Skin Structure and Functions
UPACE, Open U ARTS4003BP
I Skin Structure
• Epidermis The epidermis is the outermost layer of the skin. It forms the protective covering of the skin of the body, It contains no blood vessels, but has many small nerve endings. The epidermis contains the following layers: Stratum Corneum, Stratum Lucidum, Stratum Granulosum , Stratum Spinosum and Stratum Germinativum. Dermis Dermis is the underlying, or inner layer of the skin, It is highly senSitive and vascular layer of connective tissue. Within it's structure are found numerous blood vessels, lymph, nerves, sweat gland, oil gland, hair follicles, arrector pilli muscles and papillae, The dermis consists of two layers: the papillary or superficial layer, and the reticular or deeper layer. Subcutaneous Fa~ Tissue (Hypodermis) Subcutaneous Tissue is a fattY layer found beow the dermiS. Some histologists consider this tissue as a continuation of the dermis.
• The stratum corneum: consists of tightly packed, scale-like cells, which are continually being shed and replaced. • The stratum lucidum: consists of small, transparent cells through which light can pass. It is only present on the palms of the hands and soles of the feet where the epidermis is the thickest. It is not present where there are hair follicles. 0
• The stratum granulosum: consists of cells that look like distinct granules. These cells are dying and undergo a change into a hard substance. • The stratum spinosum: is often classified with the stratum germinativum, to form the basal layer. As the cells undergo mitosis from below, they are pushed upward into the stratum spinosum . • The stratum germinativum: is composed of a singke layers of cells and is the lowest layer of cells that make up the living stratum or basal layer. It is in this layer that the cells divide and begin their journey to the surface , to replace older cells that are being shed. It is also the stratum germinativum layer that produces the pigment granules called melanocytes that give the skin its colors.
• Papillary Layer: lies directly beneath the epidermis. It contains small cone-shaped projections of elastic tissue that point upward into the epidermis. These projections are called papillae. Some of these papillae contain looped capillaries, other contain nerve fiber endings called tactile corpuscles which are nerve endings for the sense of touch.
• Reticular Layer contains the following structures within its network: a. Fat cells b. Blood vessels c. Lymph vessels d. Oil glands e. Sweat glands f. Hair follicles g. Arrector pili muscles
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• Subcutaneous tissue is a fatty layer found below the dermis. Some histologists consider this tissue as a continuation of the dermis. It varies in thickness according to the age, sex, and general health of the individual. It gives smoothness and contour to the body, contains fats for use as energy, and also acts as a protective cushion for the outer skin. Circulation is maintained by a network of arteries and lymphatics.
I How the skin is nourished?
• Blood and lymph supply nourishment to the skin. As they circulate through the skin, the blood and lymph contribute essential materials for growth, nourishment, and repair of the skin, hair, and nails. In the subcutaneous tissue are found networks of arteries and lymphatics that send their smaller branches to hair papillae, hair follicles, and skin glands.
I Skin elasticity
• The pliability of the skin depends on the elasticity of the dermis. Healthy skin regains its former shape almost immediately.
IAbsorption of the skin
• Natural openings in skin • Skin breathing • Shrinking Pores • Water • Skin color • Melanocytes
IAbsorption of the skin
-Natural openings in skin
• Although the skin is an intact outer layer of the...
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