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Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummingsp. 958 © 2012 Pearson Education, Inc.

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Figure 26-5c The Blood Supply to the Kidneys

A flowchart of renal circulation

Renal vein Renal artery

Segmental arteries

Interlobar arteries

Arcuate arteries

Cortical radiate arteries

Afferent arterioles

Glomerulus

Efferentarteriole

Peritubularcapillaries

Interlobar veins

Arcuate veins

Cortical radiate veins

Venules

NEPHRONS

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Figure 26-6 The Functional Anatomy of a Representative Nephron and the Collecting System

NEPHRON

Distal convoluted tubuleProximal convoluted tubule

Renal corpuscle

Nephron loop

KEY

• Secretion of ions, acids, drugs, toxins• Variable reabsorption of water, sodium ions, and calcium ions (under hormonal control)

Reabsorption of water,ions, and all

organic nutrients

Renal tubule

Capsular spaceGlomerulus

Efferent arteriole

Afferent arterioleGlomerular capsule

Production of filtrate

Descendinglimb of

loop begins

Thindescending

limb

Ascendinglimb ofloop ends

Thickascendinglimb

Descendinglimb

Ascendinglimb

Further reabsorption of water(descending limb) and both

sodium and chlorideions (ascending limb)

Filtrate

Water reabsorption

Variable water reabsorption

Solute reabsorptionor secretion

Variable solute reabsorptionor secretionp. 963

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Figure 26-10b Glomerular Filtration

Net filtration pressure

Factors Controlling Glomerular Filtration

Filtrate incapsular

space

Plasmaproteins

Solutes

50

25

15

10mmHg

Capsular colloid osmoticpressure

Capsular hydrostatic pressure (CsHP)

Net filtration pressure (NFP)

Blood colloid osmotic pressure (BCOP)

Glomerular hydrostatic pressure (GHP)

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Figure 26-12 Transport Activities at the PCT

KEY

Leak channel

Countertransport

Exchange pump

Cotransport

Diffusion

Reabsorption

Secretion

Peritubularcapillary

Peritubularfluid

Osmoticwaterflow

Glucoseand otherorganicsolutes

Cells ofproximalconvolutedtubule

Tubular fluid

Lumen containingtubular fluid

Cuboidalepithelial cells

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Figure 26-13a Countercurrent Multiplication and Concentration of Urine

The mechanism of sodium and chloride ion transport involvesthe Na–K/2 Cl carrier.

KEY

Cotransport

Exchange pump

Reabsorption

Secretion

Diffusion

This plasmamembrane isimpermeableto water

UreaTubular fluid

Peritubularfluid

Cells of thickascendinglimb

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Figure 26-13c Countercurrent Multiplication and Concentration of Urine

The permeability characteristics of both the loop and the collecting duct tend to concentrate urea in the tubular fluid and in the medulla.

Renalcortex

DCT and collecting ducts (impermeable to urea; variablepermeability towater)

Thin descendinglimb (permeable

to water;impermeable

to urea)

Papillary duct(permeable tourea)

Renal medulla Urea

Na

Cl

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Figure 26-14ab Tubular Secretion and Solute Reabsorption at the DCT

The basic pattern of thereabsorption of sodium andchloride ions and the secretion ofpotassium ions

Aldosterone-regulated reabsorptionof sodium ions, linked to the passiveloss of potassium ions

Peritubularcapillary

Peritubularfluid

Cells of distalconvolutedtubule

Sodium ions arereabsorbed inexchange forpotassium ions;these ion pumpsare stimulated byaldeosterone (A).

Tubular fluid

Sodium–potassium exchange in aldosteronesensitive portion of DCT and collecting duct

Sodium and chloride reabsorptionin entire DCT

Distalconvoluted

tubule

Glomerulus

Glomerularcapsule

Proximalconvoluted

tubule

Urine storageand elimination

Collectingduct

Nephron loop

KEY

Secretion

Reabsorption

Diffusion

Cotransport

Aldosterone-regulated pump

Exchange pump

Countertransport

Leak channel

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p. 978 DCT

p. 978 DCT

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© 2012 Pearson Education, Inc.

Figure 26-14c Tubular Secretion and Solute Reabsorption at the DCT

Distalconvoluted

tubule

Glomerulus

Glomerularcapsule

Proximalconvoluted

tubule

Urine storageand elimination

Collectingduct

Nephron loop

KEY

Secretion

Reabsorption

Diffusion

Cotransport

Aldosterone-regulated pump

Exchange pump

Countertransport

Leak channel

Sodium bicarbonate

Hydrogen ion secretion and the acidification of urine occur by tworoutes.

Amino aciddeamination

Hydrochloricacid

Ammoniumchloride

Tubular fluid

H+ secretion and HCO3- reabsorption along entire DCT and collecting duct

p. 979 DCT & CD

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Figure 26-11 The Response to a Reduction in the GFR

Autoregulation

Normalglomerular

filtration rate

HOMEOSTASIS

HOMEOSTASISRESTORED

HOMEOSTASISDISTURBED

Immediate localresponse in thekidney

Increasedglomerularblood pressure

if sufficient

Dilation ofafferent arterioles

Contraction ofmesangial cells

Constriction ofefferent arterioles

NormalGFR

Decreased GFRresulting in

decreased filtrateand urine

production

Start

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Figure 26-11 The Response to a Reduction in the GFR

Renin–Angiotensin System

Endocrineresponse

Integrated endocrine andneural mechanisms activated

Juxtaglomerularcomplex increasesproduction of renin.

Angiotensin II constrictsperipheral arterioles and

further constricts theefferent arterioles.

Renin in the bloodstreamtriggers formation of

angiotensin I, which is thenactivated to angiotensin IIby angiotensin converting

enzyme (ACE) in thecapillaries of the lungs.

Angiotensin II triggersincreased aldosterone

secretion by theadrenal glands.

Aldosteroneincreases

Na retention.HOMEOSTASIS

RESTORED

Increasedglomerularpressure

Increasedsystemic

bloodpressure

Increasedblood

volume

Increased fluidconsumption

Increased fluidretention

Constriction ofvenous reservoirs

Increasedcardiac output

Increasedstimulation ofthirst centers

Increased ADHproduction

Angiotensin IItriggersneural

responses.

Increasedsympatheticmotor tone

Together, angiotensin IIand sympathetic activation

stimulate peripheralvasoconstriction.

Normalglomerular

filtration rate

HOMEOSTASIS

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