Macula densa

I want to introduct something about Retractable ball pen EC-177. 1)Retractable ball pen 2) Refill tip:0.7mm/1.0mm 3)One color printing on the clip 4)soft grip with black color In the kidney, the macula densa is an area of closely packed specialized cells lining the wall of the distal convoluted tubule (DCT) at the point of return of the nephron to the vascular pole of its parent glomerulus glomerular vascular pole.The cells of the macula densa are sensitive to the ionic content and water volume of the fluid in the DCT. If low water volume is detected by these cells, they will produce molecular signals that promote renin secretion by other cells of the juxtaglomerular apparatus. The release of renin is an essential component of the renin-angiotensin-aldosterone system (RAAS), which regulates blood pressure and volume.Contents1 Histology 2 Function 3 References 4 External links // HistologyThe cells of the macula densa are taller and have more prominent nuclei than surrounding cells of the distal convoluted tubule.The close proximity and prominence of the nuclei cause this segment of the DCT wall to appear darker in microscopic preparations, hence the name macula densa.FunctionSchematic depicting how the RAAS works. Here, activation of the RAAS is initiated by a low perfusion pressure in the juxtaglomerular apparatusA decrease in blood pressure corresponds to a decreased concentration of sodium and chloride ions at the macula densa and triggers an autoregulatory response to increase reabsorption of ions and water in order to return blood pressure to normal. Reduced blood pressure means decreased venous pressure and hence a decreased peritubular capillary pressure. This causes a smaller capillary hydrostatic pressure which causes an increased absorption of sodium ions into the vasa recta at the proximal tubule. Because of this increased absorption, less NaCl is present at the distal tubule which is where the macula densa is located. The macula densa senses this drop in salt concentration and responds through two mechanisms: first, it triggers dilation of the renal afferent arteriole, decreasing afferent arteriole resistance and thus offsetting the decrease in glomerular hydrostatic pressure caused by the drop in blood pressure. Second macula densa cells release prostaglandins, which triggers granular juxtaglomerular cells lining the afferent arterioles to release renin into the bloodstream. (The juxtaglomerular cells can also release renin independently of the macula densa, as they are also triggered by baroreceptors lining the arterioles, and release renin if a fall in blood pressure in the arterioles is detected.) Furthermore, activation of the sympathetic nervous system stimulates renin release through activation of beta-1 receptors.The process triggered by the Macula densa helps keep the glomerular filtration rate (GFR) fairly steady in response to varying artery pressure, due to dilation of the afferent arterioles and the action of Renin, which triggers constriction of the efferent arterioles, both of which increase hydrostatic pressure in the glomerulus.References^ Junqueira, Luiz C.; Jose Carneiro (2003). Basic Histology. McGraw-Hill. ISBN 0071378294. ^ Histology at BU 16010loa External linksOrganology at UC Davis Urinary/mammal/cortex1/cortex5 - "Mammal, kidney cortex (LM, Medium)" Physiology at MCG 7/7ch03/7ch03p17 - "The Nephron: Juxtaglomerular Apparatus" v?d?eUrinary system KidneyLayersRenal fascia? Renalcapsule? Renalcortex (Renal column)? Renalmedulla(Renalsinus,Renalpyramids,medullary interstitium)? Renal lobe? Cortical lobule? Medullaryray? NephronAfferent circulationRenalartery? Segmentalarteries? Interlobar arteries? Arcuatearteries? Cortical radial arteries? Afferentarterioles? Renalcorpuscle(Glomerulus, Bowman'scapsule)Renal tubuleProximal tubule? LoopofHenle (Descending, Thin ascending, Thickascending)? Distalconvolutedtubule? Connecting tubule? Collectingducts aka Duct of Belini? Renal papilla? Minor calyx? Major calyx? Renalpelvis? UreterEfferentcirculationGlomerulus? Efferentarterioles? Peritubular capillaries/ Vasarecta? Arcuate vein? Interlobar veins? RenalveinJuxtaglomerular apparatusMaculadensa? Juxtaglomerularcells? Mesangium/Extraglomerular mesangial cellFiltrationGlomerular basement membrane? Podocyte? Filtration slits? Mesangium/Intraglomerular mesangial cell? Tubular fluidRenal physiologyAcid base physiology? Fluid balanceCategories: Kidney anatomy(and so on) To get More information , you can visit some products about earth leakage circuit breaker, rechargeable d batteries, . The Retractable ball pen EC-177 products should be show more here!