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General Thermography
Published in James Stewart Campbell, M. Nathaniel Mead, Human Medical Thermography, 2023
James Stewart Campbell, M. Nathaniel Mead
Sunburn involves a different damage mechanism, quite distinct from thermal burns. Thermal burns are caused by excess infrared (IR) exposure, which can penetrate deeply by conduction. Sunburn is caused by excess ultraviolet (UV) exposure, which does not penetrate the skin deeply or create much heat. UV exposure damages dermal cellular organelles and DNA, causing inflammation. Strong ultraviolet sources other than sunlight can also cause skin damage. Overexposure to a welding arc results in a type of UV burn that appears similar to sunburn, though the distribution over the skin is different. Like welder's burns, overexposure to UV reflecting off snow causes corneal photokeratitis (“snow blindness”) and can damage anatomy not usually affected by sunburn, such as the roof of the mouth or the interior of the nostrils.11
Biological Effects of Millimeter and Submillimeter Waves
Published in Ben Greenebaum, Frank Barnes, Biological and Medical Aspects of Electromagnetic Fields, 2018
Stanislav I. Alekseev, Marvin C. Ziskin
The human skin consists of three individual layers: the epidermis, dermis, and hypodermis. The epidermis, the outermost layer of skin, is about 0.1 mm thick but on the palms of the hands it can be 0.7 mm thick or more (Bloom and Fawcett, 1968; Odland, 1971; El Gammal et al., 1999; Welzel et al., 2004). The majority of cells in the epidermis are keratinocytes. The surface layer of the epidermis is called the SC. The SC is made up of flattened dead keratinocytes, which have lost their internal structure. The thickness of the SC in the forearm skin is about 0.012–0.018 mm (Kligman, 1964; Rajadhyaksha et al., 1999; Huzaira et al., 2001; Caspers et al., 2003; Sandby-Moller et al., 2003). The rest of the epidermis (without the SC) consisting of live cells is called the viable epidermis. The dermis is organized into a papillary (outer) and a reticular (inner) region. The distinction between the two layers is based mostly on their differences in connective tissue. Literature data of the dermis thickness depend on location and on the methods used for thickness measurements, and vary from 1.0 to 2.0 mm (Meema et al., 1964; Black, 1969; Shuster et al., 1975; Dykes and Marks, 1977; Fornage and Deshayes, 1986; Branchet et al., 1990; Gniadecka and Quistorff, 1996). The hypodermis is composed mainly of fat cells and connects the dermis to underlying tissues and muscle.
Modelling and analysis of skin pigmentation
Published in Ahmad Fadzil Mohamad Hani, Dileep Kumar, Optical Imaging for Biomedical and Clinical Applications, 2017
Ahmad Fadzil Mohamad Hani, Hermawan Nugroho, Norashikin Shamsudin, Suraiya H. Hussein
The dermis is the second primary layer of skin beneath the epidermis. It is connected to the epidermis by a basement membrane. Contingent upon the area of the body, dermis is roughly 1−4 mm thick and made out of flexible collagen fibres, veins, nerves, lymph vessels, hair follicles and sweat glands. The dermis contains a lot of arteries and veins as well as capillaries for blood circulation. Here, blood carries pigment haemoglobin, which acts as the main absorber of light in dermis [38]. The microvasculature are concentrated on the uppermost layer of the dermis, called papillary plexus and the larger vessels are situated on a lower layer, called cutaneous plexus [45]. A layer between the papillary plexus and cutaneous plexus may contain fewer blood vessels (Figure 4.6).
Recapitulate genistein for topical applications including nanotechnology delivery
Published in Inorganic and Nano-Metal Chemistry, 2022
Afroz Jahan, Juber Akhtar, Neha Jaiswal, Asad Ali, Usama Ahmad
As estrogen levels drop during menopause, testosterone stimulates sebaceous glands to produce thicker sebum, resulting in oily skin; moreover, some women may develop facial hair, primarily on the chin. Estrogen levels decrease when fat deposits tend to reallocate across the belly, thighs, and buttocks after menopause. As a result, supporting fat beneath the skin of the hands, face, neck, and arms begins to deteriorate, allowing drooping wrinkles to appear and the skin over these areas to become more easily squeezed as it loses its elasticity. When the skin is exposed to UV radiation, which causes elastosis, the reduced estrogen levels result in less collagen and elastin synthesis and healing in the dermis. Estrogens also stimulate melanin production, which may result in brown "age spots" on the arms, hands, face, neck, and chest of many women. All of these changes cause skin to mature (age) more quickly. Estrogen replacement both suppresses and restores these characteristics, but it has been associated to a slew of negative side effects. Genistein has been utilized as an alternative therapy for menopausal symptoms in the past,[88–92], and given the findings on skin aging, it may be regarded an effective menopause substitute treatment.
A review of wound dressing materials and its fabrication methods: emphasis on three-dimensional printed dressings
Published in Journal of Medical Engineering & Technology, 2022
S. Pravin Kumar, Yuvasri Asokan, Keerthana Balamurugan, B. Harsha
Skin is made up of two primary layers called the epidermis and dermis. The epidermis is the outermost layer of skin and it prevents pathogens from invading our body. The dermis is present underneath the epidermis which consists of connective tissues, nerve endings, sebaceous glands, and blood vessels. Apart from providing strength and flexibility to the skin, it is also responsible for the sense of touch, pain, and production of sebum. Dermis and epidermis are connected by basement membranes. Extracellular matrix (ECM) is a gel-like matrix produced by their surrounding cells. ECM is the largest component of the dermal layer and is crucial for wound healing. Wounds affect the continuity of the skin and might be caused due to cuts, burns, mechanical trauma, or surgery (Figure 1). The wound also impairs the functions of the skin which eventually leads to skin death. Applying wound dressing is an important measure to avert such complications. In an open wound, there is an extraneous break in the tissues, especially the skin. When skin rubs against a rough and hard surface, the resulting injury is called an abrasion (Figure 1(a)). A laceration is a deep cut in the skin and is mostly caused due to knives and other machinery (Figure 1(b,c)) while abrasions are caused due to road accidents. Burns are caused due to the exposure of the skin to extreme heat, flame, chemicals, etc. When the body is subjected to excessive force or pressure, the resulting injury is called crush injury (Figure 1(d)).
Effects of anti-wrinkle and skin-whitening fermented black ginseng on human subjects and underlying mechanism of action
Published in Journal of Toxicology and Environmental Health, Part A, 2020
Jin Ju Park, Junmin An, Jung Dae Lee, Hyang Yeon Kim, Jueng Eun Im, Eunyoung Lee, Jaehyoun Ha, Chang Hui Cho, Dong-Wan Seo, Kyu-Bong Kim
The dermis, a layer of the skin, which occurs beneath the epidermis, consists primarily of connective tissues comprised mainly of fibers (collagen and elastin fibers) and extrafibrillar matrix (ground substance) (Marks and Miller 2018). Fibroblasts are the most common type of cell in dermis, which synthesize the extracellular matrix including collagen and elastin. Collagen and elastin fibers play a key role in maintenance of skin firmness and elasticity of normal skin (Bateman, Lamande, and Ramshaw 1996). Generally, collagen and elastin fibers form a three-dimensional structure. Collagen, especially type I, accounts for approximately 90% of the content of connective tissue in the skin. Collagen is formed from a precursor called procollagen, which is produced by fibroblasts. Procollagen is secreted in the form of a propeptide as peptide base sequences at the amino and carboxyl-terminal ends. The propeptide is cleaved and separated from procollagen simultaneously with collagen polymerization, which aids in folding in the endoplasmic reticulum (Oikarinen et al. 1992; Parfitt et al. 1987; Talwar et al. 1995). Therefore, the quantity of separated procollagen reflects the quantity of synthesized collagen. Connective tissue of the skin contains elastin as well as collagen. Elastin constitutes only approximately 3–4% of the connective tissue (So et al. 2007); however together with collagen, elastin maintains the shape and firmness of skin. The structure of elastin is transformed by elastase by using elastin as a substrate. Thus, an increase of elastase results in the degradation of elastin, which leads to development of wrinkles (Tsuji et al. 2001; Tsukahara et al. 2001).