Urinary System Introduction The urinary system Filters the body of waste materials,Homeostaticaly regulates bodys fluid status,electrolyte balance and acid base balance. Endocrine and Synthetic functions EPO –Controls RBC production from stem cells in marrow –Stimulated by reduced PO 2 in kidney (not systemic PO 2 ) Vitamin D –Active form (calcitrol) produced by a hydroxlation in kidney & liver –Important for calcium absortion from GI and also neuronal development in-utero Renin –An enzyme. Synthesized in juxtaglomerular (granular) cells in afferent arteriole –Stimulated by a fall in circulating volume –Leads to the production of Ang II and Aldosterone

Basic Anatomy of the Kidney Renal Hilus: Renal artery, vein, nerves, lymphatics & renal pelvis Cortex Medulla: Renal Pyramids Medullary rays Papilla

Internal Structure of the Kidney 85% 15%

Nephron Structure: Associated Blood Vessels Renal → segmental → interlobar → arcuate → cortical radial (interlobular) → afferent → glomerulus → efferent The Kidney Has The Highest Blood Flow Per Unit Mass Among Major Organs ml/min = 25% of cardiac output Two arterioles and two capillary beds in series

Nephron Structure