Kidney Blood & Nerve Supply

BLOOD SUPPLY:
Development:
  • Due to ascent of kidneys during development, the blood supply of kidney changes:?
  1. Initially when the kidneys are in pelvis, the renal arteries are branches of common iliac arteries.
  2.  Upto 5th week of intrauterine life, kidney is in lumbar region and renal arteries are branches of common iliac artery .
  3. After that, differential growth of abdominal wall causes the kidney to ascent to lumbar region. Adult position (lumbar region of abdomen) is attained by 9th week.
  4. Druing progressive ascent, the arteries to kidney are derived from different levels of aorta.
  5. After full ascent, definitive renal artery is branch of aorta at 2nd lumbar segment.
  6. Thus, neonatal kidney is supplied by aorta.
Arterial Supply:
  • The renal circulation supplies the blood to the kidneys via the renal arteries, left and right, which branch from left & right phrenic artery which branch directly from the abdominal aorta.
  • Posterior, apical, upper anterior, middle anterior and lower are 5 segments of vascular suplly in each kidney
  • Kidneys receive approximately 20% of the cardiac output.
  • Renal artery→Segmental arteries→Interlobar arteries(penetrate the renal capsule and extend through the renal columns between the renal pyramids)
  • Interlobar arteries supply→Arcuate arteries (run through the boundary of the cortex and the medulla) → Interlobular arteries → Afferent arterioles (supply the glomeruli)
  • The medullary interstitium is the functional space in the kidney beneath the individual filters (glomeruli), which are rich in blood vessels.
  • The interstitium absorbs fluid recovered from urine.
  • Right renal artery is longer and passes behind IVC
Venous Drainage:
  • Right renal vein is shorter than the left 
  • Left renal vein is longer and passes in front of abdominal aorta, behind the origin of superior mesenteric artery.
  • After filtration occurs, the blood moves through a small network of venules→interlobular veins.
  • As with the arteriole distribution, the veins follow the same pattern: Interlobular → Arcuate veins →Interlobar veins→Renal vein (exiting the kidney for transfusion for blood) NERVE
SUPPLY:
  • The kidney and nervous system communicate via the renal plexus, whose fibers course along the renal arteries to reach each kidney.
  • Input from the sympathetic nervous system triggers vasoconstriction in the kidney, thereby reducing renal blood flow.
  • The kidney also receives input from the parasympathetic nervous system, by way of the renal branches of the vagus
  •  nerve (cranial nerve X); the function of this is yet unclear. Sensory input from the kidney travels to the T10-11 levels of the spinal cord and is sensed in the corresponding dermatome.Thus, pain in the flank region may be referred from corresponding kidney.
Exam Question
  • Right renal vein is shorter than the left 
  • Superior suprarenal artery originates from Inferior phrenic artery
  • Initially when the kidneys are in pelvis, the renal arteries are branches of common iliac arteries
  • Neonatal kidney is supplied by aorta.
  • Right renal artery is longer and passes behind IVC
  • There are 5 vascular segment in kidney:Posterior, apical, upper anterior, middle anterior and lower.

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