Comparative Anatomy, Physiology, and Biochemistry of Mammalian Skin
David W. Hobson in Dermal and Ocular Toxicology, 2020
There are two types of sweat glands in man, the eccrine and apocrine glands. The eccrine sweat glands are distributed over the entire body surface except for a few specific regions. They are numerous in the palms and soles. These glands develop independently of hair follicles and are situated in the deep dermis. They traverse the epidermis via a duct to open directly onto the surface of the skin. These glands are simple coiled tubular structures with four major components: the terminal secretory portion, the coiled duct, the straight duct, and the intraepidermal duct. Three types of cells have been described in the eccrine sweat gland secretory coil region. At the periphery of the secretory portion are the myoepithelial cells, which sit on the basement membrane. Clear cells have been observed with lipid inclusions. Intracellular canaliculi pass in between adjacent clear cells. These cells are responsible for producing the aqueous sweat. The last cell type is the dark cell which produces mucin. On the luminal surface of the dark cell, microvilli are located.229–232 Eccrine sweat glands are innervated by postganglionic sympathetic nerve fibers. Blood vessels surround the secretory portion and coil around the ducts of the sweat glands. Eccrine sweat glands are found only in a few mammals with hair. When present, they are usually restricted to the digital pads or the snout.230
Temperature Regulation
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal in Principles of Physiology for the Anaesthetist, 2020
Responses to high temperatures are aimed at decreasing heat gain and increasing heat loss. Decreased heat gain is achieved by behavioural changes (reduced activity, reduced feeding and reduced heat gain from the environment using appropriate clothing and housing). Sweating is the main method of increasing heat loss as the environmental temperature increases. There are about two million sweat glands in the body, but these are not evenly distributed. About 50% of the sweat production occurs in the chest and back, and women have lower rates of sweat production compared with men. Although the maximum rate of producing sweat is 3 L/h, this cannot be sustained, and the maximum amount of sweat produced is 12 L/day. The proximal region of the sweat gland produces a hypotonic solution that is modified by solute reabsorption as the fluid moves along the duct towards the skin surface. At low rates of secretion, the sodium content of sweat is low (5 mmol/L), but at high secretion rates, it can reach 10 times the basal value because there is less time for ductal reabsorption. Evaporation of sweat is important for heat loss; the latent heat of evaporation of water at 37°C is 2.4 kJ/mL, and the majority of this heat comes from the body.
Actions of Dopamine on the Skin and the Skeleton
Nira Ben-Jonathan in Dopamine, 2020
As shown in Figure 11.8 and is detailed in Table 11.1, the skin has two types of sweat glands. One type are the apocrine sweat glands, which secrete fluid into the sac of the hair follicle through which it comes out on the skin. The other type are the eccrine sweat glands, which secrete sweat directly onto the surface of the skin. Accordingly, apocrine glands are located deep in the layers of the skin while eccrine glands are more superficially placed. Sweat glands are composed of an intraepidermal spiral duct, a dermal duct made of a straight and a coiled portion, and a secretory tubule, coiled deep in the dermis or hypodermis. The coiled portion is formed by two concentric layer of columnar or cuboidal epithelial cells. The epithelial cells are interposed by myoepithelial cells that support the secretory epithelial cells. The duct of the gland is formed by two layers of cuboidal epithelium and open through the sweat pore. The secretory part of the apocrine glands is larger than that of eccrine glands.
Molecular docking study on europium nanoparticles and mussel adhesive protein for effective detection of latent fingerprints
Published in Biomarkers, 2023
T. R. Poorani, C. Ramya, Ramya Manohar
In latent fingerprint analysis, the fingerprint ejects different biomolecules and sweat gland residues. The skin surfaces are highly rich in eccrine sweat glands. These glands have a high content of calmodulin, dermcidin and keratin molecules. So, the formed fingerprints have these residues in a major ratio. While determining the fingermark pattern, the synthesised fluorescent material for visualisation of fingermarks interacted with these eccrine gland residues. In this study, the interaction between Eu2O3-MAP conjugate and synthesised Eunp-MAP conjugate with different eccrine gland residues was done through molecular docking for understanding and identifying their binding affinity and stability of the interaction. Docking analysis of bonding energy information for Eu2O3:MAP and Eunp:MAP conjugates with the eccrine gland proteins present in latent fingerprints is demonstrated in Table 2.
Sweat gland morphology and physiology in diabetes, neuropathy, and nephropathy: a review
Published in Archives of Physiology and Biochemistry, 2022
Sudha Singaram, Kalpana Ramakrishnan, Jayashree Selvam, Mallika Senthil, Vigneswaran Narayanamurthy
Sweat glands (SGs) are tiny coiled tubules available on dermal layers in abundance. It excretes sweat that contains minerals and salts; almost 80% of its constitution is water. The rate of sweating depends on physiological conditions. For example, when the internal temperature rises due to physical activity or hot external surroundings, the sweat rate increases, releasing more water. This leads to evaporation, making the body cool and thus helps in maintaining thermal regulation. Besides elevated temperature, sweating increases due to emotion, stress, and a few pathological conditions, including renal failure (Tang et al.2016, Baker 2019). Sweat contains salts like sodium, potassium, chloride, lactic acid, urea, etc. Concentrations of all these salts (except lactic acid and urea) are lesser in sweat when compared with serum. Turner and Avolio (2016) stated that sodium and potassium excretion increased during physical exercise. Also, it depends on the region of sweating. However, sweating also excretes toxic salts like urea and helps maintain electrolytic balance (Mickelsen and Keys 1943).
Sweat rate and sweat composition following active or passive heat re-acclimation: A pilot study
Published in Temperature, 2021
Lisa Klous, Cornelis de Ruiter, Puck Alkemade, Hein Daanen, Nicola Gerrett
Both WBSL and WBSR were measured and reported to provide insight in the whole-body sudomotor adaptations that occurred during five consecutive HRA days. WBSR was found to be similar between CH-CH and CH-HWI, but WBSL was higher in CH-CH compared to CH-HWI (Table 3). This can be explained by the twofold longer heat exposure time for the CH-CH group, which is also reflected by the thermal impulse. First and foremost, sweat glands must be active to adapt (i.e., be able to secrete more sweat) during HA [50]. These sudomotor adaptations may be elicited above a certain sweat rate, rather than total sweat volume. Support of this idea comes from work by Taylor et al. [51], suggesting that a WBSR of 0.4–0.8 L·h−1 is required to gain sudomotor adaptations. In the present study, WBSR exceeded this suggested threshold in both CH-CH and CH-HWI (Table 3), which potentially contributes to the explanation of similar sudomotor adaptations following active or passive HRA. With a comparable WBSR after active or passive HRA, similar amounts of heat can in theory be removed from the body. This has implications in sports or occupational settings where prolonged periods of heat exposure occur frequently.