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LECTURE PRESENTATIONS

For CAMPBELL BIOLOGY, NINTH EDITIONJane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson

© 2011 Pearson Education, Inc.

Lectures by

Erin Barley

Kathleen Fitzpatrick

Osmoregulation and Excretion

Chapter 44

How does an albatross drink salt water without ill effect?

Osmoconformers

vs.

Osmoregulators

What is the difference?

Osmotic Challenges

• Osmoconformers, consisting only of some

marine animals, are isoosmotic with their

surroundings and do not regulate their

osmolarity

• Osmoregulators expend energy to control

water uptake and loss in a hyperosmotic or

hypoosmotic environment (stenohaline and

euryhaline)

© 2011 Pearson Education, Inc.

Do I

drink

water

?

Do I

drink

water

?

Describe

my pee.

Describe my pee.

Figure 44.3

(a) Osmoregulation in a marine fish (b) Osmoregulation in a freshwater fish

Gain of waterand salt ionsfrom food

Excretionof salt ionsfrom gills

Osmotic waterloss through gillsand other partsof body surface

Gain of waterand salt ionsfrom drinkingseawater

Excretion of salt ions andsmall amounts of water inscanty urine from kidneys

Gain of waterand some ionsin food

Uptake ofsalt ionsby gills

Osmotic watergain throughgills and otherparts of bodysurface

Excretion of salt ions andlarge amounts of water indilute urine from kidneys

Key

Water

Salt

Figure 44.4 Sockeye salmon (Oncorhynchus

nerka), euryhaline osmoregulators

Water balance ina kangaroo rat(2 mL/day)

Water balance ina human(2,500 mL/day)

Ingestedin food (0.2)

Ingestedin food (750)

Ingestedin liquid(1,500)Water

gain(mL)

Waterloss(mL)

Derived frommetabolism (1.8)

Derived frommetabolism (250)

Feces (0.09)

Urine(0.45)

Feces (100)

Urine(1,500)

Evaporation (1.46) Evaporation (900)

Figure 44.6

Figure 44.UN01

Animal Inflow/Outflow Urine

Freshwaterfish. Lives inwater lessconcentratedthan body fluids; fishtends to gainwater, lose salt

Does not drink water

Salt in(active trans-port by gills)

H2O in

Salt out

Marine bony fish. Lives inwater moreconcentratedthan bodyfluids; fishtends to losewater, gain salt

Terrestrialvertebrate.Terrestrialenvironment;tends to losebody waterto air

Drinks water

Drinks water

Salt in H2O out

Salt out (activetransport by gills)

Salt in(by mouth)

H2O andsalt out

Large volume of urine

Urine is lessconcentratedthan bodyfluids

Small volumeof urine

Urine isslightly lessconcentratedthan bodyfluids

Moderatevolumeof urine

Urine ismore concentratedthan bodyfluids

Counter-current exchange in salt-excreting nasal glands

What else exhibits c-c e?

Nasal saltgland

Ducts

Nostril with saltsecretions

(a) Location of nasal glandsin a marine bird

(b) Secretorytubules

(c) Countercurrentexchange

Key

Salt movement

Blood flow

Nasal gland

Capillary

Secretory tubule

Transportepithelium

Vein Artery

Central duct

Secretory cellof transportepithelium

Lumen ofsecretorytubule

Saltions

Blood flow Salt secretion

Figure 44.8

Proteins Nucleic acids

Amino

acids

Nitrogenous

bases

—NH2

Amino groups

Most aquatic

animals, including

most bony fishes

Mammals, most

amphibians, sharks,

some bony fishes

Many reptiles

(including birds),

insects, land snails

Ammonia Urea Uric acid

Figure 44.9

Key steps

of

excretory

system

function:

an

overview.

CapillaryFiltration

Excretorytubule

Reabsorption

Secretion

Excretion

Filtra

teU

rine

2

1

3

4

Figure 44.12

Components of a

metanephridium:

Collecting tubule

Internal opening

Bladder

External opening

Coelom Capillary

network

Digestive tract

Midgut

(stomach)Malpighian

tubules

Rectum

IntestineHindgut

Salt, water, and

nitrogenous

wastes

Feces

and urine

Malpighian

tubule

To anus

Rectum

Reabsorption

HEMOLYMPH

Figure 44.13

Figure 44.14-a

Excretory Organs Kidney Structure Nephron Types

Posteriorvena cava

Renalarteryand vein

Aorta

Ureter

Urinarybladder

Urethra

Kidney

Renalcortex

Renalmedulla

Renal artery

Renal vein

Ureter

Cortical nephron

Juxtamedullarynephron

Renal pelvis

Renalcortex

Renalmedulla

Nephron Organization

Afferent arteriolefrom renal artery Glomerulus

Bowman’scapsule

Proximaltubule

Peritubularcapillaries

Distaltubule

Efferentarteriolefrom glomerulus

Collectingduct

Branch ofrenal vein

Vasarecta

Descendinglimb

Ascendinglimb

Loopof

Henle

200

m

Blood vessels from a humankidney. Arterioles and peritubularcapillaries appear pink; glomeruliappear yellow.

Figure 44.14-b

© 2011 Pearson Education, Inc.

Animation: Bowman’s Capsule and Proximal Tubule Right-click slide / select “Play”

Proximal tubule Distal tubule

Filtrate

CORTEX

Loop ofHenle

OUTERMEDULLA

INNERMEDULLA

Key

Active transport

Passive transport

Collectingduct

NutrientsNaCl

NH3

HCO3 H2O K

H

NaCl

H2O

HCO3

K H

H2O

NaCl

NaCl

NaCl H2O

Urea

Figure 44.15

© 2011 Pearson Education, Inc.

Animation: Loop of Henle and Distal TubuleRight-click slide / select “Play”

© 2011 Pearson Education, Inc.

Animation: Collecting DuctRight-click slide / select “Play”

Osmolarityof interstitial

fluid(mOsm/L)

1,200

900

600

400

300

Key

Activetransport

Passivetransport

INNERMEDULLA

OUTERMEDULLA

CORTEXH2O

H2O

H2O

H2O

H2O

H2O

H2O

1,200

900

600

400

300

300

300

Figure 44.16-1

Osmolarityof interstitial

fluid(mOsm/L)

1,200

900

600

400

300

Key

Activetransport

Passivetransport

INNERMEDULLA

OUTERMEDULLA

CORTEXNaClH2O

H2O

H2O

H2O

H2O

H2O

H2O

NaCl

NaCl

NaCl

NaCl

NaCl

NaCl

1,200

100

100

200

400

700900

600

400

300

300

300

Figure 44.16-2

Osmolarityof interstitial

fluid(mOsm/L)

Key

Activetransport

Passivetransport

INNERMEDULLA

OUTERMEDULLA

CORTEXNaClH2O

H2O

H2O

H2O

H2O

H2O

H2O

NaCl

NaCl

NaCl

NaCl

NaCl

NaCl

NaCl

NaCl

H2O

H2O

H2O

H2O

H2O

H2O

H2O

Urea

Urea

Urea

1,200

1,2001,200

900

600

400

300300

400

600

100

100

200

400

700900

600

400

300

300

300

Figure 44.16-3

Loops of Henle quiz…

• Who would have longer loops of Henle,

a beaver or a desert hare?

Loops of Henle quiz…

• Who would have longer loops of Henle,

a beaver or a desert hare?

• WHY?

Figure 44.18 A vampire bat (Desmodus rotundas), a

mammal with a unique excretory situation.

How do we hold our pee

(Micturition reflex video)

Antidiuretic Hormone

• The osmolarity of the urine is regulated by nervous and hormonal control

• Antidiuretic hormone (ADH) makes the collecting duct epithelium more permeable to water– An increase in osmolarity triggers the release of ADH,

which helps to conserve water

© 2011 Pearson Education, Inc.

© 2011 Pearson Education, Inc.

Animation: Effect of ADHRight-click slide / select “Play”

Figure 44.19-1

ThirstHypothalamus

ADH

Pituitarygland

Osmoreceptors inhypothalamus trigger

release of ADH.

STIMULUS:Increase in blood

osmolarity (forinstance, after

sweating profusely)

Homeostasis:Blood osmolarity

(300 mOsm/L)

Figure 44.19-2

ThirstHypothalamus

ADH

Pituitarygland

Osmoreceptors inhypothalamus trigger

release of ADH.

STIMULUS:Increase in blood

osmolarity (forinstance, after

sweating profusely)

Homeostasis:Blood osmolarity

(300 mOsm/L)

Drinking reducesblood osmolarity

to set point.

H2O reab-sorption helpsprevent further

osmolarityincrease.

Increasedpermeability

Distaltubule

Collecting duct

Collectingduct

ADHreceptor

COLLECTINGDUCT CELL

LUMEN

Second-messengersignaling molecule

Storagevesicle

Aquaporinwater channel

Exocytosis

H2O

H2O

ADH

cAMP

Figure 44.20

How might alcohol affect your water

balance?

© 2011 Pearson Education, Inc.

The Renin-Angiotensin-Aldosterone System

• The renin-angiotensin-aldosterone system

(RAAS) is part of a complex feedback circuit

that functions in homeostasis

• A drop in blood pressure near the glomerulus

causes the juxtaglomerular apparatus (JGA)

to release the enzyme renin

• Renin triggers the formation of the peptide

angiotensin II

© 2011 Pearson Education, Inc.

• Angiotensin II

– Raises blood pressure and decreases blood

flow to the kidneys

– Stimulates the release of the hormone

aldosterone, which increases blood volume

and pressure

© 2011 Pearson Education, Inc.

Figure 44.22-1

JGAreleasesrenin.

Renin

Distaltubule

Juxtaglomerularapparatus (JGA)

STIMULUS:Low blood volumeor blood pressure(for example, dueto dehydration or

blood loss)

Homeostasis:Blood pressure,

volume

AngiotensinogenLiver

JGAreleasesrenin.

Renin

Distaltubule

Juxtaglomerularapparatus (JGA)

Angiotensin I

ACE

Angiotensin II

STIMULUS:Low blood volumeor blood pressure(for example, dueto dehydration or

blood loss)

Homeostasis:Blood pressure,

volume

Figure 44.22-2

AngiotensinogenLiver

JGAreleasesrenin.

Renin

Distaltubule

Juxtaglomerularapparatus (JGA)

Angiotensin I

ACE

Angiotensin II

Adrenal gland

Aldosterone

More Na and H2Oare reabsorbed in

distal tubules,increasing blood volume.

Arteriolesconstrict,increasing

blood pressure.

STIMULUS:Low blood volumeor blood pressure(for example, dueto dehydration or

blood loss)

Homeostasis:Blood pressure,

volume

Figure 44.22-3

Homeostatic Regulation of the Kidney

• ADH and RAAS both increase water

reabsorption, but only RAAS will respond to a

decrease in blood volume

• Another hormone, atrial natriuretic peptide

(ANP), opposes the RAAS

• ANP is released in response to an increase in

blood volume and pressure and inhibits the

release of renin

© 2011 Pearson Education, Inc.

Check out Bioflix,

and Bozeman “Osmoregulation”

Test Your Understanding question 7