An introduction to skin and skin disease
Anupam Das, Sumit Sethi in Concise Dermatology, 2021
The skin is an extraordinary structure. It has a surface area of 2 m 2 and accounts for 16–20% of the total body weight. The accessory structures include hairs, nails, sebaceous, sweat glands, sensory receptors, etc. The skin surface is a barrier between living processes and the potentially injurious outside world. The hair follicle openings can also be seen at the skin surface and the diameter of these orifices and the numbers per cm vary greatly between anatomical regions. The junctional zone has considerable functional importance and is vital to understanding the pathophysiology of bullous disorders and many other skin diseases. Hair follicles are arranged all over the skin surface apart from the palms and soles, the genital mucosa, and the vermilion of the lips. The eccrine sweat glands are an extremely important part of the body's homeothermic mechanism in that the sweat secretion evaporates from the skin surface to produce a cooling effect.
Stem cells in the skin, its appendages, and other epithelial tissues
Mary L. Clarke, Jonathan Frampton in Stem Cells, 2020
In this chapter, the author takes a close look at the stem cells that underpin the skin and related epithelial surfaces, including the outer surface of the eye (the cornea) and the oral epithelium. Of the three germ layers of the developing embryo, the ectoderm represents the external layer that yields the epidermis and other stratified epithelia, including that in the mouth. These tissues give rise to a range of specialized appendages such as hair follicles, sweat glands, teeth, salivary glands, and mammary glands. Elaine Fuchs is a world leader in skin biology, her research focusing on the mechanisms that control the differentiation of the epidermis and its appendages from stem cells. Her approach to this research has been notable for its use of genetic approaches in defining how stem cell fate is determined and relating the function of individual genes to their role in human diseases when they are defective.
Depth of Anaesthesia
T.M. Craft, P.M. Upton in Key Topics In Anaesthesia, 2021
Consciousness and unconsciousness during anaesthesia probably exist at either end of a continuum. At low brain concentrations of anaesthetic agent patients will respond to verbal commands and have explicit memory of the event. Awareness during anaesthesia is a modern problem. In the mid-nineteenth century when only di-ethyl ether, No and chloroform were available to induce and maintain general anaesthesia, a state of unconsciousness was reached before the surgical planes of anaesthesia. The administration of intravenous benzodiazepines following a suspected episode of awareness does not guarantee retrograde amnesia and thus a lack of recall. Skin conductance is a quantification of sweat gland activity and decreases with increasing depth of anaesthesia. It is affected by drugs such as atropine and anticholinesterases. Heart rate variability maybe analysed during anaesthesia and be used to suggest trends in the depth of anaesthesia. A parameter that relates directly to the state of consciousness of an individual has yet to be defined.
Physiology of sweat gland function: The roles of sweating and sweat composition in human health
Published in Temperature, 2019
The purpose of this comprehensive review is to: 1) review the physiology of sweat gland function and mechanisms determining the amount and composition of sweat excreted onto the skin surface; 2) provide an overview of the well-established thermoregulatory functions and adaptive responses of the sweat gland; and 3) discuss the state of evidence for potential non-thermoregulatory roles of sweat in the maintenance and/or perturbation of human health. The role of sweating to eliminate waste products and toxicants seems to be minor compared with other avenues of excretion via the kidneys and gastrointestinal tract; as eccrine glands do not adapt to increase excretion rates either via concentrating sweat or increasing overall sweating rate. Studies suggesting a larger role of sweat glands in clearing waste products or toxicants from the body may be an artifact of methodological issues rather than evidence for selective transport. Furthermore, unlike the renal system, it seems that sweat glands do not conserve water loss or concentrate sweat fluid through vasopressin-mediated water reabsorption. Individuals with high NaCl concentrations in sweat (e.g. cystic fibrosis) have an increased risk of NaCl imbalances during prolonged periods of heavy sweating; however, sweat-induced deficiencies appear to be of minimal risk for trace minerals and vitamins. Additional research is needed to elucidate the potential role of eccrine sweating in skin hydration and microbial defense. Finally, the utility of sweat composition as a biomarker for human physiology is currently limited; as more research is needed to determine potential relations between sweat and blood solute concentrations.
Priming of the sweat glands explains reflex sweating in the heat
Published in International Journal of Hyperthermia, 2012
Steven Avila, Michael J. Buono
The purpose of this study was to determine whether reflex sweating during isometric handgrip exercise (IHG) in the heat was due to a priming effect in the sweat glands or an increase in skin temperature. Ten male subjects completed four trials where they performed IHG for three minutes at 40% of their maximal voluntary contraction (MVC). The four trials included: (1) a control trial in thermoneutral conditions (23 ± 1oC), (2) after sitting in hyperthermic conditions (35 ± 1oC) for 30 min, (3) a local heating trial after having their non-exercising arm wrapped in a heat pad that maintained forearm skin temperature at ∼35oC for 30 min, 4) and after pilocarpine iontophoresis to a 5 cm2 area of the forearm. The sweating rate (SR), as measured by resistance hygrometry, was not significantly different (P > 0.05) from baseline during IHG in either the control or local heating trial, but was significantly increased (P
Caruncular Tumor as the First Sign of T-Cell Lymphoma Relapse
Published in Seminars in Ophthalmology, 2015
Darren S. J. Ting, Qasim Mansoor, Susanna Mathew, Nicholas K. Wride
The lacrimal caruncle is a modified cutaneous tissue that contains hair follicles, accessory lacrimal glands, sweat glands, lobules of fat, and sebaceous glands. Due to the nature of tissue, a variety of lesions, both benign and malignant, could arise from this area. Lymphomas of the eye and its adnexa are frequently of B-cell lineage. We would like to report a rare and unique case of a patient presenting with a caruncular tumor of CD30-positive T-cell anaplastic large cell lymphoma (T-ALCL) origin, serving as the first, initial, sole sign of recurrence of previously treated cutaneous T-ALCL. We believe this to be the first such report in the literature. We aim to emphasize the importance of considering such a condition while formulating the differential diagnosis of caruncular tumour in patients with history of T-cell lymphoma and to characterize the clinical course of such a presentation.
Related Knowledge Centers
- Epidermis
- Exocrine Glands
- Hair Follicle
- Dermis
- Skin
- Sweat
- Eccrine Glands