The Urinary System Chapter 15. Functions of the Urinary System Elimination of waste products...
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Transcript of The Urinary System Chapter 15. Functions of the Urinary System Elimination of waste products...
The Urinary SystemThe Urinary System
Chapter 15Chapter 15
Functions of the Urinary SystemFunctions of the Urinary System Elimination of waste productsElimination of waste products
Nitrogenous wastesNitrogenous wastes ToxinsToxins DrugsDrugs
Regulate aspects of homeostasisRegulate aspects of homeostasis Water balanceWater balance ElectrolytesElectrolytes Acid-base balance in the bloodAcid-base balance in the blood Blood pressureBlood pressure Red blood cell productionRed blood cell production Activation of vitamin DActivation of vitamin D
Organs of the Urinary systemOrgans of the Urinary system
KidneysKidneysUretersUretersUrinary bladderUrinary bladderUrethraUrethra
Location of the KidneysLocation of the Kidneys
Kidney is located against Kidney is located against dorsal body wall in the dorsal body wall in the bodybody
Kidneys extend from TKidneys extend from T1212
to Lto L33
The right kidney is slightly The right kidney is slightly lower than the leftlower than the left
Features and Structure of KidneyFeatures and Structure of Kidney Is dark red kidney-bean shapedIs dark red kidney-bean shaped
12 cm long, 6 cm wide, 3 cm thick12 cm long, 6 cm wide, 3 cm thick
Has medial indentationHas medial indentation called called Renal hilumRenal hilum
Several structures enter or exit Several structures enter or exit the kidney (ureters, renal blood the kidney (ureters, renal blood vessels, and nerves) at vessels, and nerves) at hilumhilum
An adrenal gland sits atop each An adrenal gland sits atop each kidneykidney
Coverings of the KidneysCoverings of the Kidneys Three layers of supportive tissue Three layers of supportive tissue
surround each kidney:surround each kidney:
Fibrous capsuleFibrous capsule Transparent fibrous capsule Transparent fibrous capsule
surrounds each kidneysurrounds each kidney
Perirenal fat capsulePerirenal fat capsule Surrounds the kidney and Surrounds the kidney and
cushions against blowscushions against blows
Renal fasciaRenal fascia Outermost capsule that helps Outermost capsule that helps
hold the kidney in place hold the kidney in place against the muscles of the against the muscles of the trunk walltrunk wall
Regions of the KidneyRegions of the Kidney
Cortex –Cortex – the light colored, the light colored, outer region outer region
Medulla –Medulla – Reddish brown Reddish brown areaarea
Has cone-shaped Has cone-shaped medullary (renal) medullary (renal) pyramids separated by pyramids separated by renal columnsrenal columns
Renal pelvis –Renal pelvis – Medial to Medial to the hilusthe hilus
Flat basin like cavityFlat basin like cavity
Regions of the KidneyRegions of the Kidney
Calyces –Calyces – large branches large branches of the of the renal pelvisrenal pelvis
Collect urine draining from Collect urine draining from tips of tips of pyramidspyramids
Empty urine into the Empty urine into the renal renal pelvispelvis
Urine flows through the Urine flows through the renal pelvis to ureter and renal pelvis to ureter and then to the bladderthen to the bladder
Blood Flow in the KidneysBlood Flow in the Kidneys Kidneys continuously cleanse Kidneys continuously cleanse
the bloodthe blood One-quarter of the total blood One-quarter of the total blood
supply of the body passes supply of the body passes through the kidneys each minutethrough the kidneys each minute
Renal artery provides each Renal artery provides each kidney with arterial blood supplykidney with arterial blood supply
Venous blood drain from kidney Venous blood drain from kidney takes place via Renal veintakes place via Renal vein
NephronNephron Each kidney contains more Each kidney contains more
than a million tiny structures – than a million tiny structures – NephronsNephrons
Nephrons -Nephrons - The structural and The structural and functional units of the kidneysfunctional units of the kidneys
Responsible for forming urineResponsible for forming urine
Main structures of the nephronMain structures of the nephron
GlomerulusGlomerulus Renal tubuleRenal tubule
GlomerulusGlomerulus Is a knot of capillariesIs a knot of capillaries
Attached to Attached to arterioles on both sides arterioles on both sides (maintains (maintains high pressure)high pressure)
Large afferent Large afferent arteriolearteriole
Narrow efferent Narrow efferent arteriolearteriole
GlomerulusGlomerulus Capillaries are covered Capillaries are covered
with with Octopus –like cells called Octopus –like cells called
podocytes podocytes Forms porous membrane Forms porous membrane
around glomerulusaround glomerulus
Cup-shaped, First part of Cup-shaped, First part of renal tubule surrounds the renal tubule surrounds the glomerulus known as glomerulus known as Glomerular (Glomerular (Bowman’sBowman’s) ) capsulecapsule
NephronNephron Renal TubuleRenal Tubule
Renal tubule extends from Renal tubule extends from glomerular capsule and ends glomerular capsule and ends at the collecting ductat the collecting duct
Proximal convoluted Proximal convoluted tubule (PCT)tubule (PCT)
Loop of HenleLoop of Henle
Distal convoluted tubule Distal convoluted tubule (DCT)(DCT)
Types of NephronsTypes of Nephrons Cortical nephronsCortical nephrons
Located entirely in the Located entirely in the cortexcortex
Includes most Includes most nephronsnephrons
Juxtamedullary nephronsJuxtamedullary nephrons Found at the boundary Found at the boundary
of the cortex and of the cortex and medullamedulla
Collecting DuctCollecting Duct
Receives urine from Receives urine from many nephronsmany nephrons
Run through the Run through the medullary pyramidsmedullary pyramids
Deliver urine into the Deliver urine into the calyces and renal calyces and renal pelvispelvis
Each and every Nephron is associated Each and every Nephron is associated with two capillary bedswith two capillary bedsGlomerulusGlomerulusPeritubular capillary bedPeritubular capillary bed
Nephron AnatomyNephron Anatomy
GlomerulusGlomerulus Glomerulus is fed and drained by Glomerulus is fed and drained by
arteriolesarterioles
Afferent arteriole—Afferent arteriole— arises from a arises from a cortical radiate artery and feeds the cortical radiate artery and feeds the glomerulusglomerulus
Efferent arteriole—Efferent arteriole— receives blood receives blood that has passed through the that has passed through the glomerulusglomerulus
Specialized for filtrationSpecialized for filtration
BP in glomerular capillaries is much BP in glomerular capillaries is much higher than other capillarieshigher than other capillaries
High pressure forces fluid and solutes High pressure forces fluid and solutes (smaller than proteins) out of blood and (smaller than proteins) out of blood and into the glomerular capsuleinto the glomerular capsule
Most of the filtrate from renal tubule is Most of the filtrate from renal tubule is absorbed by peritubular capillary beds absorbed by peritubular capillary beds and returned to bloodand returned to blood
Peritubular CapillariesPeritubular Capillaries
Arise from Arise from efferent arterioleefferent arteriole of of the glomerulus, which drains the glomerulus, which drains the glomerulusthe glomerulus
low pressure capillarieslow pressure capillaries
Adapted for absorption instead Adapted for absorption instead of filtrationof filtration
Cling close to the renal tubule to Cling close to the renal tubule to reabsorb (reclaim) some solutes reabsorb (reclaim) some solutes and waterand water
Drains into the veinsDrains into the veins
Urine Formation ProcessesUrine Formation Processes
Three processes:Three processes:Glomerular FiltrationGlomerular FiltrationTubular ReabsorptionTubular ReabsorptionTubular SecretionTubular Secretion
Glomerular FiltrationGlomerular Filtration Nonselective passive processNonselective passive process
Fluid passes from blood into Fluid passes from blood into glomerular capsule (part of glomerular capsule (part of renal tubule)renal tubule)
Fluid (Water and solutes smaller Fluid (Water and solutes smaller than proteins) than proteins) are forced through capillary are forced through capillary
wallswalls
Blood cells and proteins cannot Blood cells and proteins cannot pass out to the capillariespass out to the capillaries
Filtrate is collected in the Filtrate is collected in the glomerular capsule glomerular capsule
and leaves via the renal tubuleand leaves via the renal tubule
Tubular ReabsorptionTubular Reabsorption Besides wastes and excess ions ,Filtrate Besides wastes and excess ions ,Filtrate
contains many useful substances, which is contains many useful substances, which is returned to blood via absorptionreturned to blood via absorption
Reabsorption begins when filtrate enters Reabsorption begins when filtrate enters proximal convoluted tubule from glomerulusproximal convoluted tubule from glomerulus
The peritubular capillaries reabsorb useful The peritubular capillaries reabsorb useful substancessubstances WaterWater GlucoseGlucose Amino acidsAmino acids IonsIons
Some reabsorption is passive, most is activeSome reabsorption is passive, most is active
Most reabsorption occurs in the proximal Most reabsorption occurs in the proximal convoluted tubuleconvoluted tubule
Materials not reabsorbedMaterials not reabsorbedNitrogenous waste productsNitrogenous waste products
Urea—Urea— protein breakdown protein breakdownUric acid—Uric acid— nucleic acid breakdown nucleic acid breakdownCreatinine—Creatinine— associated with creatine metabolism associated with creatine metabolism
in musclesin muscles
Excreted through the urineExcreted through the urine
ReabsorptionReabsorption
Tubular SecretionTubular Secretion
Some materials move from Some materials move from the peritubular capillaries the peritubular capillaries
into the renal tubules filtrate into the renal tubules filtrate to be eliminated in urine, to be eliminated in urine, such assuch as
Hydrogen and potassium Hydrogen and potassium ionsions
CreatinineCreatinine
Materials left in the renal Materials left in the renal tubule move toward the tubule move toward the ureterureter
Characteristics of UrineCharacteristics of Urine In 24 hours, about 1.0 to 1.8 liters of urine are producedIn 24 hours, about 1.0 to 1.8 liters of urine are produced
Yellow color due to the pigment urochrome (from the destruction Yellow color due to the pigment urochrome (from the destruction of hemoglobin) and solutesof hemoglobin) and solutes
SterileSterile
Slightly aromaticSlightly aromatic
Normal pH of around 6Normal pH of around 6
Specific gravity of 1.001 to 1.035Specific gravity of 1.001 to 1.035
Solutes normally found in urineSolutes normally found in urineSodium and potassium ionsSodium and potassium ionsUrea, uric acid, creatinineUrea, uric acid, creatinineAmmoniaAmmoniaBicarbonate ionsBicarbonate ions
Characteristics of UrineCharacteristics of Urine
Solutes NOT normally found in urineSolutes NOT normally found in urineGlucoseGlucoseBlood proteinsBlood proteinsRed blood cellsRed blood cellsHemoglobinHemoglobinWhite blood cells (pus)White blood cells (pus)BileBile
Characteristics of UrineCharacteristics of Urine
UretersUreters Slender tubes attaching the Slender tubes attaching the
kidney to the bladderkidney to the bladder Superior end of ureter is Superior end of ureter is
continuous with the renal pelviscontinuous with the renal pelvis Enter the posterior aspect of Enter the posterior aspect of
the bladderthe bladder
Ureters are passageways that Ureters are passageways that carry urine from kidneys to bladdercarry urine from kidneys to bladder
Propel urine into bladder by Propel urine into bladder by Peristalsis aids Peristalsis aids
Urinary BladderUrinary Bladder Smooth, collapsible, muscular sacSmooth, collapsible, muscular sac Temporarily stores urineTemporarily stores urine Trigone – three openingsTrigone – three openings
Two from the uretersTwo from the ureters One to the urethraOne to the urethra
Urinary Bladder WallUrinary Bladder Wall Bladder wall contains three layers Bladder wall contains three layers
of smooth muscle, collectively of smooth muscle, collectively known as known as detrusor muscledetrusor muscle
And its mucosa is made of And its mucosa is made of transitional epitheliumtransitional epithelium
Suited for urine storageSuited for urine storage
When bladder is empty it When bladder is empty it collapses and thrown into foldscollapses and thrown into folds
Bladder can expand significantly Bladder can expand significantly without increasing internal without increasing internal pressurepressure
Urinary Bladder CapacityUrinary Bladder Capacity
A moderately full A moderately full bladder is about 5 bladder is about 5 inches long and holds inches long and holds about 500 mL of urineabout 500 mL of urine
Capable of holding Capable of holding twice that amount of twice that amount of urineurine
UrethraUrethra Thin-walled tube that carries urine from the bladder to the outside of Thin-walled tube that carries urine from the bladder to the outside of
the body by peristalsisthe body by peristalsis Release of urine is controlled by two sphinctersRelease of urine is controlled by two sphincters
Internal urethral sphincter Internal urethral sphincter Involuntary and made of smooth muscleInvoluntary and made of smooth muscle
External urethral sphincterExternal urethral sphincter Voluntary and made of skeletal muscleVoluntary and made of skeletal muscle
Urethra Gender DifferencesUrethra Gender Differences LengthLength
Females – 3–4 cm (1 inch)Females – 3–4 cm (1 inch) Males – 20 cm (8 inches)Males – 20 cm (8 inches)
LocationLocation Females – along wall of the vaginaFemales – along wall of the vagina Males – through the prostate and penisMales – through the prostate and penis
FunctionFunction Females – only carries urineFemales – only carries urine Males – carries urine and is a passageway for sperm Males – carries urine and is a passageway for sperm
cellscells
Micturition (Voiding)Micturition (Voiding)
Is the act of emptying the bladderIs the act of emptying the bladder
Two sphincters, internal and external sphincter control Two sphincters, internal and external sphincter control the flow of urinethe flow of urine
When volume of bladder reaches around 200 mlWhen volume of bladder reaches around 200 ml
Bladder stretches and activates stretch receptorsBladder stretches and activates stretch receptors
Then impulses transmitted to spinal cordThen impulses transmitted to spinal cord
Micturition (Voiding)Micturition (Voiding)
And then back to bladder via Pelvic splanchnic nerves And then back to bladder via Pelvic splanchnic nerves
Pelvic splanchnic nerves initiate bladder to go into reflex Pelvic splanchnic nerves initiate bladder to go into reflex contractionscontractions
Urine is forced past the internal urethra sphincter and the Urine is forced past the internal urethra sphincter and the person feels the urge to voidperson feels the urge to void
The external urethral sphincter must be voluntarily The external urethral sphincter must be voluntarily relaxed to voidrelaxed to void
Kidneys have four roles in maintaining blood Kidneys have four roles in maintaining blood compositioncomposition
Excretion of nitrogen-containing wastesExcretion of nitrogen-containing wastes
Maintaining water balance of the bloodMaintaining water balance of the blood
Maintaining electrolyte balance of the bloodMaintaining electrolyte balance of the blood
Ensuring proper blood pHEnsuring proper blood pH
Fluid, Electrolyte, and Acid-Base BalanceFluid, Electrolyte, and Acid-Base Balance
Distribution of Body FluidDistribution of Body Fluid Normal amount of water in the Normal amount of water in the
human bodyhuman body Young adult females – 50%Young adult females – 50% Young adult males – 60%Young adult males – 60% Babies – 75%Babies – 75% Old age – 45%Old age – 45%
Intracellular fluidIntracellular fluid (inside cells) - (inside cells) -2/3 of body fluid2/3 of body fluid
Extracellular fluidExtracellular fluid (outside (outside cells)cells) Interstitial fluidInterstitial fluid Blood plasmaBlood plasma
Maintaining Water BalanceMaintaining Water Balance Water intake must equal water Water intake must equal water
outputoutput
Sources for water intakeSources for water intake Ingested foods and fluidsIngested foods and fluids Water produced from metabolic Water produced from metabolic
processesprocesses Thirst mechanism is the driving Thirst mechanism is the driving
force for water intakeforce for water intake
Sources for water outputSources for water output Vaporization out of the lungsVaporization out of the lungs Lost in perspirationLost in perspiration Leaves the body in the fecesLeaves the body in the feces Urine productionUrine production
Maintaining Water BalanceMaintaining Water Balance
Dilute urine is produced if water intake is Dilute urine is produced if water intake is excessiveexcessive
Less urine (concentrated) is produced if large Less urine (concentrated) is produced if large amounts of water are lostamounts of water are lost
Proper concentrations of various electrolytes Proper concentrations of various electrolytes must be present in both intracellular and must be present in both intracellular and extracellular fluidsextracellular fluids
The Link Between Water and SaltThe Link Between Water and Salt
Electrolytes: Na+, K+ Electrolytes: Na+, K+ Changes in electrolyte balance Changes in electrolyte balance
causes water to move from one compartment causes water to move from one compartment to anotherto another
Alters blood volume and blood pressureAlters blood volume and blood pressureCan impair the activity of cellsCan impair the activity of cells
Regulation of Water and Electrolyte Regulation of Water and Electrolyte Reabsorption: ADH and AldosteroneReabsorption: ADH and Aldosterone
Cells in the Cells in the kidneyskidneys and and hypothalamushypothalamus are active monitorsare active monitors
When the blood pressure and volume When the blood pressure and volume decreasedecrease
Kidney releases renin Kidney releases renin Renin acts on angiotansiogenRenin acts on angiotansiogen
to form angiotensin Ito form angiotensin I Angiotensin I is further broken toAngiotensin I is further broken to
Angiotensin IIAngiotensin II
Angiotensin II stimulates Angiotensin II stimulates VasoconstrictionVasoconstriction Release of hormones ADH and Release of hormones ADH and
aldosteronealdosterone Stimulates hypothalamus thirst Stimulates hypothalamus thirst
center to drink watercenter to drink water
Antidiuretic hormone Antidiuretic hormone (ADH) release(ADH) release
Stimulates body to Stimulates body to retain waterretain water By the kidneysBy the kidneys Increases fluid volumeIncreases fluid volume Increases blood Increases blood
pressurepressure Thus brings blood Thus brings blood
pressure and volume pressure and volume togethertogether
In addition it takes the In addition it takes the help of aldosteronehelp of aldosterone
Aldosterone regulates Aldosterone regulates sodium ion content of sodium ion content of extracellular fluidextracellular fluid
Triggered by the Triggered by the rennin-angiotensin rennin-angiotensin mechanismmechanism
Increases Na+ Increases Na+ retentionretention
Increases fluid Increases fluid retentionretention
Increases blood Increases blood volumevolume
Maintaining Acid-Base Balance Maintaining Acid-Base Balance in Bloodin Blood
Blood pH must remain between 7.35 and Blood pH must remain between 7.35 and 7.45 to maintain homeostasis7.45 to maintain homeostasis
Alkalosis – pH above 7.45Alkalosis – pH above 7.45Acidosis – pH below 7.35Acidosis – pH below 7.35
Maintaining Acid-Base Balance Maintaining Acid-Base Balance in Bloodin Blood
Most acid-base balance is maintained by Most acid-base balance is maintained by the kidneysthe kidneys
Other acid-base controlling systemsOther acid-base controlling systemsBlood buffersBlood buffersRespirationRespiration
Molecules react to prevent dramatic changes in Molecules react to prevent dramatic changes in hydrogen ion (H+) concentrationshydrogen ion (H+) concentrations
Bind to H+ when pH dropsBind to H+ when pH dropsRelease H+ when pH risesRelease H+ when pH rises
Blood BuffersBlood Buffers
Blood BuffersBlood Buffers Acids are proton (H+) donorsAcids are proton (H+) donors
Strong acids dissociate completely Strong acids dissociate completely and liberate all of their H+ in waterand liberate all of their H+ in water
Cause large change in pHCause large change in pH Weak acids, such as carbonic Weak acids, such as carbonic
acid, dissociate only partiallyacid, dissociate only partially Less effect on solution`s pHLess effect on solution`s pH Play imp. role in buffer systemPlay imp. role in buffer system
Bases are proton (H+) acceptorsBases are proton (H+) acceptors Strong bases dissociate easily in Strong bases dissociate easily in
water and tie up H+ water and tie up H+
Weak bases, such as bicarbonate Weak bases, such as bicarbonate ion and ammonia, are slower to ion and ammonia, are slower to accept H+accept H+
Three major chemical buffer systemsThree major chemical buffer systems
Bicarbonate buffer systemBicarbonate buffer systemPhosphate buffer systemPhosphate buffer systemProtein buffer systemProtein buffer system
Blood BuffersBlood Buffers
Mixture of carbonic acid (HMixture of carbonic acid (H22CO3) and sodium CO3) and sodium bicarbonate (NaHCObicarbonate (NaHCO33))
Bicarbonate ions (HCOBicarbonate ions (HCO33––) react with strong acids to ) react with strong acids to
change them to weak acidschange them to weak acids
HCl + NaHCOHCl + NaHCO33 H H22COCO33 + NaCl + NaCl
strong acid weak base weak acid saltstrong acid weak base weak acid salt
Bicarbonate Buffer SystemBicarbonate Buffer System
Carbonic acid dissociates in the presence of a strong Carbonic acid dissociates in the presence of a strong base to form a weak base and waterbase to form a weak base and water
NaOH + H2CONaOH + H2CO33 NaHCO NaHCO33 + H + H22OO
strong base weak acid weak base waterstrong base weak acid weak base water
Bicarbonate Buffer SystemBicarbonate Buffer System
Carbon dioxide in the blood is converted to bicarbonate ion and Carbon dioxide in the blood is converted to bicarbonate ion and transported in the plasmatransported in the plasma
Increase in carbon dioxide produces more carbonic acidIncrease in carbon dioxide produces more carbonic acid
And Increases in hydrogen ion concentration produces more And Increases in hydrogen ion concentration produces more carbonic acidcarbonic acid
Excess hydrogen ion can be blown off with the release of carbon Excess hydrogen ion can be blown off with the release of carbon dioxide from the lungs by increasing the breathing ratedioxide from the lungs by increasing the breathing rate
COCO22 + H + H22O HO H22COCO3 3 H H++ + HCO + HCO33--
Respiratory rate can rise and fall depending on changing blood pHRespiratory rate can rise and fall depending on changing blood pH
Respiratory System Controls of Respiratory System Controls of Acid-Base BalanceAcid-Base Balance
Excrete bicarbonate ions if neededExcrete bicarbonate ions if needed
Conserve (reabsorb) or generate new bicarbonate ions if neededConserve (reabsorb) or generate new bicarbonate ions if needed
When blood pH risesWhen blood pH rises
Bicarbonate ions are excreted Bicarbonate ions are excreted Hydrogen ions are retained by kidney tubulesHydrogen ions are retained by kidney tubules
When blood pH fallsWhen blood pH falls
Bicarbonate ions are reabsorbedBicarbonate ions are reabsorbed Hydrogen ions are secretedHydrogen ions are secreted
Urine pH varies from 4.5 to 8.0Urine pH varies from 4.5 to 8.0
Renal Mechanisms of Acid-Base BalanceRenal Mechanisms of Acid-Base Balance
Developmental Aspects of the Urinary Developmental Aspects of the Urinary SystemSystem
Functional kidneys are developed by the third monthFunctional kidneys are developed by the third month
Urinary system of a newbornUrinary system of a newborn Bladder is smallBladder is small Urine cannot be concentratedUrine cannot be concentrated
Control of the voluntary urethral sphincter does not start Control of the voluntary urethral sphincter does not start until age 18 monthsuntil age 18 months
Urinary infections are the only common problems before Urinary infections are the only common problems before old ageold age
There is a progressive decline in urinary functionThere is a progressive decline in urinary function
The bladder shrinks with agingThe bladder shrinks with aging