Search results
Results From The WOW.Com Content Network
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 occurs when a gene activates itself directly or indirectly via a double negative feedback loop. Genetic engineers have constructed and tested simple positive feedback networks in bacteria to demonstrate the concept of bistability. [28] A classic example of positive feedback is the lac operon in E. coli. Positive feedback plays ...
Short overview of thyroid homeostasis. [1]The hypothalamic–pituitary–thyroid axis (HPT axis for short, a.k.a. thyroid homeostasis or thyrotropic feedback control) is part of the neuroendocrine system responsible for the regulation of metabolism and also responds to stress.
Schematic of the HPA axis (CRH, corticotropin-releasing hormone; ACTH, adrenocorticotropic hormone) Hypothalamus, pituitary gland, and adrenal cortex The hypothalamic–pituitary–adrenal axis (HPA axis or HTPA axis) is a complex set of direct influences and feedback interactions among three components: the hypothalamus (a part of the brain located below the thalamus), the pituitary gland (a ...
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.
Thus, to Barcroft homeostasis was not only organized by the brain—homeostasis served the brain. [13] Homeostasis is an almost exclusively biological term, referring to the concepts described by Bernard and Cannon, concerning the constancy of the internal environment in which the cells of the body live and survive.
An example of positive feedback mechanism in the insulin transduction pathway is the activation of some enzymes that inhibit other enzymes from slowing or stopping the insulin transduction pathway which results in improved intake of the glucose. One of these pathways, involves the PI3K enzyme.
PGC-1α has been shown to exert positive feedback circuits on some of its upstream regulators: PGC-1α increases Akt (PKB) and Phospho-Akt (Ser 473 and Thr 308) levels in muscle. [21] PGC-1α leads to calcineurin activation. [22] Akt and calcineurin are both activators of NF-kappa-B (p65).