Page 104 - Physiology and Pathophysiology MNU 2024-2025 نظرى

Clinical pharmacy 2024/2025 Level 2 Pharm D Physiology and Pathophysiology (MD303)

Regulation of GFR

▪ Vasoconstriction or dilation of the afferent arterioles affects the rate of blood flow to the glomerulus➔ Affects GFR.
✓ Changes in diameter result from extrinsic and intrinsic mechanisms.
✓ Mechanisms to regulate GFR:
Sympathetic Regulation of GFR Renal Autoregulation of GFR

(Neural regulation of GFR)
▪ Stimulates vasoconstriction of afferent arterioles ➔ Preserves blood • Ability of kidney to maintain a constant GFR under systemic changes.

volume to muscles and heart.  Achieved through effects of locally produced chemicals on the
• Cardiovascular shock: afferent arterioles.

▪  glomerular capillary hydrostatic pressure. *  urine output (UO). ▪ When mean arterial blood pressure (MAP) drops to 70 mm Hg➔
afferent arteriole dilates.
▪ When MAP  ➔ vasoconstrict afferent arterioles.
(1)-Myogenic Mechanism of the autoregulation (fast)

(2)-Tubulo-glomerular feedback (slow)
✓ Increased flow of filtrate sensed by macula densa cells in thick
ascending LH.
✓ Signals afferent arterioles to constrict.

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