GAS EXCHANGECardio Respiratory

System

GAS EXCHANGE

1. supplies oxygen for aerobic cellular respiration (reactant)

2. removes carbon dioxide from aerobic cellular respiration (product)

3. Must carry out ventilation - actively moving air in and out of body surfaces

4. Terrestrial – gases in air Aquatic – gases dissolved in water

Fig. 42-2

Circularcanal

Radial canalMouth

(a) The moon jelly Aurelia, a cnidarian The planarian Dugesia, aflatworm

(b)

MouthPharynx

2 mm5 cm

SOME AQUATIC INVERTEBRATES: Thin-wall - Gases diffuse through the membrane

Fig. 42-21

Parapodium (functions as gill)(a) Marine worm

Gills

(b) Crayfish (c) Sea star

Tube foot

Coelom

Gills

OTHER AQUATIC INVERTIEBRATES USE GILLS

Fig. 42-23

Air sacs

Tracheae

Externalopening

Bodycell

AirsacTracheole

Tracheoles Mitochondria Muscle fiber

2.5 µmBody wall

Trachea

Air

Arachnids (Spiders/Scorpians) - Book Lungs

Fig. 42-22

Anatomy of gills

Gillarch

Waterflow Operculum

Gillarch

Gill filamentorganization

Bloodvessels

Oxygen-poor blood

Oxygen-rich blood

Fluid flowthrough

gill filament

Lamella

Blood flow throughcapillaries in lamella

Water flowbetweenlamellae

Countercurrent exchange

PO2 (mm Hg) in water

PO2 (mm Hg) in blood

Net diffu-sion of O2

from waterto blood

150 120 90 60 30

110 80 20Gill filaments

50140

GILLS

Fig. 42-UN4

GAS EXCHANGE THROUGH SKIN ONLY SKIN LUNGS

SKIN ONLY

SNAKE RESPIRATORY

REPTILES

DINOSAUR BIRD BONES

Fig. 42-26

Anteriorair sacs

Posteriorair sacs Lungs

Air

Lungs

Air

1 mm

Trachea

Air tubes(parabronchi)in lung

EXHALATIONAir sacs empty; lungs fill

INHALATIONAir sacs fill

LUNGS

Fig. 42-25

Lung

Diaphragm

Airinhaled

Rib cageexpands asrib musclescontract

Rib cage getssmaller asrib musclesrelax

Airexhaled

EXHALATIONDiaphragm relaxes

(moves up)

INHALATIONDiaphragm contracts

(moves down)

Air Volume

Fig. 42-27

Breathingcontrolcenters

Cerebrospinalfluid

Pons

Medullaoblongata

Carotidarteries

Aorta

DiaphragmRib muscles

Fig. 42-UN2Inhaled air Exhaled air

Alveolarepithelial cells

Alveolar spaces

CO2 O2

CO 2 O2

Alveolarcapillaries of

lung

Pulmonary veinsPulmonary arteries

Systemic veins Systemic arteries

Heart

SystemiccapillariesCO

2 O 2

CO2 O2

Body tissue

Fig. 42-28Alveolus

PO2 = 100 mm Hg

PO2 = 40 PO2

= 100

PO2 = 100PO2

= 40

Circulatorysystem

Body tissuePO2

≤ 40 mm Hg PCO2 ≥ 46 mm Hg

Body tissue

PCO2 = 46 PCO2

= 40

PCO2 = 40PCO2

= 46

Circulatorysystem

PCO2 = 40 mm Hg

Alveolus

(b) Carbon dioxide(a) Oxygen

Fig. 42-UN1

Chains

IronHeme

ChainsHemoglobin

HEMOGLOBIN

OXYGEN EXCHANGE

Fig. 42-29a

O2 unloadedto tissuesat rest

O2 unloadedto tissues

during exercise

100

40

0

20

60

80

0 40 80 100

O2 s

atur

ation

of h

emog

lobi

n (%

)

20 60

Tissues duringexercise

Tissuesat rest

Lungs

PO2 (mm Hg)

(a) PO2 and hemoglobin dissociation at pH 7.4

Fig. 42-29b

O2 s

atur

ation

of h

emog

lobi

n (%

)

40

0

20

60

80

0 40 80 10020 60

100

PO2 (mm Hg)

(b) pH and hemoglobin dissociation

pH 7.4pH 7.2

Hemoglobinretains lessO2 at lower pH(higher CO2

concentration)

Fig. 42-UN3

Fetus

Mother

100

80

60

40

20

00 20 40 60 80

O2 s

atur

ation

of

hem

oglo

bin

(%)

100

PO2 (mm Hg)

Fig. 42-30aBody tissue

CO2 produced

CO2 transportfrom tissues

Interstitialfluid CO2

CO2

CO2

Plasmawithin capillary

Capillarywall

H2O

H2CO3

Carbonic acid

Redbloodcell

Hemoglobinpicks up

CO2 and H+Hb

H+HCO3–

Bicarbonate+

HCO3–

To lungs

Fig. 42-30b

HCO3–

HCO3– H++

CO2 transportto lungs

Hemoglobinreleases

CO2 and H+HbH2CO3

H2O

CO2

Plasma withinlung capillary

CO2

CO2

CO2

Alveolar space in lung

CARBON DIOXIDE