Hormone cascade

At each level of a hormonal cascade, feedback inhibition of earlier steps in the cascade is possible an unnecessarily elevated level of the ultimate hormone or of one of the intermediate hormones inhibits the release of earlier hormones in the cascade. These feedback mechanisms accomplish the same end as those that limit the output of a biosynthetic pathway (compare Fig. 23-11 with Fig. 6-28) a product is synthesized (or released) only until the necessary concentration is reached. 

Hormonal cascades, in which catalysts activate catalysts, amplify the initial stimulus by several orders of magnitude, often in a very short time (seconds). 

The key to subcutaneous water control depends upon control of the hormone Aldosterone. Obviously estrogen control is part of this hormone cascade action/reaction factor. But, our main focus is salt and water control, so Aldosterone is the key. 

EXERCISE AND NUTRIENT METABOLISM The Hormone Cascade System Growth Factors... 

Control of physiological responses often involves several hormones. In some systems, two or more hormones act in opposition to each other (e.g., insulin and glucagon in the regulation of blood glucose). In other control systems, several hormones act in information hierarchies. Section 16.4 begins with a description of the best-researched example of such a hierarchy, referred to as a hormone cascade mechanism. This is followed by a discussion of growth factors, specialized proteins that stimulate cell division in susceptible cells. 

Hormonal cascades such as those responsible for the release of cortisol and epinephrine result in large amplifications of the initial signal and allow exquisite fine-tuning of the output of the ultimate hormone (Fig. 

Bass, A.H. 1993. From brains to behavior hormonal cascades and alternative mating tactics in teleost fishes. Rev. Fish Biol. Fisheries, 3, 181—186. 

To date the most effective treatments for diabetic nephropathy target the RAS. It is clearly evident that the RAS play a fundamental role in the development of diabetic complications, specifically diabetic nephropathy. The introduction of ARBs and RAS antagonists into the treatment regimen of diabetic patients has markedly improved the rates of progression of diabetic nephropathy and subsequent end-stage renal disease. The renin-angiotensin system (RAS) is a co-ordinated hormonal cascade, which modulates vasoconstriction and facilitates renal-sodium absorption to maintain blood... 

The G-proteins are heterotrimers made of three families of subunits, a, P, and y, which can interact specifically with discrete regions on G-protein-coupled receptors. This includes most receptors for neurotransmitters and polypeptide hormones (see Neuroregulators). G-protein-coupled receptors also embrace the odorant receptor family and the rhodopsin-linked visual cascade. 

FIGURE 15.19 The hormone-activated enzymatic cascade that leads to activation of glycogen phosphorylase. 

Stimulation of glycogen breakdown involves consumption of molecules of ATP at three different steps in the hormone-sensitive adenylyl cyclase cascade (Figure 15.19). Note that the cascade mechanism is a means of chemical amplification, because the binding of just a few molecules of epinephrine or glucagon results in the synthesis of many molecules of cyclic / MP, which, through the action of c/ MP-dependent protein kinase, can activate many more molecules of phosphorylase kinase and even more molecules of phosphorylase. For example, an extracellular level of 10 to 10 M epinephrine prompts the for-... 

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