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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.
Positive feedback loops play a role by switching cells from low to high Cdk-activity. The interaction between the two types of loops is evident in mitosis. While positive feedback initiates mitosis, a negative feedback loop promotes the inactivation of the cyclin-dependent kinases by the anaphase-promoting complex.
Positive feedback loops, on their own or in combination with negative feedback are a common feature of oscillating biological systems. [2] Examples
This kind of positive feedback at the single cell level and tissue level is responsible for symmetry breaking, which is an all-or-none process whereas once the symmetry is broken, the cells involved become very different. Symmetry breaking leads to a bistable or multistable system where the cell or cells involved are determined for different ...
Positive feedback occurs when the fed-back signal is in phase with the input signal. Under certain gain conditions, positive feedback reinforces the input signal to the point where the output of the device oscillates between its maximum and minimum possible states. Positive feedback may also introduce hysteresis into a circuit. This can cause ...
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.
This causes myometrial contraction and further positive feedback on the reflex. [1] [2] Studies among ewes demonstrated that the Ferguson reflex is blocked by epidural anesthesia. [3] In their studies among mice, Niles Newton and colleagues demonstrated the importance of cortical influences. [4]
Feedback on both the activator of a system and inhibitor make the system able to tolerate a wide range of concentrations. An example of this in cell biology is that activated CDK1 (Cyclin Dependent Kinase 1) activates its activator Cdc25 while at the same time inactivating its inactivator, Wee1, thus allowing for progression of a cell into ...