Consists of outer cortical zone inner juxtamedullary zone and renal columns Renal lobe consists of renal pyramid overlying cortex area and of each adjacent renal column Parenchyma functional part of the kidney Exam 3 Review Know renal anatomy Renal Cortex most superficial part Renal Medulla most inner region Consists of renal pyramids This is the renal cortex and pyramids Trace the flow of urine Micro and macro anatomy of glomeruli and kidney Know how blood filtrate flows through kidney Before this point it is still filtrate collecting duct papillary duct minor calyx major calyx renal pelvis ureter bladder Blood Renal artery segmental artery interlobar artery arcuate artery interlobular artery afferent arteriole glomeruli efferent arteriole peritubular capillaries vasa recta peritubular venule interlobular vein arcuate vein interlobar vein segmental vein renal vein Filtrate Glomeruli endothelium fenestrations basal lamina filtration slit membrane pedicles of podocytes proximal convoluted tubule descending loop ascending loop distal convoluted tubule After this point it becomes the final urinary product Know filtration absorption secretion Filtration Absorption Completed in the renal corpuscle Permits water and small solutes glucose vitamins etc to pass but not plasma proteins blood cells and platelets Volume of filtrate is large because of large surface area thin and porous membrane and high glomerular capillary blood pressure NFP usually 10mmHg Return of most of the filtrate and many solutes to the bloodstream About 99 of filtered water reabsorbed Mostly done by the proximal convoluted tubule and descending loop of Henle Dist Conv tube and collecting ducts will reabsorb at varying rates Active and passive processes Paracellular reabsorption is done between adjacent tubule cells and is a passive process diffusion Transcellular reabsorption is done through an individual cell usually done by active transport and Na K pumps Na reabsorption is so important and done by primary active transport Na K pumps in BASOLATERAL MEMBRANE ONLY or secondary active transport symporters and antiporters Resorption PCT Resorption Loop of Henle Resorption DCT Collectin g duct Secretion Hormones affecting reabsorption and secretion The proximal convoluted tubule is responsible for obligatory water reabsorption Symporters for glucose amino acids lactic acid water soluble vitamins phosphate and sulfate exist in the PCT Solute reabsorption promotes osmosis creating a gradient In the loop of Henle glucose amino acids and other nutrients are reabsorbed WATER IS NOT COUPLED WITH SOLUTE REABSORPTION HERE Na K 2Cl symporters in the thick ascending limb and DCT function in Na and Cl reabsorption resorption of cations Osmolarity is significantly decreased in thick ascending limb Na Cl symporters reabsorb Na and Cl Major site where PTH stimulates resorption of Ca2 depending on body s needs Site of facultative water resorption Principal cells reabsorb Na and secrete K Intercalated cells reabsorb K and HCO3 bicarbonate ions and secrete H Transfer of material from blood into tubular fluid Helps control blood pH Helps eliminate substances from body The PCT secretes variable amounts of H NH4 and urea Na H antiporters in the PCT causes Na to be reabsorbed and H to be secreted Only by active transport Angiotensin II Aldosterone and Cl Secrete more K Parathyroid Hormone ADH vasopressin Atrial natriuretic peptide wall Released when blood volume pressure decreases Decreased GFR Enhances reabsorption of Na Cl and water in PCT Stimulates Aldosterone release Stimulates principal cells in collecting duct to reabsorb more Na Stimulates cells in DCT to reabsorb more Ca2 Works in facultative water reabsorption in DCT Increases water permeability Inserts aquaporin 2 in DCT and collecting duct principal cells Stimulated by large increase in blood volume stretching of cardiac Decreased blood volume pressure Inhibits reabsorption of sodium and water in PCT and collecting duct Suppresses secretion of ADH and aldosterone Stimulates mesengial cells of glomerulus to relax thus creating more surface area thus increasing GFR Increased GFR means more water filtration which means decreased BP Know how parasympathetic and sympathetic can affect filtrate Parasympathetic Sympathetic Rest and digest Parasympathetic NS does not really regulate urinary function Kidney blood vessels supplied by sympathetic NS fibers release norepinephrine causing vasoconstriction Both afferent and efferent arterioles will constrict Greater stimulation constricts afferent arterioles even more End result is a decrease in GFR Molecule pH mechanisms Tubular cells of the PCT and collecting tubules can alter filtrate pH and therefore blood pH These cells can affect blood pH with two coupled mechanisms o Reabsorption of bicarbonate ions into cell from filtrate o Secretion of hydrogen ions out of filtrate into cells The reabsorption of bicarbonate ions is dependent on the secretion of hydrogen ions Intercalated cells reabsorb K and HCO3 bicarbonate and secrete H Lots of terms Question or two about problems in the kidney Typical solutes normally present in urine are filtered and secreted substances that are nor reabsorbed If disease alters metabolism or kidney function traces of substances normally not present or normal constituents in abnormal amounts may appear Albuminuria Glycosuria Hematuria Ketonuria Presence of excessive albumin Indicates increase in permeability of filtration membranes due to injury or disease increased BP or irritation of kidney cells by substances such as bacterial toxins ether or heavy metals Presence of glucose in urine Usually indicates diabetes mellitus Occasionally caused by stress epinephrine secretion Epi stimulates breakdown of glycogen and liberation of glucose from liver Presence of RBC s Indicates pathological condition Acute inflammation of urinary organs due to disease or irritation from kidney stones Could also be caused by tumors trauma kidney disease contamination of sample by menstrual blood High levels of ketone bodies in urine Indicative of diabetes mellitus anorexia starvation or too little carbohydrate in diet Above normal level of bilirubin in urine Casts Bilirubin Urobilinogenuria Presence of urobilinogen breakdown product of hemoglobin May be due to hemolytic or pernicious anemia infectious hepatitis biliary obstruction jaundice cirrhosis congestive heart failure or infectious mononucleosis Tiny masses of material that