Secretion, regulation

Constitutive secretion Regulated secretion Neuronal secretion... 

Antidiuretic hormone is a posterior pituitary peptide hormone that binds to vasoconstrictive Via receptors (via Gaq to activate PLC and thence increase cytsosolic Ca2+), to V2 receptors (causing kidney water reabsorption via Gas and increased cAMP) and to corticotropin secretion-regulating Vlb (V3) receptors (mediated by Gaq to activate PLC and thence increase cytosolic Ca2+). For bioactive-G protein interactions see Table 5.9. 

Putative intracellular messengers involved in NGF synthesis and secretion regulation... 

Platelets are non-nucleated cells present in the blood whose major role is to form mechanical plugs at the site of vessel injury and to secrete regulators of the clotting process and vascular repair. In the absence of platelets, leakage of blood from vents in small vessels is common. 

That is the difference between idealism and materialism for the idealist, we experience our situation as open insofar as we are engaged in it, while the same situation appears closed from the standpoint of finality, that is, from the eternal point of view of the omnipotent and all-knowing God who alone can perceive the world as a closed totality for the materialist, the openness goes all the way down, that is, necessity is not the underlying universal law that secretly regulates the chaotic interplay of appearances—it is the All itself which is non-All, inconsistent, marked by an irreducible contingency. ... 

As has been discussed, add secretion Is a regulated process, and the taiget for this regulation is the parietal cell, with a variety of receptors on Its cell surface. But beyond this cellular taiget Is the proton pump itself, the H,K ATPase. All natural stimuli and inhibitors converge to activate or Inhibit this P-type ATPase. The parietal cell has developed extraordinary measures to be able to regulate the act of add secretion. Regulation of add secretion at the cellular... 

In unprocessed foods, potassium occurs mainly in association with bicarbonate-generating precursors such as citrate and, to a lesser extent, with phosphate. In processed foods to which potassium is added and in supplements, the form of potassium is potassium chloride. In healthy people, approximately 85% of dietary potassium is absorbed. Most potassium (approximately 77-90%) is excreted in urine, whereas the remainder is excreted mainly in feces, with much smaller amounts excreted in sweat. Because most potassium that is filtered by the glomerulus of the kidney is reabsorbed (70-80%) in the proximal tubule, only a small amount of filtered potassium reaches the distal tubule. The majority of potassium in urine results from secretion of potassium into the cortical collecting duct, a secretion regulated by a number of factors including the hormone aldosterone. An elevated plasma concentration of potassium stimulates the adrenal cortex to release aldosterone, which in turn increases secretion of potassium in the cortical collecting duct. 

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