© 2015 pearson education, inc. figure 26-1 an introduction to the urinary system. kidney ureter...

© 2015 Pearson Education, Inc.

Figure 26-1 An Introduction to the Urinary System.

Kidney

Ureter

Urinary bladder

Urethra

Organs of the Urinary System

Produces urine

Transports urinetoward theurinary bladder

Temporarily storesurine priorto urination

Conducts urine toexterior; in males,it also transports semen

Anterior viewp. 973


Figure 26-2a The Position of the Kidneys.

Adrenal gland

Diaphragm

11th and 12th ribs

Left kidney

L1 vertebra

Ureter

Inferior vena cava

Iliac crest

Aorta

Urinary bladder

Urethra

A posterior view of the trunk

Right kidney

Renal arteryand vein

ap. 974


Figure 26-4a The Structure of the Kidney.

Ureter

Inner layer offibrous capsule

Hilum

Renal pelvis

Renal sinus

Adipose tissuein renal sinus

Renal papilla

Minor calyx

Renal pyramid

Fibrous capsule

Major calyx

Connection tominor calyx

Renal medulla

Renal columns

Renal cortex

Kidney lobe

a A diagrammatic view of a frontalsection through the left kidneyp. 976


Figure 26-5a The Blood Supply to the Kidneys.

Interlobararteries

Interlobarveins

Corticalradiate

arteries

Corticalradiate

veins

Arcuateveins

Cortex

Medulla

Arcuatearteries

Renalartery

Renalvein

Adrenalartery

Segmentalartery

a A sectional view, showing majorarteries and veins

p. 977


Figure 26-5b The Blood Supply to the Kidneys.

Interlobar artery

Interlobar vein

Cortical radiate artery

Cortical radiate vein

Corticalnephron

Juxtamedullarynephron

Afferentarterioles

Arcuate vein

Arcuate artery

Renalpyramid

Glomerulus

Minor calyx

b Circulation in a single kidney lobep. 977


Figure 26-5c The Blood Supply to the Kidneys.

Renal arteryRenal vein

Segmental arteries

Interlobar arteries

Arcuate arteries

Cortical radiate arteries

Afferent arteriolesVenules

Cortical radiate veins

Arcuate veins

Interlobar veins

Efferentarteriole

GlomerulusPeritubularcapillaries

NEPHRONS

A flowchart of renal circulationcp. 977


Figure 26-7a The Locations and Structures of Cortical and Juxtamedullary Nephrons.

Medulla

Corticalnephron

Juxtamedullarynephron

Cortex

Collectingduct

Papillaryduct

Minor calyx

Renalpapilla

The general appearance and locationof nephrons in the kidneys

ap. 979



© 2

015

Pear

son

Educ

ation

, Inc

.



Figure 26-6 The Functional Anatomy of a Representative Nephron and the Collecting System (Part 1 of 2).

NEPHRON

Proximal convoluted tubule Distal convoluted tubule

• Reabsorption of water, ions,and all organic nutrients

• Secretion of ions, acids, drugs, toxins• Variable reabsorption of water, sodium ions,

and calcium ions (under hormonal control)

• Production of filtrate

Renal corpuscle

Nephron loop

Squamous cells

Cuboidal cellswith abundantmicrovilli

Mitochondria

Cuboidal cellswith few microvilli

Renaltubule

Efferent arteriole

Afferent arteriole

Glomerulus

Glomerular capsule

Capsular spaceDescending

limb ofloop begins

Ascendinglimb ofloop ends

Thickascendinglimb

Thindescending

limb

Descending limb Further reabsorptionof water

Ascending limbReabsorption ofsodium andchloride ions

Squamous cells

Low cuboidal cells

KEY

Filtrate

Water reabsorption

Variable water reabsorption

Solute reabsorptionor secretion

Variable solute reabsorption or secretionp. 978



COLLECTING SYSTEM

KEY

Filtrate

Water reabsorption



Variable solute reabsorption or secretion

Minorcalyx

Columnar cells

• Delivery of urine to minor calyx

Papillary duct

• Variable reabsorption of waterand reabsorption or secretion ofsodium, potassium, hydrogen,and bicarbonate ions

Intercalatedcell

Principal cell

Collecting duct

p. 978


Figure 26-8a The Renal Corpuscle.

Efferent arteriole

Macula densa

Afferent arteriole

Distal convolutedtubule

Juxtaglomerularcells

Juxtaglomerularcomplex

Capsularspace

Glomerularcapillary

Capsularepithelium

Visceralepithelium(podocyte)

Glomerular capsule

Proximalconvoluted

tubule

Important structural features of a renal corpuscle.ap. 981


Figure 26-8b The Renal Corpuscle.

Pores

Podocyte

Dense layer

Capsular space

Pedicels

Fenestratedendothelium

Filtrationslits

Podocytenucleus

Capillaryendothelialcell

Mesangialcell

Capsularepithelium

RBC

This cross section through a portion ofthe glomerulus shows the components ofthe filtration membrane of the nephron.

b

Filtrationmembrane

p. 981



NEPHRON

Proximal convoluted tubule Distal convoluted tubule

• Reabsorption of water, ions,and all organic nutrients

• Secretion of ions, acids, drugs, toxins• Variable reabsorption of water, sodium ions,

and calcium ions (under hormonal control)

• Production of filtrate

Renal corpuscle

Nephron loop

Squamous cells

Cuboidal cellswith abundantmicrovilli

Mitochondria

Cuboidal cellswith few microvilli

Renaltubule

Efferent arteriole

Afferent arteriole

Glomerulus

Glomerular capsule

Capsular spaceDescending

limb ofloop begins

Ascendinglimb ofloop ends

Thickascendinglimb

Thindescending

limb

Descending limb Further reabsorptionof water

Ascending limbReabsorption ofsodium andchloride ions

Squamous cells

Low cuboidal cells

KEY

Filtrate

Water reabsorption



Variable solute reabsorption or secretionp. 978


Figure 26-10a Glomerular Filtration.

Podocyte

Glomerulus

Pore

Capillarylumen

Denselayer

Filtrationslit

Pedicels

Capsularspace

Filtrationmembrane

Efferentarteriole

Afferentarteriole

The glomerularfiltration membrane

a

p. 988


Figure 26-10b Glomerular Filtration.

Factors Controlling Glomerular Filtration

The glomerular hydrostatic pressure (GHP) is the blood pressure in the glomerular capillaries.This pressure tends to push water and solute molecules out of the plasma and into the filtrate. TheGHP, which averages 50 mm Hg, is significantly higher than capillary pressures elsewhere in thesystemic circuit, because the efferent arteriole is smaller in diameter than the afferent arteriole.

The blood colloid osmotic pressure (BCOP) tends to draw water out of thefiltrate and into the plasma; it thusopposes filtration. Over the entire lengthof the glomerular capillary bed, the BCOPaverages about 25 mm Hg.

The net filtration pressure (NFP) is thenet pressure acting across the glomerularcapillaries. It represents the sum of thehydrostatic pressures and the colloidosmotic pressures. Under normalcircumstances, the net filtration pressureis approximately 10 mm Hg. This is theaverage pressure forcing water anddissolved substances out of the glomerularcapillaries and into the capsular space.

Capsular hydrostatic pressure (CsHP) opposes GHP. CsHP, which tends to pushwater and solutes out of the filtrate and intothe plasma, results from the resistance offiltrate already present in the nephron thatmust be pushed toward the renal pelvis. Thedifference between GHP and CsHP is the nethydrostatic pressure (NHP).

Filtrate incapsular

space

Solutes

Plasmaproteins

The capsular colloid osmotic pressureis usually zero because few, if any, plasmaproteins enter the capsular space.

50

25

15

10mmHg

Net filtration pressureb p. 988


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)

© 2015 Pearson Education, Inc. p. 988


Figure 26-12 Transport Activities at the PCT (Part 1 of 2).

Lumen containingtubular fluid

Cuboidalepithelial cells

Proximalconvoluted

tubule

Glomerulus

Distalconvolutedtubule

Glomerularcapsule

Collectingduct

Nephron loop

Urine storageand elimination

KEY

Water reabsorption

Solute reabsorption

Variable solute reabsorptionor secretionp. 993


Figure 26-12 Transport Activities at the PCT (Part 2 of 2).

Cells ofproximalconvolutedtubule

Glucoseand otherorganicsolutes

Tubular fluid

Osmoticwaterflow

Peritubularfluid

Peritubularcapillary

KEY

Leak channel

Countertransport

Exchange pump

Cotransport

Diffusion

Reabsorption

Secretion

p. 988


Figure 26-13a Countercurrent Multiplication and Urine Concentration (Part 2 of 2).

Cells ofthickascendinglimb

Tubular fluid

Peritubularfluid

This plasmamembrane isimpermeableto water

Urea

KEY

Cotransport

Exchange pump

Reabsorption

Secretion

Diffusion

The mechanism of sodium and chloride ion transport involves theNa+–K+/2 Cl– carrier at the apical surface and two carriers at thebasal surface of the tubular cell: a potassium–chloride cotransportpump and a sodium–potassium exchange pump. The net result isthe transport of sodium and chloride ions into the peritubular fluid.

a

p. 995Loop of Henle


Figure 26-13b Countercurrent Multiplication and Urine Concentration.

Thindescending

limb(permeable

to water;impermeable

to solutes)

Renal medulla

Thickascending limb(impermeableto water;active solutetransport)

KEYImpermeable to water

Impermeable to solutes

Impermeable to urea;variable permeability to water

Permeable to urea

Transport of NaCl along the ascending thick limb resultsin the movement of water from the descending limb.

bp. 995


Figure 26-13c Countercurrent Multiplication and Urine Concentration.

Thin descendinglimb (permeable

to water;Impermeable

to urea)

Renalcortex

DCT andcollectingducts(impermeableto urea;variablepermeabilityto water)

Renal medulla

Papillary duct(permeable tourea)

The permeability characteristics of both the loop and the collectingduct tend to concentrate urea in the tubular fluid and in the medulla. The nephron loop, DCT, and collecting duct are impermeable tourea. As water reabsorption occurs, the urea concentrationincreases. Papillary duct permeability to urea makes up nearlyone-third of the solutes in the deepest portions of the medulla.

c

Na+

Cl–

Urea

KEY

Impermeable to water



Permeable to urea

p. 995


Figure 26-8a The Renal Corpuscle.

Efferent arteriole

Macula densa

Afferent arteriole

Distal convolutedtubule

Juxtaglomerularcells

Juxtaglomerularcomplex

Capsularspace

Glomerularcapillary

Capsularepithelium

Visceralepithelium(podocyte)

Glomerular capsule

Proximalconvoluted

tubule

Important structural features of a renal corpuscle.ap. 988


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

Proximalconvoluted

tubule

Glomerulus

Glomerularcapsule

Distalconvoluted

tubule

Collectingduct

Nephronloop


Cells ofdistalconvolutedtubule

Peritubularfluid

a

KEY

Peritubularcapillary

Tubular fluid

Sodium and chloridereabsorption along entirelength of DCT

Leak channel

Countertransport

Exchange pump

Cotransport

Diffusion

Reabsorption

SecretionAldosterone-regulated pump

The basic pattern of thereabsorption of sodium andchloride ions and the secretionof potassium ions.

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

Sodium ions arereabsorbed inexchange forpotassium ions whenthese ion pumps arestimulated byaldosterone (A).

Tubular fluid

Sodium–potassium exchange inaldosterone-sensitive portion of DCTand collecting duct

p. 998 DCT


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

Proximalconvoluted

tubule

Glomerulus

Glomerularcapsule

Distalconvoluted

tubule

Collectingduct

Nephronloop


KEY

Leak channel

Countertransport

Exchange pump

Cotransport

Diffusion

Reabsorption

Secretion

Aldosterone-regulated pump

Tubular fluid

Hydrochloricacid

Ammoniumchloride

H+ secretion and HCO3– reabsorption along entire DCT and

collecting duct

Amino aciddeamination

Sodium bicarbonate

c Hydrogen ion secretion and the acidification of urine occur by tworoutes. The central theme is the exchange of hydrogen ions in thecytosol for sodium ions in the tubular fluid, and the reabsorption ofthe bicarbonate ions generated in the process.p. 999 DCT & CD


Figure 26-15a The Effects of ADH on the DCT and Collecting Duct (Part 2 of 2).

Renal cortex

Glomerulus

PCT DCT

Solutes

Collectingduct

Renal medulla

Large volumeof dilute urine

a Tubule permeabilities and theosmotic concentration of urinewithout ADH

KEY

=Na+/Cl–

transport

=Antidiuretichormone

=Waterreabsorption

=Variable waterreabsorption

=Impermeable to solutes

= Impermeable to water

=Variable permeabilityto water

p. 1000


Figure 26-15b The Effects of ADH on the DCT and Collecting Duct (Part 2 of 2).

KEY

=Na+/Cl–

transport

=Antidiuretichormone

=Waterreabsorption

=Variable waterreabsorption

=Impermeable to solutes

= Impermeable to water

=Variable permeabilityto water

Renal cortex

Renal medulla

Small volume ofconcentrated urine

b Tubule permeabilities and the osmoticconcentration of urine with ADH p. 1000


Figure 26-13c Countercurrent Multiplication and Urine Concentration.

Thin descendinglimb (permeable

to water;Impermeable

to urea)

Renalcortex

DCT andcollectingducts(impermeableto urea;variablepermeabilityto water)

Renal medulla

Papillary duct(permeable tourea)

The permeability characteristics of both the loop and the collectingduct tend to concentrate urea in the tubular fluid and in the medulla. The nephron loop, DCT, and collecting duct are impermeable tourea. As water reabsorption occurs, the urea concentrationincreases. Papillary duct permeability to urea makes up nearlyone-third of the solutes in the deepest portions of the medulla.

c

Na+

Cl–

Urea

KEY

Impermeable to water



Permeable to urea

p. 995 CD


Figure 26-11 The Response to a Reduction in the GFR (Part 2 of 2).

Autoregulation

Immediate localresponse in thekidney

Increasedglomerularblood pressure

Dilation ofafferent arterioles

Contraction ofmesangial cells

Constriction ofefferent arterioles

HOMEOSTASISRESTORED

NormalGFR

HOMEOSTASISDISTURBED

Decreased GFRresulting in

decreased filtrateand urine

production

if sufficient

HOMEOSTASIS

Normalglomerular

filtration rate

Start

p. 991


Figure 26-11 The Response to a Reduction in the GFR (Part 1 of 2).

Renin–Angiotensin-Aldosterone System

Integrated endocrine andneural mechanisms activated

Endocrineresponse

Juxtaglomerularcomplex increasesproduction of renin

Renin in the bloodstreamtriggers formation of

angiotensin I, which is thenactivated to angiotensin II by angiotensin converting

enzyme (ACE) in the capillaries of the lungs

Angiotensin II constrictsperipheral arterioles and

further constricts theefferent arterioles

Angiotensin II triggersincreased aldosterone

secretion by theadrenal glands

Angiotensin IItriggersneural

responses

Aldosteroneincreases

Na+ retention

Increased fluidconsumption

Increased fluidretention

Constriction ofvenous reservoirs

Increasedcardiac output

Together, angiotensin IIand sympathetic activation

stimulate peripheralvasoconstriction

Increasedsympatheticmotor tone

Increased ADHproduction

Increasedstimulation ofthirst centers

HOMEOSTASISRESTORED

Increasedglomerularpressure

Increasedsystemic

bloodpressure

Increasedblood

volume

HOMEOSTASIS

Normalglomerular

filtration rate p. 991


Figure 26-16 Summary of Renal Function (Part 1 of 6).

p. 1002


Figure 26-16 Summary of Renal Function (Part 2 of 6).

p. 1003

© 2015 pearson education, inc. figure 26-1 an introduction to the urinary system. kidney ureter...

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