How To Draw Renal Corpuscle & Juxtaglomerular Apparatus / Detailed Labeling / Easy / Step by Step скачать в хорошем качестве

How To Draw Renal Corpuscle & Juxtaglomerular Apparatus / Detailed Labeling / Easy / Step by Step

The Juxtaglomerular Apparatus (JGA) is a specialized microscopic structure located at the point where the distal convoluted tubule (DCT) of a nephron comes in close contact with the afferent arteriole of the same renal corpuscle. It plays a vital role in regulating both blood pressure and the glomerular filtration rate (GFR), ensuring the kidney maintains proper filtration and homeostasis. The JGA is composed of three main parts — the macula densa, the juxtaglomerular (JG) cells, and the extraglomerular mesangial cells, also called lacis cells. The macula densa consists of tightly packed, tall epithelial cells located in the wall of the distal convoluted tubule. These cells are sensitive to the concentration of sodium and chloride ions in the tubular fluid. When they detect a decrease in sodium levels, they send chemical signals to the nearby juxtaglomerular cells to release renin. The juxtaglomerular cells are modified smooth muscle cells found mainly in the wall of the afferent arteriole. They contain secretory granules filled with renin — an enzyme that triggers the renin–angiotensin–aldosterone system (RAAS). Through this mechanism, renin converts angiotensinogen (produced by the liver) into angiotensin I, which is then converted into angiotensin II by the angiotensin-converting enzyme (ACE) in the lungs. Angiotensin II causes blood vessels to constrict and stimulates the adrenal cortex to release aldosterone, leading to sodium and water reabsorption, thereby increasing blood pressure. The third component, the extraglomerular mesangial cells or lacis cells, are located between the afferent arteriole, efferent arteriole, and the distal convoluted tubule. These cells are believed to help in transmitting signals between the macula densa and juxtaglomerular cells and may also provide structural support and perform phagocytic functions. Together, these three components regulate the tubuloglomerular feedback mechanism, which maintains a stable glomerular filtration rate. When the sodium chloride concentration in the tubular fluid is high, the macula densa signals the afferent arteriole to constrict, reducing GFR. Conversely, when sodium levels are low, the afferent arteriole dilates, increasing GFR. Clinically, disorders of the JGA can result in abnormal renin secretion and hypertension. For example, a renin-secreting tumor can cause secondary hypertension, while chronic kidney disease can impair JGA function, affecting blood pressure regulation. Thus, the juxtaglomerular apparatus serves as a key link between the kidney and systemic blood pressure control, playing a crucial role in maintaining fluid and electrolyte balance in the body.Queries Solved in the Juxtaglomerular Apparatus (JGA) Drawing: 1. Location of the JGA – at vascular pole where DCT meets afferent arteriole. 2. Components – macula densa, juxtaglomerular cells, extraglomerular mesangial (lacis) cells. 3. Function of macula densa – senses Na⁺ and Cl⁻ concentration in tubular fluid. 4. Function of JG cells – secrete renin when BP or Na⁺ falls. 5. Location of JG cells – wall of afferent arteriole near glomerulus. 7. Regulation of BP – through renin–angiotensin–aldosterone system (RAAS). 8. Regulation of GFR – via tubuloglomerular feedback mechanism. 9. Effect of low Na⁺ – macula densa → renin release → vasoconstriction → ↑BP. 10. Effect of high Na⁺ – afferent arteriole constriction → ↓GFR. 11. Relation between DCT and afferent arteriole – close contact allows communication. 12. Histology of JG cells – modified smooth muscle cells with renin granules. 13. Result of renin secretion – angiotensin II formation and aldosterone release → ↑BP & Na⁺ retention. 14. Homeostatic role – maintains blood pressure, fluid, and electrolyte balance. 15. Clinical relevance – renin-secreting tumors and hypertension, altered BP control in kidney disease. #RenalCorpuscle #JuxtaglomerularApparatus #MaculaDensa #JGCells #MesangialCells #KidneyHistology #MedicalDrawing #AnatomyIllustration #NephronStructure #HumanPhysiology #Glomerulus #RenalAnatomy #MedicalStudents #HistologyArt #BiomedicalEducation