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The first principle is positive feedback. In computer models, a molecule that can be either membrane-associated or cytoplasmic can polarize when its association with the membrane is subject to positive feedback: that membrane localization occurs most strongly where the molecule is already most highly concentrated.
Positive feedback is used in digital electronics to force voltages away from intermediate voltages into '0' and '1' states. On the other hand, thermal runaway is a type of positive feedback that can destroy semiconductor junctions. Positive feedback in chemical reactions can increase the rate of reactions, and in some cases can lead to explosions.
In the physiology of the kidney, tubuloglomerular feedback (TGF) is a feedback system inside the kidneys. Within each nephron , information from the renal tubules (a downstream area of the tubular fluid ) is signaled to the glomerulus (an upstream area).
During the follicular phase, rising estrogen levels from developing follicles exert positive feedback on the hypothalamus and pituitary, leading to the LH surge that triggers ovulation. After ovulation, the corpus luteum produces progesterone, which inhibits GnRH secretion from the hypothalamus and gonadotropin release from the anterior ...
Depolarization is essential to the function of many cells, communication between cells, and the overall physiology of an organism. Action potential in a neuron, showing depolarization, in which the cell's internal charge becomes less negative (more positive), and repolarization, where the internal charge returns to a more negative value.
The Hodgkin cycle represents a positive feedback loop in which an initial membrane depolarization leads to uncontrolled deflection of the membrane potential to near V Na. The initial depolarization must reach or surpass a certain threshold in order to activate voltage-gated Na + channels .
Thyrotropic feedback control on a more detailed and quantitative level. [3] Thyroid homeostasis results from a multi-loop feedback system that is found in virtually all higher vertebrates. Proper function of thyrotropic feedback control is indispensable for growth, differentiation, reproduction and intelligence.
Paracrine signaling between neighboring cells creates this positive feedback loop. Thus, the constitutive transcription of upregulated proteins form ideal environments for tumors to arise. [ 12 ] Effectively, multiple bindings of ligands to the RTK receptors overstimulates the Ras-Raf-MAPK pathway, which overexpresses the mitogenic and invasive ...