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General Anatomy of General Anatomy of Urinary SystemUrinary System
URINARY SYSTEM ORGANSURINARY SYSTEM ORGANS
Kidneys (2)Kidneys (2) Ureters (2)Ureters (2) Urinary bladderUrinary bladder UrethraUrethra
KIDNEY FUNCTIONSKIDNEY FUNCTIONS
Control blood volume and compositionControl blood volume and composition
KIDNEY FUNCTIONSKIDNEY FUNCTIONS
Filter blood plasma, eliminate wastesFilter blood plasma, eliminate wastes Regulate blood volume, pressureRegulate blood volume, pressure Regulate fluid osmolarityRegulate fluid osmolarity Secrete reninSecrete renin Secrete erythropoietin (EPO)Secrete erythropoietin (EPO) Regulate PRegulate PCOCO22, Acid-Base balance, Acid-Base balance Synthesize calcitriol (Vitamin D)Synthesize calcitriol (Vitamin D) Detoxify free radicals, drugsDetoxify free radicals, drugs GluconeogenesisGluconeogenesis
EXCRETIONEXCRETION
Removal of wastesRemoval of wastes Respiratory systemRespiratory system
COCO22, water, water Integumentary systemIntegumentary system
Water, salts, lactic acid, ureaWater, salts, lactic acid, urea Digestive systemDigestive system
Water, salts, COWater, salts, CO22, lipids, bile pigments, cholesterol, , lipids, bile pigments, cholesterol, etc.etc.
Urinary systemUrinary system Metabolic wastes, toxins, drugs, hormones, salts, HMetabolic wastes, toxins, drugs, hormones, salts, H++, ,
waterwater
KIDNEY ANATOMYKIDNEY ANATOMY
Protected by three connective tissue Protected by three connective tissue layerslayers
Renal fasciaRenal fascia Attaches to abdominal wallAttaches to abdominal wall
Adipose capsuleAdipose capsule Fat cushioning kidneyFat cushioning kidney
Renal capsuleRenal capsule Fibrous sacFibrous sac Protects from trauma and infectionProtects from trauma and infection
KIDNEY ANATOMYKIDNEY ANATOMY
Gross anatomyGross anatomy Renal sinusRenal sinus Renal parenchymaRenal parenchyma
KIDNEY ANATOMYKIDNEY ANATOMY
Renal sinusRenal sinus Surrounded by renal parenchymaSurrounded by renal parenchyma Contains blood & lymph vessels, nerves, Contains blood & lymph vessels, nerves,
urine-collecting structuresurine-collecting structures
KIDNEY ANATOMYKIDNEY ANATOMY
Renal parenchymaRenal parenchyma Glandular tissueGlandular tissue Forms urineForms urine Two zonesTwo zones
Outer cortexOuter cortex Inner medullaInner medulla
KIDNEY ANATOMYKIDNEY ANATOMY
Renal parenchymaRenal parenchyma Renal pyramidsRenal pyramids
Extensions of cortex (renal columns) divide medulla Extensions of cortex (renal columns) divide medulla into 6 – 10 into 6 – 10 renal pyramidsrenal pyramids
Pyramid + overlying cortex = LobePyramid + overlying cortex = Lobe Point of pyramid = Papilla Point of pyramid = Papilla Papilla nested in cup (minor calyx)Papilla nested in cup (minor calyx) 2 – 3 minor calices 2 – 3 minor calices Major calyx Major calyx 2 – 3 major calices 2 – 3 major calices Renal pelvis Renal pelvis Renal pelvis Renal pelvis Ureter Ureter
KIDNEY ANATOMY: NEPHRONSKIDNEY ANATOMY: NEPHRONS
NephronsNephrons Functional units of kidneyFunctional units of kidney ~1.2 million per kidney~1.2 million per kidney Three main partsThree main parts
Blood vesselsBlood vessels Renal corpuscleRenal corpuscle Renal tubuleRenal tubule
NEPHRONSNEPHRONS
Blood vessels servicing kidneyBlood vessels servicing kidney Supplied by renal arterySupplied by renal artery
~21% or cardiac output~21% or cardiac output (Mass in only ~ 0.4%)(Mass in only ~ 0.4%) Afferent arteriolesAfferent arterioles Capillary cluster (glomerulus)Capillary cluster (glomerulus)
NEPHRONSNEPHRONS
Blood vessels servicing kidneyBlood vessels servicing kidney GlomerulusGlomerulus
Fenestrated capillariesFenestrated capillaries Capillary filtration in glomerulus initiates urine Capillary filtration in glomerulus initiates urine
productionproduction Filtrate lacks cells & proteinsFiltrate lacks cells & proteins Drained by efferent arterioleDrained by efferent arteriole Peritubular capillariesPeritubular capillaries Renal veinRenal vein
NEPHRONSNEPHRONS
Renal corpuscleRenal corpuscle Glomerulus plus capsuleGlomerulus plus capsule Glomerulus enclosed in two-layered glomerular Glomerulus enclosed in two-layered glomerular
capsulecapsule ““Bowman’s capsule”Bowman’s capsule”
Fluid filters from glomerular capillariesFluid filters from glomerular capillaries ““Glomerular filtrate”Glomerular filtrate”
Fluid collects in capsular spaceFluid collects in capsular space Fluid flows into renal tubuleFluid flows into renal tubule
NEPHRONSNEPHRONS
Renal tubuleRenal tubule Leads from glomerular capsuleLeads from glomerular capsule Ends at tip of medullary pyramidEnds at tip of medullary pyramid ~3 cm long~3 cm long Four major regionsFour major regions
Proximal convoluted tubuleProximal convoluted tubule Nephron loopNephron loop Distal convoluted tubuleDistal convoluted tubule Collecting ductCollecting duct
NEPHRONSNEPHRONS
Renal tubuleRenal tubule Proximal convoluted tubule (PCT)Proximal convoluted tubule (PCT) Arises from glomerular capsuleArises from glomerular capsule Longest, most coiled regionLongest, most coiled region Prominent microvilliProminent microvilli
Function in absorptionFunction in absorption Much contact with peritubular capillariesMuch contact with peritubular capillaries
NEPHRONSNEPHRONS
Renal tubuleRenal tubule Nephron loop (“Loop of Henle”)Nephron loop (“Loop of Henle”) ““U” – shaped, distal to PCTU” – shaped, distal to PCT Descending and ascending limbsDescending and ascending limbs Thick segmentsThick segments
Active transport of saltsActive transport of salts High metabolism, many mitochondriaHigh metabolism, many mitochondria
Thin segmentsThin segments Permeable to waterPermeable to water Low metabolism Low metabolism
NEPHRONSNEPHRONS
Renal tubuleRenal tubule Distal convoluted tubule (DCT)Distal convoluted tubule (DCT) Coiled, distal to nephron loopCoiled, distal to nephron loop Shorter than PCTShorter than PCT Less coiled than PCTLess coiled than PCT Very few microvilliVery few microvilli Contacts afferent and efferent arterioles Contacts afferent and efferent arterioles
(regulation imparted)(regulation imparted) Contact with peritubular capillariesContact with peritubular capillaries
NEPHRONSNEPHRONS
Renal tubulesRenal tubules Collecting ductCollecting duct DCTs of several nephrons empty into a DCTs of several nephrons empty into a
collecting ductcollecting duct Passes into medullaPasses into medulla Several merge into papillary duct (~30 per Several merge into papillary duct (~30 per
papilla)papilla) Drain into minor calyxDrain into minor calyx
URINE FORMATIONURINE FORMATION
OverviewOverview Blood plasma Blood plasma Urine Urine Four stepsFour steps
Glomerular filtrationGlomerular filtration Tubular reabsorptionTubular reabsorption Tubular secretionTubular secretion Water conservationWater conservation
URINE STORAGEURINE STORAGE
UretersUreters Carry urine from kidneys to urinary bladder Carry urine from kidneys to urinary bladder
via peristalsisvia peristalsis Rhythmic contraction of smooth muscleRhythmic contraction of smooth muscle
Enter bladder from belowEnter bladder from below Pressure from full bladder compresses Pressure from full bladder compresses
ureters and prevents backflowureters and prevents backflow
URINE STORAGEURINE STORAGE
UretersUreters Small diameterSmall diameter Easily obstructed or injured by kidney Easily obstructed or injured by kidney
stones (renal calculi)stones (renal calculi)
URINE STORAGEURINE STORAGE
Urinary bladderUrinary bladder Muscular sacMuscular sac Wrinkles termed rugaeWrinkles termed rugae Openings of ureters common site for Openings of ureters common site for
bladder infectionbladder infection
URINE ELIMINATIONURINE ELIMINATION
UrethraUrethra Conveys urine from bodyConveys urine from body Internal urethral sphincterInternal urethral sphincter
Retains urine in bladderRetains urine in bladder Smooth muscle, involuntarySmooth muscle, involuntary
External urethral sphincterExternal urethral sphincter Provides voluntary control over voiding of urineProvides voluntary control over voiding of urine
URINE ELIMINATIONURINE ELIMINATION
UrethraUrethra 3 – 4 cm long in females3 – 4 cm long in females
Bound by connective tissue to anterior wall of Bound by connective tissue to anterior wall of vaginavagina
Urethral orifice exits body between vaginal Urethral orifice exits body between vaginal orifice and clitorisorifice and clitoris
URINE ELIMINATIONURINE ELIMINATION
UrethraUrethra ~18 cm long in males~18 cm long in males
Prostatic urethraProstatic urethra• ~2.5 cm long, urinary bladder ~2.5 cm long, urinary bladder prostate prostate
Membranous urethraMembranous urethra• ~0.5 cm, passes through floor of pelvic cavity~0.5 cm, passes through floor of pelvic cavity
Penile urethraPenile urethra• ~15 cm long, passes through penis~15 cm long, passes through penis
URINE ELIMINATIONURINE ELIMINATION
Urination (micturition)Urination (micturition) ~200 ml of urine held~200 ml of urine held Distension initiates desire to voidDistension initiates desire to void Internal sphincter relaxes involuntarilyInternal sphincter relaxes involuntarily
Smooth muscleSmooth muscle External sphincter voluntarily relaxesExternal sphincter voluntarily relaxes
Skeletal muscleSkeletal muscle Poor control in infantsPoor control in infants
Bladder muscle contractsBladder muscle contracts Urine forces through urethraUrine forces through urethra
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