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Osmoregulation and Disposal Osmoregulation and Disposal of Metabolic Wastesof Metabolic Wastes
Chapter 47Chapter 47
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Learning Objective 1Learning Objective 1
• How do the processes of How do the processes of osmoregulationosmoregulation and and excretionexcretion contribute to fluid and contribute to fluid and electrolyte homeostasis?electrolyte homeostasis?
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Fluid-Electrolyte HomeostasisFluid-Electrolyte Homeostasis
• OsmoregulationOsmoregulation• active regulation of osmotic pressure of body active regulation of osmotic pressure of body
fluids fluids • maintains fluid and electrolyte homeostasis maintains fluid and electrolyte homeostasis
• ExcretionExcretion • process of ridding body of metabolic wastesprocess of ridding body of metabolic wastes
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Learning Objective 2Learning Objective 2
• Contrast the benefits and costs of Contrast the benefits and costs of excreting excreting ammoniaammonia, , uric aciduric acid, or , or ureaurea
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Nitrogenous WastesNitrogenous Wastes
• AmmoniaAmmonia (toxic) (toxic)• excreted mainly by aquatic animalsexcreted mainly by aquatic animals
• UreaUrea (less toxic) (less toxic)• synthesis requires energy synthesis requires energy • excretion requires water excretion requires water
• Uric acid Uric acid (less toxic)(less toxic)• excreted as semisolid paste (conserves water) excreted as semisolid paste (conserves water)
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Nitrogenous Nitrogenous WastesWastes
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Fig. 47-1, p. 1013
Amino acids Nucleic acids
Deamination
Ammonia Keto acids Purines
Urea cycle 15 steps
Ammonia Urea Uric acid
More energy needed to produce
More water needed to excrete
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Stepped Art
Fig. 47-1, p. 1013
Amino acids
Deamination
Ammonia Keto acids
Nucleic acids
Purines
Urea cycle 15 steps
Ammonia Urea Uric acid
More energy needed to produce
More water needed to excrete
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Learning Objective 3Learning Objective 3
• Compare Compare osmoconformersosmoconformers and and osmoregulatorsosmoregulators
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OsmoconformersOsmoconformers
• Most marine invertebrates Most marine invertebrates
• Salt concentration of body fluids varies Salt concentration of body fluids varies with changes in sea water with changes in sea water
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OsmoregulatorsOsmoregulators
• Some marine invertebratesSome marine invertebrates• especially in coastal habitats especially in coastal habitats
• Maintain optimal salt concentration despite Maintain optimal salt concentration despite changes in salinity of surroundingschanges in salinity of surroundings
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KEY CONCEPTSKEY CONCEPTS
• Osmoregulation is the process by which Osmoregulation is the process by which organisms control the concentration of organisms control the concentration of water and salt in the body so that their water and salt in the body so that their body fluids do not become too dilute or too body fluids do not become too dilute or too concentratedconcentrated
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Learning Objective 4Learning Objective 4
• Describe Describe protonephridiaprotonephridia, , metanephridiametanephridia, , and and Malpighian tubulesMalpighian tubules
• Compare their functionsCompare their functions
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Nephridial OrgansNephridial Organs
• Help maintain homeostasisHelp maintain homeostasis• by regulating concentration of body fluidsby regulating concentration of body fluids• osmoregulation osmoregulation • excretion of metabolic wastes excretion of metabolic wastes
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ProtonephridiaProtonephridia
• Tubules with no internal openingsTubules with no internal openings• in flatworms and nemerteans in flatworms and nemerteans
• Interstitial fluid enters blind endsInterstitial fluid enters blind ends• flame cellsflame cells (cells with brushes of cilia) (cells with brushes of cilia)•
• Cilia propel fluid through tubulesCilia propel fluid through tubules
• Excess fluid exits through nephridioporesExcess fluid exits through nephridiopores
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ProtonephridiaProtonephridia
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Fig. 47-2ab, p. 1014
Flame cells
Protonephridial network
Nephridiopores
Excretory tubule
Flatworm
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Fig. 47-2c, p. 1014
Nucleus
Cytoplasm
Cilia (“flame”)
Movement of interstitial fluid
Excretory tubule
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MetanephridiaMetanephridia
• Tubules open at both endsTubules open at both ends• in most annelids and mollusks in most annelids and mollusks
• Fluid from coelom moves through tubuleFluid from coelom moves through tubule• needed materials reabsorbed by capillaries needed materials reabsorbed by capillaries
• Urine exits body through nephridioporesUrine exits body through nephridiopores• contains wastescontains wastes
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MetanephridiaMetanephridia
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Fig. 47-3, p. 1014
Tubule
AnteriorPosterior
Gut
Funnel
Septum Nephridiopore Capillary network
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Malpighian Tubules 1Malpighian Tubules 1
• Extensions of insect gut wallExtensions of insect gut wall• blind ends lie in hemocoel blind ends lie in hemocoel
• Tubule cells actively transport uric acid Tubule cells actively transport uric acid from hemolymph into tubulefrom hemolymph into tubule
• water follows by diffusion water follows by diffusion
• Contents of tubule pass into gut Contents of tubule pass into gut
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Malpighian Tubules 2Malpighian Tubules 2
• Water and some solutes reabsorbed in Water and some solutes reabsorbed in rectum rectum
• Malpighian tubules effectively conserve Malpighian tubules effectively conserve water water
• contribute to success of insects as terrestrial contribute to success of insects as terrestrial animalsanimals
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Malpighian TubulesMalpighian Tubules
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Fig. 47-4, p. 1014
Gut Malpighian tubules
Waste
HindgutRectum
Midgut
Water and needed ions
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KEY CONCEPTSKEY CONCEPTS
• Excretory systems have evolved that Excretory systems have evolved that function in both osmoregulation and in function in both osmoregulation and in disposal of metabolic wastesdisposal of metabolic wastes
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Learning Objective 5Learning Objective 5
• Relate the function of the vertebrate Relate the function of the vertebrate kidneykidney to the success of vertebrates in a to the success of vertebrates in a wide variety of habitatswide variety of habitats
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The VertebrateThe Vertebrate KidneyKidney
• Excretes nitrogenous wastesExcretes nitrogenous wastes
• Helps maintain fluid balance by adjusting Helps maintain fluid balance by adjusting salt and water content of urine salt and water content of urine
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Adaptation to HabitatsAdaptation to Habitats
• Freshwater, marine, terrestrial habitatsFreshwater, marine, terrestrial habitats• different problems for maintaining internal different problems for maintaining internal
fluid balance, excretion of nitrogenous wastes fluid balance, excretion of nitrogenous wastes
• Structure and function of vertebrate kidneyStructure and function of vertebrate kidney• adapted to various osmotic challenges of adapted to various osmotic challenges of
different habitatsdifferent habitats
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KEY CONCEPTSKEY CONCEPTS
• The vertebrate kidney maintains water and The vertebrate kidney maintains water and electrolyte balance and excretes metabolic electrolyte balance and excretes metabolic wasteswastes
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Learning Objective 6Learning Objective 6
• Compare adaptations for Compare adaptations for osmoregulationosmoregulation in freshwater fishes, marine bony fishes, in freshwater fishes, marine bony fishes, sharks, marine mammals, and terrestrial sharks, marine mammals, and terrestrial vertebratesvertebrates
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Freshwater Freshwater FishesFishes
• Take in water Take in water osmoticallyosmotically
• excrete large volume excrete large volume of hypotonic urineof hypotonic urine
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Fig. 47-5a, p. 1015
Loses salt by diffusionWater gain by osmosis
Drinks no
water
Large volume of hypotonic urine
Salt uptake by gills
Kidney with large glomeruli
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Marine Bony Fishes Marine Bony Fishes
• Lose water osmotically Lose water osmotically
• Compensate by drinking sea water and Compensate by drinking sea water and excreting salt through their gillsexcreting salt through their gills
• Produce only a small volume of isotonic Produce only a small volume of isotonic urine urine
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Fig. 47-5b, p. 1015
Gains salts by diffusionWater loss by
osmosis
Drinks salt
water
Small volume of isotonic urineSalt excreted
through gillsKidney with small or
no glomeruli
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Sharks and Other Marine Sharks and Other Marine Cartilaginous FishesCartilaginous Fishes
• Retain large amounts of ureaRetain large amounts of urea• allows them to take in water osmotically allows them to take in water osmotically
through their gills through their gills
• Excrete large volume of hypotonic urine Excrete large volume of hypotonic urine
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Fig. 47-5c, p. 1015
Water gain by osmosis
Salts diffuse in through gills
Salt-excreting gland
Some salt water swallowed with
foodKidney with large
glomeruli—reabsorbs urea
Large volume of hypotonic urine
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Marine MammalsMarine Mammals
• Ingest sea water with their food Ingest sea water with their food • produce concentrated urineproduce concentrated urine
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Terrestrial VertebratesTerrestrial Vertebrates
• Must conserve water Must conserve water • adaptations include efficient kidneysadaptations include efficient kidneys
• EndothermsEndotherms• have a high metabolic rate have a high metabolic rate • produce large volume of nitrogenous wastes produce large volume of nitrogenous wastes
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Fig. 47-6b, p. 1016
LIVER ALL CELLS
Wastes produced
Hemoglobin breakdown
Breakdown of nucleic acids Cellular respiration
Deamination of amino acids
Uric acid
WastesBile pigments Water Carbon dioxide
Urea
Organs of excretion
KIDNEY DIGESTIVE SYSTEM
SKIN LUNGS
Exhaled air containing water vapor and carbon
dioxide
Excretion Urine Feces Sweat
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KEY CONCEPTSKEY CONCEPTS
• Freshwater, marine, and terrestrial Freshwater, marine, and terrestrial animals have different adaptations to meet animals have different adaptations to meet the challenges of these diverse the challenges of these diverse environmentsenvironments
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Learning Objective 7Learning Objective 7
• Describe (or label on a diagram) the Describe (or label on a diagram) the organs of the organs of the mammalian urinary systemmammalian urinary system
• Give the functions of eachGive the functions of each
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The Urinary SystemThe Urinary System
• Principal excretory system in mammals Principal excretory system in mammals
• Mammalian kidneys produce urineMammalian kidneys produce urine• passes through passes through uretersureters • to to urinary bladderurinary bladder for storage for storage
• Urine is released from the body (urination)Urine is released from the body (urination)• through the through the urethra urethra
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Human Urinary SystemHuman Urinary System
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Fig. 47-7, p. 1017
Adrenal gland
Left renal arteryRight kidney
Right renal vein
Left kidney
Inferior vena cava Abdominal aorta
Ureteral orifices
Right and left ureters
Urinary bladder
Urethra
External urethral orifice
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Kidney Structure 1Kidney Structure 1
• Renal cortexRenal cortex• outer portion of kidneyouter portion of kidney
• Renal medullaRenal medulla • inner portion of kidneyinner portion of kidney• contains 8 to 10 contains 8 to 10 renal pyramids renal pyramids
• Renal pyramids Renal pyramids • tip of each pyramid is a tip of each pyramid is a renal papillarenal papilla
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Kidney Structure 2Kidney Structure 2
• Urine flows into Urine flows into collecting ductscollecting ducts• which empty through a which empty through a renal papillarenal papilla into the into the
renal pelvisrenal pelvis (funnel-shaped chamber) (funnel-shaped chamber)
• NephronsNephrons • functional units of kidney functional units of kidney • each kidney has more than 1 million each kidney has more than 1 million
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Internal Kidney StructureInternal Kidney Structure
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Fig. 47-8a, p. 1018
Renal pyramids (medulla)
Capsule
Renal cortex
Renal medulla
Renal artery
Renal vein
Renal pelvis
Ureter
Internal structure of the kidney.
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Fig. 47-8b, p. 1018
Juxtamedullary nephron
Distal convoluted tubule Cortical nephron
Capsule
Proximal convoluted tubule
Renal cortexGlomerulus
Bowman’s capsule
Artery and vein
Loop of Henle
Renal medulla
Collecting duct
Papilla
Juxtamedullary and cortical nephrons.
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Insert “Human kidney”Insert “Human kidney”
kidney_anatomy_v2.swfkidney_anatomy_v2.swf
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Learning Objective 8Learning Objective 8
• Describe (or label on a diagram) the Describe (or label on a diagram) the structures of a structures of a nephronnephron (including (including associated blood vessels)associated blood vessels)
• Give the functions of each structureGive the functions of each structure
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Nephron StructureNephron Structure
• Each Each nephronnephron consists of consists of • a cluster of capillaries (a cluster of capillaries (glomerulusglomerulus))• surrounded by a surrounded by a Bowman’s capsuleBowman’s capsule • that opens into a long, coiled that opens into a long, coiled renal tubulerenal tubule
• Renal tubuleRenal tubule consists of consists of • proximal convoluted tubule proximal convoluted tubule • loop of Henle loop of Henle • distal convoluted tubuledistal convoluted tubule
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Types of NephronsTypes of Nephrons
• Cortical nephronsCortical nephrons • located mostly within cortex or outer medullalocated mostly within cortex or outer medulla• have small glomeruli have small glomeruli
• Juxtamedullary nephronsJuxtamedullary nephrons • extend deep into medulla extend deep into medulla • have large glomeruli and long loops of Henlehave large glomeruli and long loops of Henle• important in concentrating urineimportant in concentrating urine
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Blood Vessels 1Blood Vessels 1
• Blood flows Blood flows • from small branches of from small branches of renal arteryrenal artery • to to afferent arteriolesafferent arterioles • to to glomerular capillariesglomerular capillaries • into an into an efferent arterioleefferent arteriole
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Blood Vessels 2Blood Vessels 2
• Efferent arterioleEfferent arteriole • delivers blood into delivers blood into peritubular capillariesperitubular capillaries that that
surround the renal tubule surround the renal tubule
• Blood leaves kidney through Blood leaves kidney through renal veinrenal vein
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Nephron StructureNephron Structure
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Fig. 47-9a, p. 1019
Proximal tubule
Bowman's capsule
Glomerulus
Efferent arteriole
Afferent arteriole
Peritubular capillaries
Distal tubule
Collecting duct
From renal artery
To renal vein
To renal pelvisLoop of
Henle
(a) Location and basic structure of a nephron.
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Fig. 47-9b, p. 1019
Distal tubule Proximal tubuleBowman's capsule
Podocyte
Glomerular capillaries
Afferent arteriole Afferent arteriole
Juxtaglomerular apparatus
Efferent arteriole
Distal tubule
(b) Cutaway view of Bowman’s capsule.
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KEY CONCEPTSKEY CONCEPTS
• The nephron is the functional unit of the The nephron is the functional unit of the vertebrate kidneyvertebrate kidney
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Learning Objective 9Learning Objective 9
• Trace a drop of filtrate from Bowman’s Trace a drop of filtrate from Bowman’s capsule to its release from the body as capsule to its release from the body as urineurine
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Urine ProductionUrine Production
• FiltrationFiltration • of plasma of plasma
• ReabsorptionReabsorption • of needed materialsof needed materials
• SecretionSecretion • of potassium, hydrogen ions into renal tubuleof potassium, hydrogen ions into renal tubule
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Urine ProductionUrine Production
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Fig. 47-10, p. 1020
REABSORPTION AND SECRETION
Proximal tubule
FILTRATION
Bowman's capsuleGlomerulus
REABSORPTION AND SECRETION REABSORPTION OF
H2O; URINE CONCENTRATED
Distal tubuleCollecting duct
CapillariesRenal arteryRenal vein To renal pelvis
Loop of Henle
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Insert “Structure of the Insert “Structure of the glomerulus”glomerulus”
glomerulus.swfglomerulus.swf
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Filtration 1Filtration 1
• Plasma filters through glomerular Plasma filters through glomerular capillaries into Bowman’s capsule capillaries into Bowman’s capsule
• Filtration membraneFiltration membrane • permeable walls of capillaries permeable walls of capillaries • filtration slitsfiltration slits between between podocytespodocytes
• PodocytesPodocytes • specialized epithelial cells specialized epithelial cells • make up inner wall of Bowman’s capsulemake up inner wall of Bowman’s capsule
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Filtration MembraneFiltration Membrane
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Fig. 47-11a, p. 1021
GlomerulusBowman's capsule
Afferent arteriole
Efferent arteriole
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Fig. 47-11b, p. 1021
Blood cells restricted from passing through Endothelial cell of
capillaryRed blood cell
Capillary pores
Nucleus
Podocyte
Filtration slits
Foot processes
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Filtration 2Filtration 2
• Filtration is nonselectiveFiltration is nonselective• small molecules become part of filtratesmall molecules become part of filtrate• glucose, other needed materials, metabolic glucose, other needed materials, metabolic
wasteswastes
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Reabsorption 1Reabsorption 1
• About 99% of filtrate is reabsorbed from About 99% of filtrate is reabsorbed from renal tubules into blood renal tubules into blood
• Highly selective processHighly selective process• returns usable materials to bloodreturns usable materials to blood• leaves wastes, excess substances to be leaves wastes, excess substances to be
excreted in the urine excreted in the urine
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Reabsorption 2Reabsorption 2
• Tubular transport maximum (Tm)Tubular transport maximum (Tm)• maximum rate at which a substance can be maximum rate at which a substance can be
reabsorbed reabsorbed
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Insert “Tubular Insert “Tubular reabsorption”reabsorption”
tubular_reabsorption_m.swftubular_reabsorption_m.swf
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SecretionSecretion
• Hydrogen ions, certain other ions, and Hydrogen ions, certain other ions, and some drugs are actively transported into some drugs are actively transported into renal tubule to become part of urinerenal tubule to become part of urine
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Water, Ion and Urea MovementWater, Ion and Urea Movement
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Fig. 47-12, p. 1022
Bowman's capsule
Proximal tubule
Distal tubuleAfferent arteriole
Efferent arteriole
Filtrate NaCl MEDULLA
NaCl CORTEX
NaClCollecting ductH2O NaCl
NaClUrea
Descending limb Ascending
limb
Loop of Henle
H2O
H2O
H2O H2O
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Urine Concentration 1Urine Concentration 1
• Depends on high concentration of salt and Depends on high concentration of salt and urea in interstitial fluid of kidney medulla urea in interstitial fluid of kidney medulla
• Concentration gradient Concentration gradient • salt most concentrated around bottom of loop salt most concentrated around bottom of loop
of Henle of Henle • maintained by salt reabsorption from various maintained by salt reabsorption from various
parts of renal tubule parts of renal tubule
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Urine Concentration 2Urine Concentration 2
• Counterflow of fluid through two limbs of Counterflow of fluid through two limbs of loop of Henleloop of Henle
• concentrates filtrate moving down concentrates filtrate moving down descending loop descending loop
• dilutes filtrate moving up ascending loopdilutes filtrate moving up ascending loop
• Water is drawn from filtrate by osmosisWater is drawn from filtrate by osmosis• as it passes through collecting ductsas it passes through collecting ducts• concentrating urine in collecting ductsconcentrating urine in collecting ducts
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Urine Concentration 3Urine Concentration 3
• Vasa rectaVasa recta• system of capillaries extending from efferent system of capillaries extending from efferent
arterioles arterioles • removes some water that diffuses from filtrate removes some water that diffuses from filtrate
into interstitial fluidinto interstitial fluid
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Urine ConcentrationUrine Concentration
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Fig. 47-13, p. 1023
Bowman's capsuleProximal tubule
Distal tubuleAfferent arteriole
300 300 100 100
200Efferent arteriole
CORTEX
Filtrate300 100 300 300
MEDULLA
400 200 400 400
600 400 600 600
600Interstitial
fluid
Collecting duct
1200 1200 1200
Loop of Henle
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UrineUrine
• A watery solution of nitrogenous wastes, A watery solution of nitrogenous wastes, excess salts, and other substances not excess salts, and other substances not needed by the bodyneeded by the body
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Watch renal processes in action Watch renal processes in action by clicking on the figures in by clicking on the figures in
ThomsonNOW.ThomsonNOW.
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Learning Objective 10Learning Objective 10
• Describe the hormonal regulation of fluid Describe the hormonal regulation of fluid and electrolyte balance by and electrolyte balance by antidiuretic antidiuretic hormone (ADH),hormone (ADH), the the renin–angiotensin– renin–angiotensin– aldosterone systemaldosterone system, and , and atrial natriuretic atrial natriuretic peptide (ANP)peptide (ANP)
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Antidiuretic Hormone (ADH)Antidiuretic Hormone (ADH)
• Posterior pituitary increases Posterior pituitary increases ADHADH release release • when body needs to conserve waterwhen body needs to conserve water• responds to increase in osmotic concentration responds to increase in osmotic concentration
of blood (caused by dehydration) of blood (caused by dehydration)
• ADH increases permeability of collecting ADH increases permeability of collecting ducts to water ducts to water
• more water is reabsorbedmore water is reabsorbed• small volume of urine is producedsmall volume of urine is produced
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Regulation by Regulation by ADH ADH
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Fig. 47-14, p. 1024
1 Fluid intake is low. Receptors in the hypothalamus
2 Blood volume decreases, and osmotic pressure increases.
Posterior pituitary
ADH secretion is inhibited.
Posterior pituitary secretes ADH.
Blood volume increases, and osmotic pressure decreases.
36 7
Collecting ductNephron
H2O
Kidney
5Water reabsorption increases.
Collecting ducts become more permeable.
4
Lower urine volume
H2OH2O
H2O
H2O
H2O
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Renin-Angiotensin-Aldosterone Renin-Angiotensin-Aldosterone Pathway 1Pathway 1
• When blood pressure decreasesWhen blood pressure decreases• juxtaglomerular apparatusjuxtaglomerular apparatus secretes secretes reninrenin
• ReninRenin (enzyme) (enzyme)• activates pathway to production of activates pathway to production of angiotensin IIangiotensin II
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Renin-Angiotensin-Aldosterone Renin-Angiotensin-Aldosterone Pathway 2Pathway 2
• Angiotensin IIAngiotensin II (hormone) (hormone) • constricts arterioles (raises blood pressure)constricts arterioles (raises blood pressure)• stimulates stimulates aldosteronealdosterone release release
• AldosteroneAldosterone (hormone) (hormone)• increases sodium reabsorption (raises blood increases sodium reabsorption (raises blood
pressure)pressure)
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Atrial Natriuretic Peptide (ANP)Atrial Natriuretic Peptide (ANP)
• When blood pressure increasesWhen blood pressure increases• ANPANP increases sodium excretion, inhibits increases sodium excretion, inhibits
aldosterone secretion aldosterone secretion • increases urine output, lowers blood pressure increases urine output, lowers blood pressure
• Renin-angiotensin-aldosterone pathway Renin-angiotensin-aldosterone pathway and atrial natriuretic peptide work and atrial natriuretic peptide work antagonistically antagonistically