Homeostasis water

AVP plays a central role in water homeostasis of terrestrial mammals, leading to water conservation by the kidney. OT is primarily involved in milk ejection, parturition and in sexual and maternal behaviour. Both hormones are pqDtides secreted by the neurohypophysis, and both act also as neurotransmitters in the central nervous system (CNS). The major hormonal targets for AVP are the renal tubules and vascular myocytes. The hormonal targets for OT are the myoepithelial cells... 

Clinical Presentation of Impaired Sodium and Water Homeostasis... 

See Chap. 52, Disorders of Sodium and Water Homeostasis, authored by James D. Coyle and Melanie S. Joy Chap. 53, Disorders of Calcium and Phosphorus Homeostasis, authored by Amy Barton Pai, Mark Rohrscheib, and Melanie S. Joy and Chap. 54, Disorders of Potassium and Magnesium Homeostasis, authored by Donald F. Brophy and Todd W. B. Gehr, for a more detailed discussion of this topic... 

As already noted, nearly all the diuretics in common use exert their effects from within the lumen of the nephron. These drugs are in general highly protein-bound and are not filtered by the glomerulus. Instead, in common with many other drugs and organic molecules, they diffuse from the peritubular vasculature across the basolateral membrane of the proximal tubular cells and from there are actively secreted into the filtrate. The efficacy of a diuretic depends not only on the mass and rate of delivery of drug to the filtrate but also on the body s state of sodium and water homeostasis. 

AQP-1 Fluid reabsorption in proximal renal tubule secretion of aqueous humor in eye and cerebrospinal fluid in central nervous system water homeostasis in lung... 

Kjellbom, P., Larsson, C., Johansson, I., Karlsson, M., Johanson, U. (1999) Aquaporins and water homeostasis in plants. Trends Plant Sci. 4, 308-314. 

Natriuretic peptides (NPs) are a group of peptide hormones in animals that are critically involved in salt and water homeostasis (for review see [5]). NPs include atrial NP (ANP), brain NP (BNB), C-type NP (CNP), and urodilatin all of which are synthesized as larger precursor proteins. In... 

This effect could have reflected involvement of prolactin in adrenal steroidogenesis or salt and water homeostasis. 

Water homeostasis is a strict requirement for normal physiological function. The most important task of the human skin is thus to create a watertight enclosure of the body to prevent water loss. It is the intercellular lipid matrix of the outermost keratinized horny layer of the skin (possibly together with recently reported claudin-based tight-junctions Furuse et al., 2002) that represents the skin barrier proper as once this lipid matrix (composed foremostly of saturated long chain ceramides ( 50% wt/wt) and cholesterol (—30% wt/wt) (Wertz and Norlen, 2002)) has been removed, substances diffuse freely into or out of the body system (Blank, 1952 Breathnach et al., 1973 Elias and Friend, 1975). At the same time the intercellular lipid matrix ensures that the stratum corneum remains hydrated and thus the skin surface appears healthy and smooth. 

Water Homeostasis in the Brain Physiology of the Brain Fluids. 127... 

Kimelberg HK (2004) Water homeostasis in the brain basic concepts. Neuroscience 129 851-860 Kinouchi H, Epstein CJ, Mizui T, Carlson E, Chen SF, Chan PH (1991) Attenuation of focal cerebral ischemic injury in transgenic mice overexpressing CuZn superoxide dismutase. Proc Natl Acad Sd USA 88 11158-11162... 

Schrier RW. Aquaporin-related disorders of water homeostasis. Drug News Perspect. 2007 20 447-53. 

Maintenance of water homeostasis is paramount to life for all organisms. In mammals, the maintenance of osmotic pressure and water distribution in the various body fluid compartments is primarily a function of the four major electrolytes, Na", K , Cl", and HCOi". In addition to water homeostasis, these electrolytes play an important role in the maintenance of pH, proper heart and muscle function, oxidation-reduction reactions, and as cofactors for enzymes. Indeed, there are almost no metabolic processes that are not dependent on or affected by electrolytes. Abnormal concentrations of electrolytes may be either the cause or the consequence of a variety of disorders. Thus determination of electrolytes is one of the most important functions of the clinical laboratory. Interpretation of abnormal osmolality and acid-base values requires specific knowledge of the electrolytes. Because of their physiological and clinical interrelationship, this chapter discusses determination. of electrolytes, osmolality, acid-base status, and blood oxygenation. 

Figure 50-12 Key elements in water homeostasis. So/id //nes indicate osmotically stimulated pathways, and dashed lines Indicate volume-stimulated pathways.The dotted lines indicate negative feedback pathways. Abbreviations ANfl atrial natriuretic peptide AVP, arginine vasopressin CNS, central nervous system C/- extracellular fluid OPR, oropharyngeal reflex. (From Reeves W,AndreoliT.The posterior pituitary and water metabolism. /n Wj7son JD, Foster DW, eds. Williams textbook of endocrinology, 8tb ed. Philadelpbia WB Sounders Co, 1992 312.)...

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