Skin anatomy

FIGURE 94-1. Skin anatomy Breslow microstaging and Clark levels. (Reprinted from Langley RGB, Barnhill RL, Mihm Jr MC, et al. Neoplasms Cutaneous melanoma. In Freedberg IM, Eisen AZ, Wolff K, et al, (eds.) Fitzpatrick s Dermatology in General Medicine. 6th ed. New York McGraw-Hill 2003 938.)... 

The skin is a complex multilayered tissue with a large surface area exposed to the environment. Skin anatomy, physiology, and biochemistry vary among species, within species, and even between anatomic sites within an individual animal or human. Logically these biological factors alone can influence dermal absorption. What is consistent is that the outer layer, the stratum corneum (SC), can provide as much as 80% of the resistance to absorption to most ions as well as aqueous solutions. However, the skin is permeable to many toxicants, and dermal exposure to agricultural pesticides and industrial solvent can result in severe systemic toxicity. 

PNLM 1. Administration, Cutaneous. 2. Skin—metabolism. 3. Skin— anatomy histology. W1 DR893B v.83 1997 / WB 340 M486 1997]... 

As can be appreciated from this overview of the structure and function of skin, it is important to understand the basic aspects of skin anatomy and physiology to interpret the effects of exposure to occupational chemicals (solvents, corrosives, or... 

Wysocki, A., 1999. Skin anatomy, physiology, and pathophysiology. Nurs. Clin. N. Am. 34, 777-799. 

Boyce, S.T., Greenhalgh, D.G., Kagan,R.J.,Housinger,T, Sorrell, J.M., Childress,C.P.,Rieman, M., and Warden, G.D., Skin anatomy and antigen expression after burn wound closure with composite grafts of cultured skin cells and biopolymers, Plast. Reconstr. Surg., 91,632, 1993. 

There are many skin substitute technologies that are either available clinically or undergoing some stage of preclinical tests. Quite often, to develop those products that are clinically used today, scientists obtain inspiration from many interesting aspects of skin anatomy, immunology, and physiology (Rowan et al., 2015 Varkey et al., 2015 Yellowlees, 1990). 

A. Durward, The skin and the sensory organs, in Cunningham s Testbook of Anatomy (G. J. Romanes, ed.), Oxford University Press, London, 1964, p. 796. 

Teat skin, teat canal Contamination Environment, udder anatomy, milking machine... 

Cardiovascular anatomy and physiology Ventricular performance Electrophysiology Coronary artery distribution Human skin... 

Species differences in absorption may occur for any of the following reasons differences in gastrointestinal pH or anatomy, differences in rate of blood flow to the absorption site, differences in breathing rate, differences in skin type, and the presence or absence of fur. 

The female mosquito s blood sampling ability has often been cited as an inspiration for development of microneedle-based systems. A few features of the mosquito anatomy and extraction ability are noteworthy. The mosquito s labium is about 3.5 mm long and narrows to an inner diameter of about 30 pm. The labium is applied to the skin with a hammer-like motion at the rate of 6-7 Hz for penetration. A muscle valve and mouth pump move in concert to create about 7 kPa of negative pressure that is sufficient to extract 1.9 pL of blood in 2 min.54 There is some indication that the mosquito can sense when a source of blood is reached and can change the direction of insertion while partway in the skin to achieve a greater rate of success. While the mosquito has served as inspiration for design and function parameters, man-made devices to date have relatively rudimentary functionality in comparison. 

The anatomy of the tuber is shown diagrammatically in Figure 11.2. Parts that can be distinguished are the skin (periderm) with the lenticels, the eyes, the bud and stem ends, the cortex, the ring of vascular bundles, the perimedullary zone, and the pith with medullary rays which are homologous with the medulla of the stolon.7... 

In order to have a basic understanding and appreciation of how chemicals may interact with skin, its anatomy, physiology, and chemical composition must be fully grasped. All of the aforementioned biological functions and structural adaptations have a substantial impact on the skin s barrier properties and the rate and extent of percutaneous absorption. When a compound or toxicant is applied topically, it must penetrate through several cell layers of the skin in order to be absorbed by the capillaries for systemic distribution. Alternatively, it may have a direct effect on the keratinocytes themselves. Skin can be anatomically divided into two principal components, the outermost epidermis and the underlying dermis. 

Monteiro-Riviere, N. A. Comparative anatomy, physiology, and biochemistry of mammalian skin. In Hobson, D. W. (Eds.). Dermal and Ocular Toxicology Fundamentals and Methods, CRC Press, New York, 1991, Chapter 1, pp. 3-71. 

EXHIBIT A Anatomical and Physiological Considerations Unique to Children. differences in anatomy. allometric scaling factors (e.g. increased surface area-to-volume ratio) cardiovascular status permeability of the pediatric blood-brain barrier (BBB). dermatologic factors (e.g. increased cutaneous blood flow) (Fluhr et al., 2000 Simonen et al, 1997). increased skin pH (Fluhr et al., 2004 Behrendt and Green, 1958) plasma protein binding volume of distribution (V ) organ size and maturity pharmacokinetic maturity (e.g. metabolic differences) (Fairley and Rasmussen, 1983)... 

Before the discussion of transdermal transport, it is essential to understand the anatomy and barrier properties of skin. Briefly, the skin can be viewed as two main layers the epidermis and the dermis. The thickness of epidermis varies from approximately 0.07 to 0.12mm (except on the palms and the soles), and is composed of the stratum corneum, stratum lucidum, stratum... 

Montagna, W. Comparative anatomy and physiology of the skin. Arch. Dermatol. 1967, 96, 357-363. 

If acupuncture, which entails tissue trauma, is performed properly and on the correct acupuncture points, trauma will affect only the skin and the connective tissue below. If, however, acupuncture needles are inserted at the wrong site or penetrate too deeply, other tissues or organs can be affected. Traumatic complications of acupuncture have been reviewed (108). They have been described in relation to the thoracic and abdominal viscera, in the peripheral and central nervous systems, and in blood vessels. Several deaths have been reported from pneumothorax and cardiac tamponade. The anatomical tissues at several acupuncture points are such that needles can injure vulnerable structures. Thus, good knowledge of anatomy is an essential precondition for acupuncturists. 

FIGURE 2.37 Thoracic duct and other vessels of the thorax. Lymphatic capillaries are most numerous just beneath body surfaces, such as the skin and the mucus membranes of the gastrointestinal and respiratory tracts. The mucus membrane of the gastrointestinal tract is called the gut mucosa. The general function of these capillaries is to absorb interstitial fluid that has leaked from the circulatory system and to return it to the bloodstream. The function of the l)miphatic capillaries that end in the lacteals of the small intestine is to transport absorbed dietary lipids. These capillaries coalesce and eventually deliver their contents to the thoracic duct. The lymph collected from other parts of the body, as indicated by the "collecting trunk," also is transferred to the thoracic duct. [Redrawn with permission, from "Grant s Atlas of Anatomy," Williams Wilkins Co., Baltimore, 1978.]... 

Fig. 5.1 Anatomy and physiology of the skin, showing the potential targets or site of action for cosmetics and drugs...

Formaldehyde-specific IgE was not detected in a group of 45 medical students, before or after the students attended a 4-week anatomy dissecting course (Wantke et al. 1996b). Estimates of laboratory air concentrations of formaldehyde ranged from 0.059 to 0.219 ppm (mean 0.124 0.05 ppm). Surveys revealed frequencies of irritation symptoms consistent with other studies (e.g., itching of the skin in 33/45 students, headache in 15/45, and burning eyes in 13/45). 

Medical devices can be anything from thermometers to artificial hearts to in-home pregnancy test kits. Devices, unlike drugs, are not dependent on a chemical action. Device inventors are more concerned with anatomy—skin, internal organs, tissue—and the compatibility of the device both within and on the surface of the body. 

A primary factor to consider in evaluation is the age of the patient. Changes in the anatomy and physiology of skin and its appendages relate closely to patient age, and for women hormonal status also affects the evaluation. 

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