Electrolyte absorption disorders

The potent antidiuretic hormone AVP orchestrates the regulation of free water absorption, body fluid osmolality, cell contraction, blood volume, and blood pressure through stimulation of three G-protein-coupled receptor subtypes Vi-vascular types a and b, V2-renal, and V3-pituitary. Increased AVP secretion is the trademark of several pathophysiological disorders, including heart failure, impaired renal function, liver cirrhosis, and SIADH. As a consequence, these patients experience excess water retention or inadequate free-water excretion, which results in the dilution of sodium concentrations, frequently manifesting as clinical hyponatremia (serum sodium concentration <135mmol/L). This electrolyte imbalance increases mortality rates by 60-fold. Selective antagonism of the AVP V2 receptor promotes water... 

Q7 Laxatives are often misused/abused, for example in slimming disorders, to increase gut transit rate and so limit absorption of foods. Side effects which may occur include flatulence, and abdominal distension or discomfort with bulk-forming and osmotic laxatives. Other adverse effects may include diarrhoea, nausea, vomiting, weakness, dehydration and electrolyte imbalances, for example hypokalaemia. The most prominent side effect of the powerful stimulant/irritant laxatives is abdominal cramping, which is due to increased peristalsis. 

Diarrhoea results from an imbalance between secretion and reabsorption of fluid and electrolytes it has numerous causes, including infections with enteric organisms (which may stimulate secretion or damage absorption), inflammatory bowel disease and nutrient malabsorption due to disease. It also commonly occurs as a manifestation of disordered gut motility in the absence of demonstrable disease (see below). Rarely it is due to secretory tumours of the alimentary tract, e.g. carcinoid tumour or vipoma (a tumour which secretes VIP, vasoactive intestinal peptide). 

Disorders that cause increased secretion of fluid and electrolytes into the small intestine of the horse are characterized by abdominal discomfort, distension of the small intestine and enterogastric reflux. In young foals with small intestinal secretory disorders, diarrhea may occur. Increased intestinal secretion can result from the active secretion of electrolytes and water, for example the cyclic nucleotide-stimulated secretion that results from exposure to bacterial enterotoxins. Passive secretion of water can result from increased permeability of the intestine, such as in enteritis, distension or ischemia, or decreased absorption of osmoti-caUy active substances, such as with lactose intolerance in foals. Disorders in which there is decreased secretion of fluid into the small intestine are not appreciated, although impactions of ingesta in segments of the small intestine can occur. 

Xing and Dahn recently reported [68] that Qjr for disordered carbon and MCMB 2800 can be markedly reduced from about 180 and 30 mAh g to less than 50 and 10 mAh g respectively, when the carbon anode and cell assembly are made in an inert atmosphere and never come in contact with air. This indicates that these carbons contain nanopores that are not accessible to the electrolyte but are permeable to O2, CO2, and H2O. The absorption of these gases appears to be the dominant cause of the irreversible loss of capacity [68]. The peaks at about 0.7 and 0.3 V vs Li/Li+ in dQ/d Vcurves are assigned to electrolyte reduction and reactions with COH and COOH groups respectively. 

An electrolyte is a medium that is between the completely disordered gas and the well-ordered crystalline solid. Solutions have no long-range order, but a short-range order exists. This has been investigated by x-ray diffraction of water and of molten metals or by x-ray absorption spectroscopy (XAS). With decreasing temperature, one has an increasing... 

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