Thalassotherapy and Marine Cosmeceuticals
Leonel Pereira in Therapeutic and Nutritional Uses of Algae, 2018
In the epidermis, the predominant keratinocyte cells repair skin damage, while melanocytes contain melanin, thus determining skin color and protecting the skin from UV light (Brenner and Hearing 2007). Langerhans cells, a type of dendritic cell, provide a degree of immunity (Wollenberg et al. 1996), as they take up microbial antigens in the skin and transform microbial antigens into antigen presenting cells by interacting with T cells. Sebaceous glands produce an oily substance known as sebum that lubricates the skin, although the occlusion and infection of these can trigger acne (Zouboulis 2004). Receptors in the skin detect various environmental stimuli and respond accordingly, with mechanoreceptors detecting sensations and thermoreceptors detecting heat. These receptors can cause sweat glands to produce sweat, thus maintaining temperature—homeostasis, as well as getting rid of waste (Denda et al. 2007). Insulation is also provided in the subcutaneous layer of the skin, where fat is stored. Skin absorbs not only oxygen and water, but also certain drugs, such as topical steroids. In addition, skin is rich in 7-dehydrocholesterol, and when it is exposed to UV light, this substance is converted into vitamin D (cholecalciferol) (see also Chapter 2), which is otherwise obtained by dietary means, such as by ingesting dairy products (Chen et al. 2007).
Anatomy and Embryology of the External and Middle Ear
John C Watkinson, Raymond W Clarke, Christopher P Aldren, Doris-Eva Bamiou, Raymond W Clarke, Richard M Irving, Haytham Kubba, Shakeel R Saeed in Paediatrics, The Ear, Skull Base, 2018
The sebaceous glands produce an oily material (sebum) from the breakdown of their fat-containing cells which is usually excreted into the root canals of the hair follicles. The mixture of desquamated cells, cerumen and sebum forms wax. Human earwax is a Mendelian trait consisting of wet and dry forms. Dry wax, lacking cerumen, is yellowish or grey and brittle, while wet wax is brownish and sticky. The wet phenotype is dominant over the dry type, and is frequently seen in populations of European and African origins. East Asians show the dry phenotype and there are intermediate frequencies among the Native American and Inuit of Asian ancestry. A single-nucleotide polymorphism in the ABCC11 gene is responsible for the determination of earwax type, with the AA genotype corresponding to dry wax and GA and GG to wet wax.10 There is dispute with regard to the specific antibacterial activity of cerumen in in vitro studies.11,12 However, the areas of skin that take part in cerumen production have all the components of an active local immune system and probably protect the canal by an antibody-mediated local immune response.13
Structure and function of skin
Roger L. McMullen in Antioxidants and the Skin, 2018
Sebaceous glands can be associated with terminal or vellus hair fibers. In terminal hair, the sebaceous duct opens into the hair follicle canal. In vellus hair, the hair follicle canal and the acini of the sebaceous gland are in close proximity and lead into a principal hair follicle canal. The anatomical distribution of sebaceous glands is unique inasmuch they are not found in the palms of the hands and soles and dorsum of the feet.48 The size and density of the glands also depend on anatomical location.49 For example, the facial region contains the largest glands and the highest density of sebaceous glands is found in the scalp, forehead, face, and anogenital region.50,51 Sex and age are also determinant factors in the size and density of sebaceous glands. The morphological structure of the sebaceous gland consists of several-to-many acini, which contain sebaceous cells. As illustrated in Figure 1.14, the acini are located at the base of the gland and lead into a duct, which eventually makes its way to the hair follicle canal.
Anti-ageing peptides and proteins for topical applications: a review
Published in Pharmaceutical Development and Technology, 2022
Mengyang Liu, Shuo Chen, Zhiwen Zhang, Hongyu Li, Guiju Sun, Naibo Yin, Jingyuan Wen
Glands are partial appendages, and the sebaceous glands are the small oil-producing glands directly open to the skin's surface and attach to hair follicles. These glands are most abundant on the scalp and face. They secrete an antibacterial substance known as sebum, a mixture of free fatty acids, glycerides, and cholesterol (Wertz 2018). Sebum acts as a lubricant and is the source of SC plasticizing lipids. The essential function of sebum is to maintain the pH of the skin’s surface (Ma et al. 2019). Sweat glands are present in the lower layers of the dermis and are responsible for temperature regulation. Distributed all over the body, except around the areola, secretions from sweat glands are a diluted salt solution with a pH of around 5 (Ma et al. 2019). Conversely, the apocrine glands are only located in areas such as the armpit and perianal, and they are usually larger than other counterparts (Farah et al. 2020). These appendages also change during puberty, affecting the permeation of the skin (Hirt et al. 2019).
Efficacy of a one-session fractional picosecond 1064-nm laser for the treatment of atrophic acne scar and enlarged facial pores
Published in Journal of Cosmetic and Laser Therapy, 2021
Thanaporn Puaratanaarunkon, Pravit Asawanonda
Uneven skin texture has raised significant aesthetic concerns and can be a source of a negative impact on psychosocial well-being of individuals. In particular, acne vulgaris or acne prone skin patients who have high activity of sebaceous glands mostly deal with the disruption of skin surface, ranging from minimal visible depression from enlarged pores to more obvious disfigurement, like acne scar. High amounts of sebum excretion prominently enlarges the facial pores, which represent an opening of pilosebaceous units (1). These dynamic structures are also influenced by various factors including ethnicity, sex hormones, loss of elasticity and increased hair follicle volume (2,3). The prevalence of conspicuous pores is high among acne-prone patients owing to the hyperkeratinization process, which is one of the causes of pore formation. Furthermore, the inflammation of acne combined with the damage of elastic and collagen fibers induce fibrosis and a change in skin texture ultimately resulting in acne scar (4).
Efficacy of 595- and 1319-nm pulsed dye laser in the treatment of acne vulgaris: a narrative review
Published in Journal of Cosmetic and Laser Therapy, 2020
Martin Kassir, Gulhima Arora, Hassan Galadari, George Kroumpouzos, Andreas Katsambas, Torello Lotti, Domenico Piccolo, Stephan Grabbe, Eva Juchems, Mohamad Goldust
Longer wavelength infrared lasers such as 1319-nm can penetrate deep into skin and can hence target sebaceous glands (18–20). Neodymium-doped Yttrium Aluminum Garnet (Nd:Yag) 1320-nm laser has been reported as efficacious in trials (21,22). Water serves as its chromophore, generating thermal energy leading to dermal collagen remodeling. Also, direct action onto the sebaceous glands leads to reduced sebum production and improvement in acne(23). This laser has been used in combination with 589-nm PDL. Kang et al. used a combination of 589/1319-nm dual laser for treating acne. They reported a 85.7% decrease in acne severity by the fourth session(24). Gold et al. used a similar solid-state laser combination of 589/1319 nm and achieved a 30% reduction in échelle d’évaluation clinique des cicatrices d’acné (ECCA) score(25). This combination modality targets the superficial vascular component with the 589-nm laser and the deeper sebaceous pathology with the 1319-nm laser(26).
Related Knowledge Centers
- Exocrine Gland
- Hair Follicle
- Hand
- Meibomian Gland
- Skin
- Scalp
- Gland
- Face
- Sole
- Foot