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The outermost layer, the zona glomerulosa is the main site for the production of aldosterone, a mineralocorticoid. The synthesis and secretion of aldosterone are mainly regulated by the renin–angiotensin–aldosterone system. The zona glomerulosa cells express a specific enzyme aldosterone synthase (also known as CYP11B2).
Aldosterone upregulates epithelial sodium channels in the collecting duct and the colon, increasing apical membrane permeability for Na + and thus absorption. Cl − is reabsorbed in conjunction with sodium cations to maintain the system's electrochemical balance. Aldosterone stimulates the secretion of K + into the tubular lumen. [17]
In the adrenal glands, it is likely involved in the paracrine regulation of aldosterone secretion; in the heart and vasculature, it may be involved in remodeling or vascular tone; and in the brain, where it is largely independent of the circulatory RAS, it may be involved in local blood pressure regulation.
The HPA axis also interacts with the immune system through increased secretion of ACTH at the presence of certain molecules of the inflammatory response. [4] Mineralocorticoid secretion is regulated mainly by the renin–angiotensin–aldosterone system (RAAS), the concentration of potassium, and to a lesser extent the concentration of ACTH. [4]
The production of aldosterone is regulated via the renin-angiotensin II-aldosterone system, a system composed of baroreceptors and juxtaglomerular cells. [ 7 ] [ 8 ] Changes in the homeostasis of the human body, such as osmolality are detected by the system, which causes a chain reaction that ends with the adrenal gland either increasing or ...
The hypothalamus controls the anterior pituitary's hormone secretion by sending releasing factors, called tropic hormones, down the hypothalamo-hypophysial portal system. [3] For example, thyrotropin-releasing hormone released by the hypothalamus in to the portal system stimulates the secretion of thyroid-stimulating hormone by the anterior ...
The opposite mechanism is called transrepression. The hormone receptor without ligand binding interacts with heat shock proteins and prevents the transcription of targeted genes. Aldosterone and cortisol (a glucosteroid ) have similar affinity for the mineralocorticoid receptor; however, glucocorticoids circulate at roughly 100 times the level ...
Increased secretion of catecholamines are a hormone response regulated by the sympathoadrenal system (SAS) and the hypothalamic-pituitary-adrenal axis (HPAA). [10] The "fight or flight" response causes the secretion of hormones such as cortisol and adrenaline which stimulate additional physiological needs to increase respiratory, cardiac ...