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CHAPTER 25The Urinary System

Copyright © 2007 by John Wiley & Sons, Inc.

Principles ofHuman Anatomy

Eleventh Edition

Principles ofHuman Anatomy

Eleventh EditionGerard J. Tortora

&

Mark T. Nielsen

Urinary System OrgansUrinary System Organsnn KidneysKidneys

nn Produce urineProduce urine

nn UretersUretersnn Pass urine from Pass urine from

kidneys to bladderkidneys to bladdernn Urinary bladderUrinary bladder

nn Storage of urineStorage of urinenn UrethraUrethra

nn Passes urine from the Passes urine from the bodybody

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Retroperitoneal KidneysRetroperitoneal Kidneys Urinary System FunctionsUrinary System Functionsnn Regulation of blood volume & compositionRegulation of blood volume & composition

nn And thereby of interstitial fluid and bodyAnd thereby of interstitial fluid and bodynn Regulation of blood pHRegulation of blood pH

nn By controlling HBy controlling H++ excretion /retention of excretion /retention of bicarbbicarbnn Regulation of blood pressureRegulation of blood pressure

nn Via the Via the reninrenin--angiotensinangiotensin--aldosteronealdosterone systemsystemnn Metabolism of:Metabolism of:

nn CaCa++++ balance (conversion of Vitamin D)balance (conversion of Vitamin D)nn RBC formation (RBC formation (erythropoetinerythropoetin secretion)secretion)nn GluconeogenesisGluconeogenesis (occurs in starvation)(occurs in starvation)

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Kidney AnatomyKidney Anatomynn Renal SinusRenal Sinus

nn Renal PelvisRenal Pelvisnn Major Calyces (2Major Calyces (2--3)3)nn Minor Calyces (8Minor Calyces (8--18)18)

nn Renal CapsuleRenal Capsulenn Renal CortexRenal Cortex

nn Renal ColumnsRenal Columnsnn Renal MedullaRenal Medulla

nn Renal PyramidsRenal Pyramids

Nephrons

n Functional unit of the kidneyn Approximately 1 million nephrons –

number constant from birthn Damaged nephrons do not regeneraten Two major types

n Cortical nephronsn Juxtamedullary nephrons

n Create the Vertical Osmotic Gradient

Major parts of the nephronn Renal corpuscle

n Glomerulusn Capillary bed

n Bowman’s capsule/glomerular capsulen Renal tubule

n Proximal convoluted tubulen Loop of Henle

n Descending limbn Ascending limb

n Distal convoluted tubule

n Nephrons connect to the collecting ducts

Major parts of the nephronMajor parts of the nephron

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26_05a26_05a Filtration Membranen Fenestrations in

endotheliumn Stops cells

n Basement membranen Stops large proteins

n Slit membrane / slit diaphragm (between pedicles)n Stops medium-sized

proteins

26_0826_08 Blood Flow in the Kidneyn Kidneys make up only 1% of total body

mass but receive 20-25% of blood flow of resting cardiac output ~ 1200 ml/min

n Our 3rd portal system is located in the kidney

n The portal vein in this case is called the efferent arteriole.n Lies between the glomerulus and the

peritubular capillaries or vasa rectan Memorize blood flow through the kidney

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Urine production

n Renal corpuscles produce 180 liters of filtrate/day

n Plasma volume would be depleted in ~ 30 minutes

n Reabsorption of most of the filtrate in the tubule

n Secretion of wastes into the tubule

3 processes in urine production

n Filtrationn Occurs in the renal corpuscle

n Reabsorption n Occurs in the renal tubule

n Secretion n Occurs in the renal tubule

Major parts of the nephronMajor parts of the nephron Uretersn Extension of the renal pelvisn 10-12” longn Retroperitonealn Stretching of filling bladder creates physiological

sphinctersn Muscularis

n Inner longitudinaln Outer circular

n Transitional epithelium

26_1026_10 Urinary Bladdern Retroperitonealn Collapsed when emptyn Average capacity ~ 800 mlsn Transitional Epitheliumn Trigone

n Smooth appearancen Frequently the sight of infection

n Detrusor musclen Inner longitudinaln Middle circularn Outer longitudinal

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Urethran Passageway for urine to leave the bladdern Internal sphincter

n Smooth musclen External sphincter

n Skeletal musclen Female – 1.5 inches

n Orifice located between the clitoris and vaginan Male - ~ 8 inches

n Prostatic urethran Membranous (intermediate ) urethran Spongy (penile) urethra

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Kidney DialysisKidney Dialysis 26_clinic_0326_clinic_03

Learning ObjectivesLearning Objectives

nn List the organs of the urinary system and List the organs of the urinary system and give general functions for eachgive general functions for each

nn Describe the major parts of the kidneyDescribe the major parts of the kidneynn Describe a nephron and list all parts and Describe a nephron and list all parts and

include where each of the 3 processes of include where each of the 3 processes of urine formation occururine formation occur

nn Describe the filtration membrane of the Describe the filtration membrane of the glomerulusglomerulus

Learning ObjectivesLearning Objectives

nn Describe the blood flow pathways within Describe the blood flow pathways within the kidneythe kidney

nn Which vessel is considered a portal vein?Which vessel is considered a portal vein?nn Discuss the anatomy and histology of the Discuss the anatomy and histology of the

ureters and the urinary bladderureters and the urinary bladdernn Discuss the differences between the male Discuss the differences between the male

and female urethraand female urethra