The document summarizes tubuloglomerular feedback and the juxtaglomerular complex. It describes two feedback mechanisms involving the afferent and efferent arterioles that depend on the juxtaglomerular complex near each nephron's glomeruli. The juxtaglomerular complex includes macula densa cells in the distal tubule and juxtaglomerular cells in the walls of the arterioles that synthesize and release renin in response to salt levels. Lacis cells also help regulate vasoconstriction and vasodilation of the renal arterioles and modify signals from the macula densa cells.

1. Copyright © 2011 by Saunders, an imprint of Elsevier Inc.
TUBULOGLOMERULAR FEEDBACK
• 2 feedback mechanism
• 1) afferent arterioles
• 2) efferent arterioles
• Both depend on juxtaglomerular complex/apparatus-
specialized organ near glomeruli of each nephron
• 1-macula densa cells (initial portion of distal tubule)
• 2-juxtaglomerular cells (walls of afferent & efferent
arterioles)

2. Copyright © 2011 by Saunders, an imprint of Elsevier Inc.
JG CELL
• Modified vascular smooth muscle cell
• Loc: media of afferent efferent arterioles
• Golgi, ER, mitochondria
• Synthesis store release –renin in granules

3. Copyright © 2011 by Saunders, an imprint of Elsevier Inc.
MACULA DENSA CELLS
• Location: distal tubule
• Group of specialized epithelial cell (cuboidal)
• Comes in close contact with afferent & efferent arterioles
• Secretory activity-golgi apparatus toward arterioles
• Close contact with JG & lacis cells
• Sensor-change in salt level in fluid distal tubule
• Protection-slight change in GFR when change in blood
pressure- 75-160 mmHg.

4. Copyright © 2011 by Saunders, an imprint of Elsevier Inc.
LACIS CELL
• Loc: extraglomerular mesangial cell, in angular space
between junction of afferent & efferent arterioles.
• Function: selective vasoconstriction / vasodilatation of
renal afferent & efferent arterioles
• Relay & modify signal to macula
• Secrete renin in extremity

5. Copyright © 2011 by Saunders, an imprint of Elsevier Inc.
Angiotensin II
• Aldosterone
• Potent vasoconstrictor of arterioles to ↑ BP
• ↑ noradrenaline
• ↑ efferent arteriole resistance
• ↓ afferent arteriole resistance
• ↑ ADH, CRH, ACTH & water intake

6. Copyright © 2011 by Saunders, an imprint of Elsevier Inc.
• SAME WILL OCCURE FOR UNCONTROLLED DIABETES.
• OPPOSITE WHEN PCT DAMAGE BY POISON MERCURY
OR TETRACYCLINE(RENAL VASOCONSTRICTION)