tubuloglomeruláris

Tubuloglomerular refers to a functional and anatomical relationship between the distal tubule of the nephron and the glomerulus. Specifically, it describes the JGA or juxtaglomerular apparatus, a specialized structure located where the distal convoluted tubule passes close to the afferent and efferent arterioles of its own glomerulus. The macula densa, a group of specialized cells in the wall of the distal tubule, senses changes in the sodium chloride concentration of the tubular fluid. When the macula densa detects an increase in sodium chloride, it signals the juxtaglomerular cells in the afferent arteriole. This signaling leads to vasoconstriction of the afferent arteriole, which in turn reduces glomerular filtration pressure and flow. Conversely, a decrease in sodium chloride concentration leads to vasodilation of the afferent arteriole, increasing glomerular filtration. This tubuloglomerular feedback mechanism is a crucial component of the body's intrinsic control of glomerular filtration rate (GFR), helping to maintain stable kidney function despite fluctuations in systemic blood pressure. It ensures that the GFR remains relatively constant, preventing both excessive filtration and insufficient filtration, which could damage the nephron or compromise the kidney's ability to excrete waste products. The tubuloglomerular feedback is a rapid and localized response that plays a vital role in long-term blood pressure regulation and maintaining extracellular fluid volume.