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Exposure Assessment
Published in Ted W. Simon, Environmental Risk Assessment, 2019
The skin provides a barrier to entry of substances into the body. The outer layer of the skin, or epidermis, is not vascularized. The stratum corneum is the outer layer of the skin and is about 10–40 μm thick. The stratum corneum is composed of keratinized and desiccated epidermal cells. This outer layer is highly hydrophobic because of its high lipid content, and this hydrophobicity contributes to the barrier function of the skin. Cells in the stratum corneum slough off or desquamate and are replaced by growing keratinocytes in the germinal layer of the epidermis below.
Alginate and Hydrogel Applications for Wound Dressing
Published in Se-Kwon Kim, Marine Biochemistry, 2023
Dina Fransiska, Ellya Sinurat, Fera Roswita Dewi, Hari Eko Irianto
Moreover, the skin performs many vital functions, including preventing water loss from the body, and it has a role in regulating body temperature. Normal human skin consists of three layers, including the epidermis, the dermis, and the hypodermis. The barrier function of the skin is provided by the epidermis, which is composed mainly of keratinocytes. They form a stratified epithelium, with basal keratinocytes at the innermost layer and the keratinized, relatively impermeable outer stratum corneum layer on the surface.
Potential application of Bioactive Compounds from agroindustrial Waste in the Cosmetic Industry
Published in Quan V. Vuong, Utilisation of Bioactive Compounds from Agricultural and Food Waste, 2017
Francisca Rodrigues, Ana F. Vinha, M. Antónia Nunes, M. Beatriz P. P. Oliveira
Skin has historically been used for the topical delivery of compounds. It is much more than a static, impenetrable shield against external insults. Rather, skin is a dynamic, complex, integrated arrangement of cells, tissues and matrix elements that regulate the body heat and water loss, whilst preventing the invasion of toxic substances and microorganisms. The re-use of bioactive compounds from food waste as cosmetic ingredients needs the knowledge of basic skin structure and absorption mechanisms. Skin has three major regions: epidermis, dermis and hypodermis. The skin barrier function is realized by a cornified layer of protein-rich dead cells (corneocytes) embedded in a lipid matrix, namely stratum corneum (Mathes et al. 2014). The lipid- enriched component consists predominantly of ceramides, as well as cholesterol and fatty acids (Schurer and Elias 1991). Interspersed amongst the keratinocytes, in the viable epidermis, are the cells that are involved in melanin production (melanocytes), sensory perception (Merkel cells) and immunological function (Langerhans and other cells) (Prow et al. 2011). Deeper skin layers are the viable epidermis (50–100 μm) with the basal membrane (consisting of at least one member of the protein family of laminin, type IV collagen and nidogen, and the proteoglycan perlecan) and the dermis (1–2 mm), where appendices like sweat glands and hair follicle are located (Franzen and Windbergs 2015, Schäfer-Korting et al. 2007). The dermis has an upper papillary layer containing loosely-arranged collagen fibers and a reticular layer with dense collagen fibers arranged parallel to the surface of the skin. As well as collagen, the dermal matrix comprises a high amount of elastin that provides the elastic properties of the skin (Mathes et al. 2014). This matrix is produced by fibroblasts, the main cell type of the dermis. Dermis is pervaded by blood and lymph vessels. Beneath the dermis lies the subcutis, also known as the hypodermis. The subcutis functions are insulator, conserving the body’s heat, and shock-absorber. Next to fibroblasts, adipocytes are the most prominent cell type in this compartment (Mathes et al. 2014). Figure 1 presents an overview of skin structure, referring to the local of action of active substances detailed in the next sections.
Quantitative risk modelling in the offshore petroleum industry: integration of human and organizational factors
Published in Ships and Offshore Structures, 2020
Xingwei Zhen, Jan Erik Vinnem, Xue Yang, Yi Huang
In order to propose or unify definition used when applying the concept of safety barrier in the offshore petroleum industry in Norway [47], the terminology of safety barrier involves the following levels: barrier function, barrier system, barrier element and barrier influencing factor. The definition and differences between these levels are presented as follows: Barrier function: A function planned to prevent, control, or mitigate undesired events or accidents.Barrier system: Technical, human and/or organisational measures designed and implemented to perform one or more barrier functions.Barrier element: A component of a barrier system that by itself is not sufficient to perform a barrier function.Barrier influencing factor: Conditions that influence the performance of barrier systems.