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  2. Positive feedback - Wikipedia

    en.wikipedia.org/wiki/Positive_feedback

    A number of examples of positive feedback systems may be found in physiology. One example is the onset of contractions in childbirth , known as the Ferguson reflex . When a contraction occurs, the hormone oxytocin causes a nerve stimulus, which stimulates the hypothalamus to produce more oxytocin, which increases uterine contractions.

  3. Sodium channel - Wikipedia

    en.wikipedia.org/wiki/Sodium_channel

    This is an example of a positive feedback loop. The ability of these channels to assume a closed-inactivated state causes the refractory period and is critical for the propagation of action potentials down an axon .

  4. Reward system - Wikipedia

    en.wikipedia.org/wiki/Reward_system

    The reward system (the mesocorticolimbic circuit) is a group of neural structures responsible for incentive salience (i.e., "wanting"; desire or craving for a reward and motivation), associative learning (primarily positive reinforcement and classical conditioning), and positively-valenced emotions, particularly ones involving pleasure as a core component (e.g., joy, euphoria and ecstasy).

  5. Neural oscillation - Wikipedia

    en.wikipedia.org/wiki/Neural_oscillation

    Because all brain areas are bidirectionally coupled, these connections between brain areas form feedback loops. Positive feedback loops tend to cause oscillatory activity where frequency is inversely related to the delay time. An example of such a feedback loop is the connections between the thalamus and cortex – the thalamocortical radiations.

  6. Hypothalamic–pituitary–gonadal axis - Wikipedia

    en.wikipedia.org/wiki/Hypothalamic–pituitary...

    This bistability is most obvious in the transition between the follicular and luteal phases, and arises from interactions between positive and negative feedback loops involving GnRH, LH, FSH, estrogen, and progesterone. The kisspeptin system creates a switch-like mechanism driving the transition from negative to positive feedback.

  7. Autoregulation - Wikipedia

    en.wikipedia.org/wiki/Autoregulation

    An example is a system in which a protein P that is a product of gene G "positively regulates its own production by binding to a regulatory element of the gene coding for it," [14] and the protein gets used or lost at a rate that increases as its concentration increases. This feedback loop creates two possible states "on" and "off".

  8. Hypothalamic–pituitary–thyroid axis - Wikipedia

    en.wikipedia.org/wiki/Hypothalamic–pituitary...

    Low-T3 syndrome and high-T3 syndrome: Consequences of step-up hypodeiodination, e.g. in critical illness as an example for type 1 allostasis, [20] or hyperdeiodination, as in type 2 allostasis, including posttraumatic stress disorder. [12] Resistance to thyroid hormone: Feedback loop interrupted on the level of pituitary thyroid hormone receptors.

  9. Cell signaling - Wikipedia

    en.wikipedia.org/wiki/Cell_signaling

    Neurotransmitters represent another example of a paracrine signal. Some signaling molecules can function as both a hormone and a neurotransmitter. For example, epinephrine and norepinephrine can function as hormones when released from the adrenal gland and are transported to the heart by way of the blood stream.