Homeostatic systems

Cram, W.J. (1983). Chloride accumulation as a homeostatic system set points and perturbations. Jourrml of Experimental Botany, 34, 74-84. 

Many biological systems exhibit control types that mimic proportional control -or at least are described or modeled as proportional control - in particular homeostatic systems like regulation of temperature, pH, salt concentrations, etc. It is typical for these systems, however, that there are additional mechanisms that compensate for the sloppiness of the low gain. 

In studying the finer aspects of the regulation of the cell, we found it necessary to take into consideration what is, for the cell, the outside world of the body as a whole. Now that we have come so far as to begin to build up a biochemical picture of the whole body, it becomes necessary for us to take one final step. For the cell, the external environment is provided by the body, a homeostatic system which maintains the constancy of its internal composition and thus enables the cell to survive as part of an integrated whole,... 

There is another important member of the Ca homeostatic system. While vitamin D and PTH act together to increase the calcium level of the blood, calcitonin, a hormone of the thyroid gland, lowers the level of Ca + by promoting deposition of calcium in bone by the osteoblasts. The overall effect is to hold the concentration of Ca + in the blood at 2.2-... 

Body fluid osmolality is controlled by a homeostatic mechanism that adjusts both the rate of water intake and the rate of solute-free water excretion by the kidneys—i.e., water balance. Abnormah-ties in this homeostatic system can result from genetic diseases, acquired diseases, or drugs, and may cause serious and potentially life-threatening deviations in plasma osmolality. Arginine vasopressin is the main hormone that regulates body fluid osmolality. 

Vitamin D functions in the process of calcium mobilization from previously formed bone making it available to the extracellular fluid upon demand by the calcium homeostatic system as described under the regulation of vitamin D metabolism. From the experiments described in the metabolism section it is clear that 1, 25-(0H)2D3, rather than 25-OH-D3 or vitamin D3 functions in the mobilization of calcium from bone under physiologic conditions. The mechanism whereby 1,25-(0H)2D3 initiates mobilization of calcium from bone is not at all understood. In contrast to the response of intestinal calcium transport to 1, 25-(0H)2D3 this process is blocked by the prior administration of actinomycin D suggesting that in fact a transcriptive event is involved in this activation As previously pointed out, bone possesses a specific receptor for 1,25bone cells has not yet been determined however. In vivo the 1,25-(OH)2D3 activation of bone calcium mobilization requires the presence of parathyroid hormone but the nature of... 

The calcium homeostatic system, originally attributed exclusively to the parathyroid hormone, now includes the renal hormone la,25-di-hydroxyvitamin D3. Calcium is the fifth most abundant element in vertebrate systems and is the most important structural component of the body 45, 72). Calcium is also required for the following purposes ... 

METABOLIC BISORBERS ARISING FROM INBORN ERRORS OF METABOLISM WITHIN THE COPPER HOMEOSTATIC SYSTEM... 

Effects of pH Internal pH homeostatic System, transcription factor PacC A. nidulans The acid tolerance mechanism of Rhizopus sp. during fumaric add production remains uncharacterized Involvement of PacC needs to be investigated Caddick et al. (1986), Arts and Penalva (2003) Penalva et al. (2008)... 

The Endocrine Society defines an endocrine disrupting substance as a compound either natural or synthetic, which, through environmental or inappropriate developmental exposures, alters the hormonal and homeostatic systems that enable the organism to communicate with and respond to its environment. Effects may include developmental, reproductive, neurological, and immune system defects. The field is a controversial one most of the data come from wildlife studies, and the dose/response effect is problematic. In laboratory studies, many anthropogenic compounds... 

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