I have been to two Body Worlds exhibits and one lesser-quality Chinese knockoff. If Body Worlds comes anywhere near to me in the future, I will go again. Some of my more squeamish friends have not been as enthusiastic as I am. Body Worlds displays some 200 or more real human (and occasionally animal) bodies that have been preserved by plastination for the purpose of teaching anatomy, physiology and health. According to Body World’s Educator’s Guide, “Plastination is a process that replaces the natural fluids in the body with a type of flexible plastic. The use of plastics for preservation means that the specimens are odourless and completely dry. Plastination allows the bodies to be fixed into life-like poses, illustrating how our bodies are structured and how they function when performing everyday activities.” The bodies are posed to accentuate various anatomical features. All are skinless.
The one pose that has stayed in my mind in vivid detail is the one of a man carrying his own skin (on page 9 of the link). [WARNING: Images of Body Worlds are graphic and may offend some people.] It would be a terrible pun (but that has never stopped me) to say that particular exhibit really got under my skin.
We could not live without our largest organ, the skin. Look down at the skin on your arms and hands. Count for 60 seconds. Did you see the shedding of approximately 30 to 40 thousand skin cells?
Like the other organs of the body, the skin is composed of tissues of various thicknesses and the tissues are composed of different kinds of cells. The visible layer of the skin–the epidermis–serves as a barrier without which our vulnerable inner tissues would be exposed to endless dangers. Because the outer skin layer takes a constant beating it is always being replaced. New skin is continually made in the bottom layer of the epidermis to replace the top layer. Additionally, the epidermis has pores to release toxins, shafts that contain hairs, and holds melanin creating the skin pigmentation necessary to shield against UV light produced by the sun. Between the first layer (epidermis) and third layer (hypodermis) that insulates us with its collagen and fatty deposits lies the very important and active middle area (dermis). It is the dermis where the blood vessels, lymph channels, the sensory receptors and nerve fibers are located. The cells of the epidermis receive their nourishment and waste disposal services from the underlying dermis. Tiny blood vessels (capillaries) carry nutrients to the skin. Any bacteria that has succeeded in passing through the epidermis must be captured and handled by the dermis.
Within the dermis tactile (somatosensory) receptors include:
- Free Nerve Endings that lie at the uppermost level of the dermis (occasionally reaching ever-so-slightly into the epidermis) and convey pain and temperature.
- Merkel cells, located on the fingertips at the junction of the dermis and the epidermis, having texture sensitivity and responding to slow vibrations and steady pressure. (Though their function is still not well understood, they are thought to have a neurosensory and multifunctional capacity in that they communicate with neurons).
- Ruffini’s corpuscle, a heat-gain sensitive tactile receptor present in large numbers in the dermis of the hairy regions; reacting especially to firm continuous pressure and high vibration.
- Bulb of Krause, a heat-loss sensitive tactile receptor.
- Meissner’s corpuscle, a tactile receptor located primarily at the level of the superficial dermis (just below the epidermis) of the hands, feet, lips and genital organs, sensitive to light touching and slow vibrations such as fluttering and stroking.
- Vater-Pacinian corpuscle, a deep pressure and high vibration sensitive receptor located deep in the dermis and even the hypodermis (and other visceral organs).
Uploaded to YouTube.com by photoprotection on Jun 8, 2010