Consists of two or three major calyces Fills most of renal sinus Connected to ureter, which drains kidney Nephrons Microscopic, tubular structures in cortex of each renal lobe Where urine production begins Blood Supply to Kidneys Kidneys receive 20–25% of total cardiac output 1200 mL of blood flows through kidneys each minute Kidney receives blood through renal artery Segmental Arteries Receive blood from renal artery Divide into interlobar arteries Which radiate outward through renal columns between renal pyramids Supply blood to arcuate arteries Which arch along boundary between cortex and medulla of kidney Afferent Arterioles Branch from each cortical radiate artery (also called interlobular artery) Deliver blood to capillaries supplying individual nephrons Cortical Radiate Veins (also called interlobular veins ) Deliver blood to arcuate veins Empty into interlobar veins Which drain directly into renal vein Renal Nerves Innervate kidneys and ureters Enter each kidney at hilum Follow tributaries of renal arteries to individual nephrons Sympathetic Innervation
Adjusts rate of urine formation By changing blood flow and blood pressure at nephron Stimulates release of renin Which restricts losses of water and salt in urine By stimulating reabsorption at nephron The Nephron Consists of renal tubule and renal corpuscle Renal tubule Long tubular passageway Begins at renal corpuscle Renal corpuscle Spherical structure consisting of: – glomerular capsule (Bowman’s capsule) – cup-shaped chamber – capillary network ( glomerulus ) Glomerulus Consists of 50 intertwining capillaries Blood delivered via afferent arteriole Blood leaves in efferent arteriole Flows into peritubular capillaries Which drain into small venules And return blood to venous system Filtration Occurs in renal corpuscle Blood pressure Forces water and dissolved solutes out of glomerular capillaries into capsular space Produces protein-free solution (filtrate) similar to blood plasma Three Functions of Renal Tubule 1. Reabsorb useful organic nutrients that enter filtrate 2. Reabsorb more than 90% of water in filtrate 3. Secrete waste products that failed to enter renal corpuscle through filtration at glomerulus Segments of Renal Tubule Located in cortex Proximal convoluted tubule (PCT) Distal convoluted tubule (DCT) Separated by nephron loop (loop of Henle) U-shaped tube Extends partially into medulla Organization of the Nephron
Traveling along tubule, filtrate (tubular fluid) gradually changes composition Changes vary with activities in each segment of nephron Each Nephron Empties into the collecting system : A series of tubes that carries tubular fluid away from nephron Collecting Ducts Receive fluid from many nephrons Each collecting duct
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