells normally occur in the epidermis?
»	What is apocopation?
»	Describe the structure of the basement membrane zone (BMZ).
»	How is the structure of the epidermis related to its functions?
»	What structural components of the epidermis are involved in blistering diseases?
»	Are there hereditary diseases of the BMZ and dermis that cause blistering and damage to the skin?
»	Are there acquired blistering diseases of the BMZ and dermis?
»	What abnormalities in structural components of the basement membrane are involved in bullous skin diseases?
»	What is the function of the sebaceous gland?
»	How do the eccrine sweat glands and apocrine sweat glands differ?
»	How is the dermis organized?
»	What are the components of the dermis?
»	What are the functions of the dermis?
»	Which structural component of the dermis is involved in congenital and autoimmune skin diseases?
»	How does the vasculature of the dermis function in temperature control?
»	How is the skin innervated?
»	Name the two main corpuscular (encapsulated) nerve receptors found in the skin.
»	Is loss of cutaneous sensation very serious?
»	How is the subcutis organized?

What are the components of the dermis?

The main cell type in the dermis is the fibroblast. The fibroblast produces the main components of the dermis, including collagen (70% to 80%) for resiliency, elastin (1% to 3%) for elasticity, and proteoglycans to maintain water within the dermis. The bulk of the collagen within the dermis consists of types I and III and is organized into collagen bundles that mostly run horizontally throughout the dermis. The elastic fibers are interspersed among the collagen fibers. Oxytalan fibers are small elastic fibers found primarily in the papillary dermis and are usually oriented perpendicularly to the skin surface. The proteoglycans (primarily hyaluronic acid) comprise the amorphous ground substance around the elastic and collagen fibers.