The Urinary SystemIntroductionKidney FunctionsUrinary System OrgansKidney LocationSlide 6External AnatomySlide 8Slide 9Position of the KidneysSlide 11Slide 12Slide 13Internal AnatomySlide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Blood SupplySlide 24Anatomy of the KidneysSlide 26Slide 27Slide 28Mechanisms of Urine ProductionSlide 30Slide 31Slide 32Slide 33Slide 34NephronsNephron - Renal CorpuscleSlide 37Slide 38Slide 39Slide 40Slide 41Slide 42Slide 43Slide 44Slide 45NephronSlide 47Slide 48Slide 49Slide 50Slide 51Slide 52Slide 53Slide 54Renal PhysiologyUretersSlide 57Slide 58Slide 59Slide 60Urinary BladderSlide 62Slide 63Slide 64Slide 65Slide 66Slide 67UrethraSlide 69Slide 70Slide 71Slide 72Slide 73Slide 74MicturitionSlide 76Slide 77Slide 78Chapter 26The Urinary SystemChapter 23IntroductionThe kidneys are perfect examples of homeostatic organsMaintain constancy of fluids in our internal environmentFilter 200 liters of fluid a dayRemove toxins, metabolic wastes, and excess ions to leave the body in urineReturn needed substances to the bloodA primary organ of excretionKidney FunctionsKidneys regulate volume and chemical makeup of the bloodMaintain the proper balance between water and salts as well as between acids and basesGluconeogenesis - supply glucose during fastingProduce enzyme renin which helps regulate blood pressure and kidney functionProduce hormone erythropoietin which stimulates red blood cell productionUrinary System OrgansStructures of the urinary system include;–Kidneys–Urinary bladder–Ureters–UrethraKidney LocationThe kidneys extend approximately from the level of the 12th thoracic vertebra to the third lumbar vertebraThey receive some protection from ribsKidney LocationThe right lies somewhat lower than left as it is positioned under liverThe lateral surface of each kidney is convex, while the medial is concaveExternal AnatomyThe adult kidney weights about 150 g (5 oz.)Dimensions are 12 cm long, 6 cm wide, 3 cm thickExternal AnatomyMedial surface has a vertical cleft called the renal hilus that leads into the space within the kidney called the renal sinusAtop each kidney is an adrenal gland which is unrelated to kidney functionExternal AnatomyStructures such as the ureters, the renal blood vessels, lymphatics, and nerves enter the kidney at the hilusThese structures occupy the renal sinusPosition of the KidneysThe kidneys are retroperitoneal, or behind the peritoneumPosition of the KidneysKidneys supported by three layers of supportive tissueThe renal capsule adheres directly to the kidney surface and isolates it from surrounding regionPosition of the KidneysThe adipose capsule attaches the kidney to the posterior body wall and cushions it against traumaPosition of the KidneysThe renal fascia is dense fibrous connective tissue which surrounds the kidney and anchors these organs to the surrounding structuresInternal AnatomyThe kidney has three distinct regions–Cortex–Medulla–PelvisInternal AnatomyThe most superficial regionThe renal cortex is light in color and has a granular appearanceInternal AnatomyDeep to the cortex is the renal medullaDarker tissue which exhibits cone shaped tissue masses called medullary or renal pyramidsMedullarypyramidsInternal AnatomyEach renal pyramid has a base which is convex, and a apex which tapers toward its apex or papillaMedullarybaseMedullaryapexInternal AnatomyThe apex, or papilla, points internallyThe pyramids appear striped because they are formed almost entirely of roughly parallel bundles of urine collecting tubulesPyramidal stripesInternal AnatomyInward extensions of cortical tissue called renal columns separate the pyramidsEach medullary pyramid is surrounded by a capsule of cortical tissue to form a lobeInternal AnatomyWithin the renal sinus is the renal pelvisThis flat, funnel shaped tube is continuous with the ureter leaving the hilusInternal AnatomyBranching extensions of the renal pelvis form 2-3 major calyces, each of which sub-divides to form several minor calycesThese cup shaped areas collect the urine which drain continuously from the papillaeInternal AnatomyUrine flows through the renal pelvis into the ureter, which transports it to the bladderThe walls of the calyces, pelvis, and ureter contain smooth muscle which contract to move urineBlood SupplyThe kidney continuously cleanse the blood and adjust its compositionKidneys possess an extensive blood supplyUnder normal resting conditions, the renal arteries deliver approximately one-fourth of the total systemic cardiac output (1200 ml) to the kidneys each minuteBlood SupplyThe renal arteries issue at right angles from the abdominal aortaEach renal artery divides into five segmental arteries that enter the hilusEach segmental artery divides into lobar and interlobar arteriesAnatomy of the KidneysThe main structural and functional unit of the kidneys is the uriniferous tubuleThe unit consists of a nephron and its collecting duct or tubuleAnatomy of the KidneysUriniferous tubules are separated from one another by small amounts of loose areolar connective called interstitial connective tissueAnatomy of the KidneysThe urine forming nephron is composed of–Renal corpuscle–Proximal convoluted tubule–Loop of Henle–Distal convoluted tubuleA collecting duct (collecting tubule)–Concentrating urineAnatomy of the KidneysThroughout its length the uriniferous tubule is lined by a simple squamous epithelium that is adapted for various aspects of the production of urineMechanisms of Urine ProductionThe uriniferous tubule produces urine through three interacting mechanisms–Filtration–Reabsorption–SecretionMechanisms of Urine ProductionIn filtration a filtrate of the blood leaves the kidney capillaries and enters the nephronThis filtrate resembles tissue fluid in that it contains all the small molecules of blood plasmaMechanisms of Urine ProductionAs filtrate proceeds through the uriniferous tubule, the filtrate is processed into urine by the mechanisms of reabsorption and secretionMechanisms of Urine ProductionDuring reabsorption, most of the nutrients, water, and essential ions are reclaimed from the filtrate, and returned to the blood of capillaries in the surrounding connective tissue99% of the volume of renal filtrate is reabsorbedMechanisms of Urine