The skin is the largest organ of the body. The skin protects us from microbes and the elements,
sunlight and helps regulate body temperature, and permits the sensations of touch, heat and cold.
Our skin has three layers:
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The epidermis, the outermost layer of skin, provides a waterproof barrier and creates our
skin tone.
The dermis, beneath the epidermis, contains tough connective tissue, hair follicles and sweat
glands.
The deeper subcutaneous tissue (hypodermis) is made of fat and connective tissue.
The skin’s color is created by cells called melanocytes, which produce the pigment melanin.
Melanocytes are located in the epidermis.
Epidermis
This epidermis can be further subdivided into
? Stratum corneum
? Stratum granulosum
? Stratum lucidum (only in palms and soles)
? Stratum spinosum
? Stratum basale
Dermis
Papillary region: The papillary region is composed of loose areolar connective tissue. This is
named for its fingerlike projections called papillae that extend toward the epidermis. The papillae
provide the dermis with a "bumpy" surface that interdigitates with the epidermis, strengthening the
connection between the two layers of skin.
Reticular region: The reticular region lies deep in the papillary region and is usually much
thicker. It is composed of dense irregular connective tissue, and receives its name from the dense
concentration of collagenous, elastic, and reticular fibres that weave throughout it.
These protein fibres give the dermis its properties of strength, extensibility, and elasticity. Also
located within the reticular region are the roots of the hair, sebaceous glands, sweat
glands, receptors, nails, and blood vessels.
Hypodermis
Lies below the dermis. Its purpose is to attach the skin to underlying bone and muscle as well as
supplying it with blood vessels and nerves. It consists of loose connective tissue and elastin. The
main cell types are fibroblasts, macrophages and adipocytes (the hypodermis contains 50% of body
fat). Fat serves as padding and insulation for the body. Another name for the hypodermis is
the subcutaneous tissue.
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