The Skin

Abstract

The concepts and techniques of mathematics, physics, and engineering are being applied as never before to biology and medicine. This is evidenced by rapidly developing hybrid disciplines such as biomathematics, biophysics, bioengineering, biomechanics, and bioclimatology. The opportunities for such interdisciplinary collaboration are far more extensive than is generally recognized. We have selected the skin as an example to show the diversity of biological problems which can be approached collaboratively by investigators with widely different backgrounds.The skin is an appropriate choice for many reasons. Everyone is familiar with many of its characteristics. Samples are immediately at hand for direct examination or quantitative measurements. It has both living and nonliving components susceptible to physical and chemical measurements. It contains many different tissues, including blood vessels, glands, sense organs and nerves, smooth muscle, connective tissue, and fat. Although many of its properties have been examined in the past, much remains to be learned. For example, diseases and lesions of the skin are generally identified primarily on the basis of their appearance. Comprehensive descriptions of the biological, physical, and chemical properties of the skin are badly needed to clarify its function in health and to serve as criteria for determining the presence of disease. OCTOBER 1966Human skin is a highly specialized organ with remarkable properties and diverse functions. Many primitive organisms live in a watery environment which ordinarily protects them against rapid fluctuations in temperature, humidity, concentration gradients, acceleration, toxic chemicals, radiation, and so forth. If their immediate environment suddenly changes, they die for lack of compensatory mechanisms. When living forms emerged from primordial swamps, their external skin became specialized as a barrier between delicate living cells and a capricious, often unfriendly environment. In the most highly developed organisms, the body cells flourish within a thermostatically controlled culture medium resembling in many respects an ancient tropical sea. With the skin as an effective barrier, the immediate environment of cells remains remarkably undisturbed during wide fluctuations in environmental conditions. Human tolerance to environmental changes evokes interest among many types of investigators, including anatomists, physiologists, dermatologists, and surgeons, and extends into areas of physics, chemistry, various fields of engineering, and far beyond.This article is intended to direct the attention of quantitative scientists to the opportunities for effective collaboration on problems related to biological structures and organisms.

Neurophysiology of Skin Thermal Sensations

“…As opposed to hairy skin, glabrous skin presents a thicker stratum corneum (i.e. outermost skin layer), a fact which translates in a greater thermal insulation and in a potentially lower thermal conductance of this type of skin as compared to the rest of the body (256). This lower thermal conductance could result in prolonging the time needed for a given change in the temperature of the superficial layers of glabrous skin to penetrate to the underlying tissues (e.g.…”

An elastic second skin

“…This loss of elastic recoil is not reversible by existing therapies 8 and consequently remains the universal fate of our largest and most visible organ 9 . Recent progress in materials science and engineering have yielded flexible skin interfacing technologies 10,11,12 that are functionalized in some cases for pharmaceutical delivery 13 , rapid analyte detection 14 , continuous physiological monitoring of medical conditions 15 , and wound healing 16,17,18 .…”

Soft Tissue Modelling from 3D Scanned Data

“…The physieal properties of the human skin and fat are very weIl known [Da82], [La87]. For example, regional differenees of skin thiekness have been extensively studied [Ru66], [H074]: the two first layers of human skin (dermis and epidermis) varies in thickness from O.5mm on eyehds to more than 5mm on the middle of the upper back.…”

“…We duplieate the surfaee mesh to generate the three layer volumetrie mesh (see Figure 5). The thieknesses of the epidermis, dermis and subeutaneous fat are set respeetively, using average values, at O.2mm, 2mm [Ru66] [Ho74] and 8.9mm [Fr81].…”