Gland
Juxtaglomerular apparatus
A local sensor linking tubular salt to vascular control
High-yield
Its three recognized components are macula densa, renin-containing granular cells and extraglomerular mesangial cells. Renin cells lie mainly in the terminal afferent arteriolar wall.
Overview
Where a nephron's distal straight tubule returns to its corpuscle, specialized epithelial and vascular cells form the juxtaglomerular apparatus. The macula densa samples tubular salt delivery, while granular vascular cells release renin. Extraglomerular mesangial cells occupy the intervening region.
Reference facts
- Location
- At the cortical corpuscle's vascular pole, where terminal thick ascending limb contacts the afferent/efferent arteriolar region.
- Hormones
- Granular cells release renin, an enzyme initiating angiotensin production. Renal erythropoietin normally comes chiefly from interstitial fibroblast-like cells rather than this apparatus.
- Blood supply
- Closely associated with the terminal afferent arteriole and adjacent glomerular vascular pole.
- Innervation
- Sympathetic beta-1 stimulation promotes renin release; reduced arteriolar pressure and reduced macula-densa salt delivery are additional major signals.
- Function
- Coordinates single-nephron filtration through tubuloglomerular feedback and contributes to systemic pressure and volume regulation through renin.
Clinical correlation
Reduced renal arterial perfusion can stimulate renin and contribute to renovascular hypertension. Angiotensin-mediated support of filtration becomes especially relevant when severe arterial disease affects both kidneys or a solitary functioning kidney.
Frequently asked questions
Where is the juxtaglomerular apparatus located?
At the cortical corpuscle's vascular pole, where terminal thick ascending limb contacts the afferent/efferent arteriolar region.
What does the juxtaglomerular apparatus secrete?
Granular cells release renin, an enzyme initiating angiotensin production. Renal erythropoietin normally comes chiefly from interstitial fibroblast-like cells rather than this apparatus.
What does the juxtaglomerular apparatus do?
Coordinates single-nephron filtration through tubuloglomerular feedback and contributes to systemic pressure and volume regulation through renin.
What is the blood supply of the juxtaglomerular apparatus?
The juxtaglomerular apparatus is supplied by the closely associated with the terminal afferent arteriole and adjacent glomerular vascular pole.