Renal Lecture - R enal Lecture N PB 101L Renal system...

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Renal Lecture NPB 101L Renal system functions The renal system performs many important jobs: 1.Fluid balance Maintains H 2 O balance in the body Maintains proper plasma volume 3.Regulates osmolarity Regulates the quantity and concentration of most ECF ions, such as Na + , Cl - , K + , Ca 2+ , Mg 2 , H + , and HCO 3 - 3. Acid-Base balance 4. Waste removal 5.Hormone secretion Erythropoietin – stimulates RBC production Renin – triggers salt conservation mechanism Anatomy
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There are two of them – found on each side of the vertebral column They are retroperitoneal, meaning they lie outside the abdominal cavity Urine flows from the kidneys, through the ureters into the bladder, and is eliminated via the urethra
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The nephron is the functional unit of the kidneys There are over 1 million nephrons in each kidney Each nephron consists of a renal corpuscle and a tubule o The renal corpuscle is the initial filtering component. A filtrate is formed from the blood that is free of cells and proteins o The filtrate then enters the tubule, where substances are added and removed. o Filtrate passes from the tubule into the collecting duct, which empties into the ureter
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Renal Corpuscle Consists of a glomerulus and a Bowman’s capsule o The glomerulus is a network of capillary loops that protrudes into a fluid-filled capsule called Bowman’s capsule o The fluid between the capillaries and the capsule fills what is known as Bowman’s space Each glomerulus is supplied with blood by an afferent arteriole o As blood flows through the capillaries, about 20% of the plasma filters into the capsule, and the remaining blood leaves the glomerulus through the efferent arteriole o The blood is separated from the fluid by a three-layered filtration barrier All renal corpuscles are located in the cortex region The three steps to urine formation 1. Filtration – begins the process of urine formation. Fluid and small solutes are forced under pressure to flow from the glomerulus into Bowman’s space 2. Reabsorption – as the filtrate passes through the tubules, specific substances are reabsorbed back into the peritubular capillaries
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3. Secretion – some solutes are removed from the blood of the peritubular capillaries and secreted by the tubular cells into the filtrate Glomerular Filtration The process of filtering plasma from the glomerular capillaries into Bowman’s space The physical forces involved in glomerular filtration include glomerular capillary blood pressure, plasma-colloid osmotic pressure, and Bowman’s capsule hydrostatic pressure
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This note was uploaded on 03/15/2010 for the course NPB101L 83009 taught by Professor Liets during the Winter '09 term at UC Davis.

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Renal Lecture - R enal Lecture N PB 101L Renal system...

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