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The renin-angiotensin system (RAS), or renin-angiotensin-aldosterone system (RAAS), is a hormone system that regulates blood pressure, fluid, and electrolyte balance, and systemic vascular resistance. [2][3] When renal blood flow is reduced, juxtaglomerular cells in the kidneys convert the precursor prorenin (already present in the blood) into ...
Aldosterone stimulates Na + and water reabsorption from the gut, salivary and sweat glands in exchange for K +. Aldosterone stimulates secretion of H + via the H+/ATPase in the intercalated cells of the cortical collecting tubules; Aldosterone upregulates expression of NCC in the distal convoluted tubule chronically and its activity acutely. [18]
Vasopressin regulates the tonicity of body fluids. It is released from the posterior pituitary in response to hypertonicity and causes the kidneys to reabsorb solute-free water and return it to the circulation from the tubules of the nephron, thus returning the tonicity of the body fluids toward normal. An incidental consequence of this renal ...
The collecting duct system of the kidney consists of a series of tubules and ducts that physically connect nephrons to a minor calyx or directly to the renal pelvis.The collecting duct participates in electrolyte and fluid balance through reabsorption and excretion, processes regulated by the hormones aldosterone and vasopressin (antidiuretic hormone).
The DCT is lined with simple cuboidal cells that are shorter than those of the proximal convoluted tubule (PCT). The lumen appears larger in the PCT than the DCT lumen because the PCT has a brush border (microvilli). DCT can be recognized by its numerous mitochondria (even though it is not as much as PCT), basal enfoldings and lateral membrane ...
Hyperaldosteronism (the syndrome caused by elevated aldosterone) is commonly caused by either idiopathic adrenal hyperplasia or by an adrenal adenoma. The two main resulting problems: Hypertension and edema due to excessive Na+ and water retention. Accelerated excretion of potassium ions (K+). With extreme K+ loss there is muscle weakness and ...
Both hormones exert their effects principally on the collecting ducts. Tubular secretion occurs simultaneously during re-absorption of filtrate. Substances, generally produced by body or the by-products of cell metabolism that can become toxic in high concentration, and some drugs (if taken). These all are secreted into the lumen of renal tubule.
The adrenal glands are located on both sides of the body in the retroperitoneum, above and slightly medial to the kidneys. In humans, the right adrenal gland is pyramidal in shape, whereas the left is semilunar or crescent shaped and somewhat larger. [8] The adrenal glands measure approximately 5 cm in length, 3 cm in width, and up to 1 cm in ...