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Endocrine signaling involves the release of hormones by internal glands of an organism directly into the circulatory system, regulating distant target organs. In vertebrates , the hypothalamus is the neural control center for all endocrine systems.
Endocrine disease is characterized by misregulated hormone release (a productive pituitary adenoma), inappropriate response to signaling (hypothyroidism), lack of a gland (diabetes mellitus type 1, diminished erythropoiesis in chronic kidney failure), or structural enlargement in a critical site such as the thyroid (toxic multinodular goitre).
In vertebrates, endocrine glands are specialized organs that secrete hormones into the endocrine signaling system. Hormone secretion occurs in response to specific biochemical signals and is often subject to negative feedback regulation. For instance, high blood sugar (serum glucose concentration) promotes insulin synthesis.
The presence of hormone or multiple hormones enables a response in the receptor, which begins a cascade of signaling. The hormone receptor interacts with different molecules to induce a variety of changes, such as an increase or decrease of nutrient sources, growth, and other metabolic functions.
The endocrine system refers to when the hormones from a cell affect another cell that is very distant from the one that released the hormone. Paracrine physiology has been understood for decades now and the effects of paracrine hormones have been observed when for example, an obesity associate tumor will face the effects of local adipocytes ...
[112] [113] Evidence suggests Notch signaling regulates the progressive recruitment of endocrine cell types from a common precursor, [114] acting through two possible mechanisms. One is the "lateral inhibition", which specifies some cells for a primary fate but others for a secondary fate among cells that have the potential to adopt the same fate.
Several hormones can affect insulin secretion. Estrogen is correlated with an increase of insulin secretion by depolarizing the β-cells membrane and enhancing the entry of Ca 2+. In contrast, growth hormone is known to lower the serum level of insulin by promoting the production of insulin-like growth factor-I (IGF-I).
By contrast, the hormones of the anterior pituitary gland (the adenohypophysis) are secreted from endocrine cells that, in mammals, are not directly innervated, yet the secretion of these hormones (adrenocorticotrophic hormone, luteinizing hormone, follicle-stimulating hormone, thyroid-stimulating hormone, prolactin, and growth hormone) remains ...