The Human Skin: The largest organ of the Integumentary System
The Human Skin
The human skin is considered as the largest organ of the integumentary system and one of the most important parts of the body. It is made up of several layers of epithelial tissues which guard the underlying muscles and organs of the body. The skin plays the most important role in terms of the protection through pathogens, sensation, insulation and regulation of body temperature . It also functions in the synthesis of Vitamin B and D.
The melanocytes provide the skin with pigmentation or melanin which absorbs the ultraviolet radiation in sunlight. Melanin also contains DNA repair enzymes which help in reversing the UV damage and skin cancer. Malignant melanoma is one effect of UV light which is considered invasive and deadly. Pigmentation varies among races thus leading to classification of people in terms of skin color.
The outer portion of the skin, the epidermis, is composed of stratified squamous epithelial tissue. Its outermost layer (stratum corneum) consists of hardened dead cells that are constantly being sloughed off. Active cell division in the deeper layers of the epidermis produces new cells that pushed outward and take the place of those that are lost. Beneath the epidermis is the dermis, a layer composed chiefly of connective tissue. Blood vessels penetrate into the dermis and not into the epidermis. Sweat glands are embedded in the deeper layers of the dermis, and their ducts push outward through both dermis and epidermis to open onto the surface through sweat pores. Both glands and ducts are derived from the epidermis; they form initially as folds of the epidermis that push downward into the connective tissue of the dermis.
Hairs, and the inner layer of the hair follicles in which they are encased, are also from the epidermis and also develop as folds into the dermis. When the hair follicle is fully developed, the bulbous base of the follicle and the hair root lie deep in the dermis; the shaft of the hair extends at a slant from the root to the surface of the skin and beyond. A small muscle runs diagonally in the upper portion of the dermis to the hair follicle near its lower end; when the muscle contracts, it pulls the hair erect. One or more sebaceous (oil) glands empty into the hair follicle. Numerous nerves penetrate into the dermis and few even penetrate into the epidermis. Among them are nerves o the hair muscle, sweat glands, and blood vessels, and also nerves terminating in the sensory structure for touch, temperature, and pain. Beneath the dermis, but not delimited from it, is a subcutaneous layer, which is not considered as the part of the skin itself. This is a layer of very loose connective tissue, usually with abundant fat cells. This is the layer that binds the skin from the body. The extent and form of its development determine the amount of possible skin movement.
Three Receptors of the Skin and the Senses They Mediate:
- FREE NERVE ENDING (pain). Some of the skin receptors are the unmyelinated terminal branches of neurons.
- NERVE PLEXUS AROUND THE HAIR (hair). Nets of nerve fibers surrounding the bases; these are stimulated by the slightest displacement of the tiny hairs present on most parts of the body.
- PACINIAN CORPUSCLE (deep pressure). Skin receptors have nerve endings surrounded by a specialized capsule of connective tissue cells.
The sensory receptors of the skin are concerned with touch, pressure, heat, cold, and pain. Unlike the receptors in the skin, which function in receiving information from the outside environment, some other receptors widely dispersed over the body function primarily in receiving information about the condition of the body itself.
The patterns of segments in living cells of the hair are being used as sources of genetic material to create the genetic fingerprint of an individual. Each one of us has our own unique genetic information or deoxyribonucleic acid (DNA) which can be separated and sorted into segments of different lengths. The resultant pattern looks like the bar code in the supermarket. Documented patterns are stored and used in identifying criminals, victims or for paternity test.
- Human Skin
Human Body Skin, parts, organs, systems, organ system, pictures, diagram, anatomy, muscles, bones, skeleton
- The Skin (Human Anatomy): Picture, Definition, Function, and Skin Conditions
WebMD's Skin Anatomy Page provides a detailed image of the skin and its parts as well as a medical definition. Learn about the skin's function and conditions that may affect the skin.
- Skin senses - human skin senses of pain, touch, cold and warm | the dynamic natural skin care