Blood Supply of the Kidney
1. Arterial Supply:
Renal arteries from the abdominal aorta supply blood to the kidneys.
Branches include segmental, interlobar, arcuate, and interlobular arteries, ending in afferent arterioles.
2. Glomerular Circulation:
Afferent arterioles supply glomeruli for filtration, and efferent arterioles drain the blood.
3. Peritubular Capillaries and Vasa Recta:
👉🏻Peritubular capillaries surround cortical nephrons.
👉🏻Vasa recta are specialized vessels supporting the medulla and concentrating urine.
4. Venous Drainage:
Blood drains into interlobular, arcuate, interlobar veins, and eventually the renal vein.
👉🏻1. Autoregulation:
Maintains consistent RBF via:
🔹Myogenic response: Arteriolar constriction/dilation based on pressure.
🔹Tubuloglomerular feedback: Sensed by macula densa cells.
👉🏻2. Sympathetic Nervous System:
Activates during stress, reducing RBF by constricting renal arterioles.
👉🏻3. Hormonal Regulation:
♦️RAAS: Angiotensin II preferentially constricts efferent arterioles to preserve GFR.
♦️Prostaglandins: Dilate afferent arterioles, countering vasoconstriction.
♦️ANP: Dilates afferent arterioles and constricts efferent arterioles, increasing GFR.
👉🏻4. Local Mediators:
Nitric oxide promotes vasodilation, increasing RBF.
Endothelin causes vasoconstriction, reducing RBF.
👉🏻5. Pathological Conditions:
Hypotension, shock, diabetes, or hypertension can alter renal autoregulation and decrease RBF.