figure 42.1. how does blood help regulate homeostasis?
TRANSCRIPT
Figure 42.1
How does blood help regulate homeostasis?
How does blood help regulate homeostasis?
• pH• Oxygen
• Nitrogen • Osmolality• Sugar• Minerals (e.g. calcium)
LECTURE PRESENTATIONSFor CAMPBELL BIOLOGY, NINTH EDITION
Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson
© 2011 Pearson Education, Inc.
Lectures byErin Barley
Kathleen Fitzpatrick
Circulation and Gas Exchange
Chapter 42
Figure 42.2
Circularcanal
Mouth
Radial canals 5 cm
(a) The moon jelly Aurelia, a cnidarian (b) The planarian Dugesia, a flatworm
Gastrovascularcavity
Mouth
Pharynx2 mm
Figure 42.3
(a) An open circulatory system
Heart
Hemolymph in sinusessurrounding organs
Pores
Tubular heart
Dorsalvessel
(main heart)
Auxiliaryhearts
Small branchvessels ineach organ
Ventral vessels
Blood
Interstitial fluid
Heart
(b) A closed circulatory system
Figure 42.4
(a) Single circulation (b) Double circulation
Artery
Heart:
Atrium (A)
Ventricle (V)
Vein
Gillcapillaries
Bodycapillaries
Key
Oxygen-rich blood
Oxygen-poor blood
Systemic circuit
Systemiccapillaries
Right Left
A A
VV
Lungcapillaries
Pulmonary circuit
Figure 42.5
Amphibians Reptiles (Except Birds)
Pulmocutaneous circuit Pulmonary circuit
Lungand skincapillaries
Atrium(A)
Atrium(A)
LeftRight
Ventricle (V)
Systemiccapillaries
Systemic circuit Systemic circuit Systemic circuit
Systemiccapillaries
IncompleteseptumIncompleteseptum
Leftsystemicaorta
LeftRight
Rightsystemicaorta
A A
V V
Lungcapillaries
Lungcapillaries
Pulmonary circuit
A AV V
LeftRight
Systemiccapillaries
Key
Oxygen-rich bloodOxygen-poor blood
Mammals and Birds
• In reptiles and mammals, oxygen-poor blood flows through the pulmonary circuit to pick up oxygen through the lungs
• In amphibians, oxygen-poor blood flows through a pulmocutaneous circuit to pick up oxygen– WHAT IS THE DIFFERENCE? – WHY DO AMPHIBIANS BOTHER?– Do they need lungs when underwater?
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PATHWAY OF BLOOD, POST-HEART
Aorta
Arterie
sArte
riole
s
Capill
arie
sVen
ules
Veins
Venae
cava
e
Systolicpressure
Diastolicpressure
020406080
100120
01020304050
Pre
ss
ure
(mm
Hg
)V
elo
cit
y(c
m/s
ec
)A
rea
(c
m2)
01,0002,0003,0004,0005,000
• Heart animation
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Animation: Path of Blood Flow in Mammals
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Animation: Path of Blood Flow in MammalsRight-click slide / select “Play”
Superior vena cava
Pulmonaryartery
Capillariesof right lung
Pulmonaryvein
Aorta
Inferiorvena cava
Right ventricle
Capillaries ofabdominal organsand hind limbs
Right atrium
Aorta
Left ventricle
Left atrium
Pulmonary vein
Pulmonaryartery
Capillariesof left lung
Capillaries ofhead and forelimbs
Figure 42.6
Figure 42.7
Pulmonary artery
Rightatrium
Semilunarvalve
Atrioventricularvalve
Rightventricle
Leftventricle
Atrioventricularvalve
Semilunarvalve
Leftatrium
Pulmonaryartery
Aorta
• The heart contracts and relaxes in a rhythmic cycle called the cardiac cycle
• The contraction, or pumping, phase is called systole
• The relaxation, or filling, phase is called diastole
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Figure 42.8-1
Atrial andventricular diastole
0.4sec
1
Figure 42.8-2
Atrial andventricular diastole
Atrial systole and ventricular diastole
0.1sec
0.4sec
2
1
Figure 42.8-3
Atrial andventricular diastole
Atrial systole and ventricular diastole
Ventricular systole and atrialdiastole
0.1sec
0.4sec
0.3 sec
2
1
3
• The heart rate, also called the pulse, is the number of beats per minute
• The stroke volume is the amount of blood pumped in a single contraction
• The cardiac output is the volume of blood pumped into the systemic circulation per minute and depends on both the heart rate and stroke volume
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• The “lub-dup” sound of a heart beat is caused by the recoil of blood against the AV valves (lub) then against the semilunar (dup) valves
• Backflow of blood through a defective valve causes a heart murmur
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Maintaining the Heart’s Rhythmic Beat
• Some cardiac muscle cells are self-excitable, meaning they contract without any signal from the nervous system
• The sinoatrial (SA) node, or pacemaker, sets the rate and timing at which cardiac muscle cells contract
• Impulses that travel during the cardiac cycle can be recorded as an electrocardiogram (ECG or EKG)
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Figure 42.9-1
SA node(pacemaker)
ECG
1
Figure 42.9-2
SA node(pacemaker)
AVnode
ECG
1 2
Figure 42.9-3
SA node(pacemaker)
AVnode Bundle
branches Heartapex
ECG
1 2 3
Figure 42.9-4
SA node(pacemaker)
AVnode Bundle
branches Heartapex
Purkinjefibers
ECG
1 2 3 4
• The pacemaker is regulated by two portions of the nervous system: the sympathetic and parasympathetic divisions– The sympathetic division speeds up the pacemaker– The parasympathetic division slows down the
pacemaker• The pacemaker is also regulated by hormones and temperature
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Blood fun facts• It takes a drop of blood 20 to 60 seconds for one round-
trip from and to the heart.• We have approximately 100,000 miles of blood vessels • Two million red blood cells die every second.• The kidneys filter over 400 gallons of blood each day.• The average life span of a single red blood cell is 120
days.• There are 150 billion red blood cells in one ounce of
blood• Our hearts pump 48 million gallons of blood/year (in 10
oz. intervals)• White blood cells only last 4-6 hours
Concept 42.3: Patterns of blood pressure and flow reflect the structure and arrangement of blood vessels
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Blood Vessel Structure and Function
• A vessel’s cavity is called the central lumen• The epithelial layer that lines blood vessels is
called the endothelium• The endothelium is smooth and minimizes
resistance– Why might high blood pressure lead to problems?
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The structure of blood vessels
Artery
Red blood cells
Endothelium
Artery
Smoothmuscle
Connectivetissue
Capillary
Valve
Vein
Vein
Basal lamina
Endothelium
Smoothmuscle
Connectivetissue
100 m
LM
Venule
15
mL
M
Arteriole
Red blood cell
Capillary
• Nitric oxide is a major inducer of vasodilation• The peptide endothelin is an important inducer of
vasoconstriction
Under what circumstances does the body use them?
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Blood Pressure and Gravity
• Blood pressure is generally measured for an artery in the arm at the same height as the heart
• Blood pressure for a healthy 20-year-old at rest is 120 mm Hg at systole and 70 mm Hg at diastole
• Fainting is caused by inadequate blood flow to the head– Which animals are at greatest risk?
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Blood pressure reading: 120/70
120
70
Soundsstop
Soundsaudible instethoscope
120
Arteryclosed
1 2 3
Figure 42.12
Direction of blood flowin vein (toward heart) Valve (open)
Skeletal muscle
Valve (closed)
Blood is moved through veins by smooth muscle contraction, skeletal muscle contraction, and expansion of the vena cava with inhalationOne-way valves in veins prevent backflow of blood
Capillary Function
• Blood flows through only 510% of the body’s capillaries at a time
Two mechanisms regulate distribution of blood in capillary beds1. Contraction of the smooth muscle layer in the wall of an
arteriole constricts the vessel
2. Precapillary sphincters control flow of blood between arterioles and venules
• Blood flow is regulated by nerve impulses, hormones, and other chemicals
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Figure 42.14Precapillarysphincters
Thoroughfarechannel
Arteriole
CapillariesVenule
(a) Sphincters relaxed
Arteriole Venule
(b) Sphincters contracted
Fluid exchange between capillaries and the interstitial fluid.
INTERSTITIALFLUID Net fluid movement out
Bloodpressure
Osmoticpressure
Arterial endof capillary Direction of blood flow
Venous endof capillary
Body cell
Fluid Return by the Lymphatic System
• The lymphatic system returns fluid that leaks out from the capillary beds
• Fluid, called lymph, reenters the circulation directly at the venous end of the capillary bed and indirectly through the lymphatic system– The lymphatic system drains into veins in the neck– Valves in lymph vessels prevent the backflow of fluid
• Lymph nodes are organs that filter lymph and play an important role in the body’s defense
– Edema is swelling caused by disruptions in the flow of lymph
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LYMPH NODES AND VESSELS. Where are these?
Concept 42.4: Blood components contribute to exchange, transport, and defense
• With open circulation, the fluid that is pumped comes into direct contact with all cells
• The closed circulatory systems of vertebrates contain blood, a specialized connective tissue
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The composition of mammalian blood
Plasma 55%
Constituent Major functions
Water
Ions (bloodelectrolytes)SodiumPotassiumCalciumMagnesiumChlorideBicarbonate
Solvent forcarrying othersubstances
Osmotic balance,pH buffering,and regulationof membranepermeability
Plasma proteinsOsmotic balance,pH buffering
Albumin
Fibrinogen
Immunoglobulins(antibodies)
Clotting
Defense
Substances transported by blood
NutrientsWaste productsRespiratory gasesHormones
Separatedbloodelements
Basophils
Neutrophils Monocytes
Lymphocytes
Eosinophils
Platelets
Erythrocytes (red blood cells) 5–6 million
250,000–400,000 Bloodclotting
Transportof O2 and
some CO2
Defense andimmunity
FunctionsNumber per L(mm3) of blood
Cell type
Cellular elements 45%
Leukocytes (white blood cells) 5,000–10,000
Cellular Elements
• Suspended in blood plasma are three large components
1. Red blood cells (erythrocytes) transport oxygen O2
2. White blood cells (leukocytes) function in defense
3. Platelets, a third cellular element, are fragments of cells that are involved in clotting
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• Red blood cells, or erythrocytes, are by far the most numerous blood cells– They contain hemoglobin, the iron-containing protein
that transports O2
– Each molecule of hemoglobin binds up to four molecules of O2
– In mammals, mature erythrocytes lack nuclei and mitochondria
Erythrocytes
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Leukocytes• There are five major types of white blood cells, or
leukocytes: monocytes, neutrophils, basophils, eosinophils, and lymphocytes– They function in defense by phagocytizing bacteria and
debris or by producing antibodies– They are found both in and outside of the circulatory
system
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Blood clotting and formation of a thrombus
Collagen fibers
1 2 3
PlateletPlateletplug
Fibrinclot
Fibrin clot formation
Red blood cell 5 m
Clotting factors from:PlateletsDamaged cellsPlasma (factors include calcium, vitamin K)
Enzymatic cascade
Prothrombin Thrombin
Fibrinogen Fibrin
Stem cells(in bone marrow)
Myeloidstem cells
Lymphoidstem cells
B cells T cells
Lymphocytes
ErythrocytesNeutrophils
Basophils
EosinophilsPlateletsMonocytes
Figure 42.19Stem Cells and the Replacement of Cellular Elements
Cardiovascular Disease
• Cardiovascular diseases account for more than half the deaths in the United States
• Cholesterol, a steroid, helps maintain membrane fluidity
• Low-density lipoprotein (LDL) delivers cholesterol to cells for membrane production
• High-density lipoprotein (HDL) scavenges cholesterol for return to the liver– Risk for heart disease increases with a high LDL to HDL
ratio
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Lumen of artery
Smoothmuscle
EndotheliumPlaque
Smoothmusclecell
T lymphocyte
Extra-cellularmatrix
Foam cellMacrophage
Plaque rupture
LDL
CholesterolFibrous cap
1 2
43
One type of cardiovascular disease,
athero-sclerosis, is caused by the buildup of plaque deposits within arteries
causes strokes and heart attacks
• A heart attack, or myocardial infarction, is the death of cardiac muscle tissue resulting from blockage of one or more coronary arteries
• Coronary arteries supply oxygen-rich blood to the heart muscle
• A stroke is the death of nervous tissue in the brain, usually resulting from rupture or blockage of arteries in the head
• Angina pectoris is caused by partial blockage of the coronary arteries and results in chest pains
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Heart health issues
Figure 42.21
Individuals with two functional copies ofPCSK9 gene (control group)
Plasma LDL cholesterol (mg/dL)
Individuals with an inactivating mutation inone copy of PCSK9 gene
Plasma LDL cholesterol (mg/dL)
Average 63 mg/dLAverage 105 mg/dL30
20
10
00 50 100 150 200 250 300 0
0
10
20
30
50 100 150 200 250 300
Per
cen
t o
f in
div
idu
als
RESULTS
Per
cen
t o
f in
div
idu
als
Concept 42.5: Gas exchange occurs across specialized respiratory surfaces
• Gas exchange supplies O2 for cellular respiration and disposes of CO2
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Partial Pressure Gradients in Gas Exchange
• A gas diffuses from a region of higher partial pressure to a region of lower partial pressure– Partial pressure is the pressure exerted by a particular
gas in a mixture of gases
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Figure 42.22
Parapodium(functions as gill)
(a) Marine worm (b) Crayfish
GillsGills
Tube foot
(c) Sea star
Coelom
Figure 42.23
Gillarch
O2-poor blood
O2-rich blood
Bloodvessels
Gill arch
OperculumWaterflow
Water flowBlood flow
Countercurrent exchange
PO (mm Hg) in water2
150
PO (mm Hg)
in blood2
120 90 60 30
140 110 80 50 20Net diffu-sion of O2
Lamella
Gill filaments
Tracheoles Mitochondria Muscle fiber
2.5
m
Tracheae
Air sacs
External opening
Trachea
Airsac Tracheole
Bodycell
Air
Figure 42.24
Human respiration bioflix
Pharynx
Larynx(Esophagus)
Trachea
Right lung
Bronchus
Bronchiole
Diaphragm(Heart)
Capillaries
Leftlung
Dense capillary bedenveloping alveoli (SEM)
50 m
Alveoli
Branch ofpulmonary artery(oxygen-poorblood)
Branch ofpulmonary vein(oxygen-richblood)
Terminalbronchiole
Nasalcavity
RDS deaths Deaths from other causesRESULTS
40
30
20
10
00 800 1,600 2,400 3,200 4,000
Body mass of infant (g)
Su
rfac
e te
nsi
on
(d
ynes
/cm
)
What causes respiratory distress syndrome?
How an Amphibian Breathes
• An amphibian such as a frog ventilates its lungs by positive pressure breathing, which forces air down the trachea
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How a Bird Breathes
• Birds have eight or nine air sacs that function as bellows that keep air flowing through the lungs
• Air passes through the lungs in one direction only
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Anteriorair sacs
Posteriorair sacs
Lungs
1 mm
Airflow
Air tubes(parabronchi)in lung
Anteriorair sacs
Lungs
Second inhalationFirst inhalation
Posteriorair sacs 3
2 4
1
4
31
2 Second exhalationFirst exhalation
Figure 42.27
How a Mammal Breathes
• Mammals ventilate their lungs by negative pressure breathing, which pulls air into the lungs
• Lung volume increases as the rib muscles and diaphragm contract
• The tidal volume is the volume of air inhaled with each breath
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Figure 42.28
Rib cageexpands.
Airinhaled.
Airexhaled.
Rib cage getssmaller.
1 2
Lung
Diaphragm
Control of Breathing in Humans
• In humans, the main breathing control centers are in two regions of the brain, the medulla oblongata and the pons
– The medulla regulates the rate and depth of breathing in response to pH changes in the cerebrospinal fluid
– The medulla adjusts breathing rate and depth to match metabolic demands
– The pons regulates the tempo
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• Sensors in the aorta and carotid arteries monitor O2 and CO2 concentrations in the blood– These sensors exert secondary control over breathing
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Homeostasis:Blood pH of about 7.4
CO2 level
decreases. Stimulus:Rising level ofCO2 in tissues
lowers blood pH.Response:Rib musclesand diaphragmincrease rateand depth ofventilation.
Carotidarteries
AortaSensor/control center:Cerebrospinal fluid
Medullaoblongata
Figure 42.29
Concept 42.7: Adaptations for gas exchange include pigments that bind and transport gases
• The metabolic demands of many organisms require that the blood transport large quantities of O2 and CO2
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Exhaled air Inhaled air
Pulmonaryarteries
Systemicveins
Systemicarteries
Pulmonaryveins
Alveolarcapillaries
AlveolarspacesAlveolar
epithelialcells
Inhaledair
160
120
80
40
0Heart
8 1
2
3
46
7
CO2 O2
SystemiccapillariesCO2 O2
Body tissue5
(a) The path of respiratory gases in the circulatory system
(b) Partial pressure of O2 and CO2 at different points in the
circulatory system numbered in (a)
4321 5 6 7
Exhaledair
Pa
rtia
l p
res
su
re (
mm
Hg
)
PO2
PCO 2
8
Figure 42.30
Coordination of Circulation and Gas Exchange
• Blood arriving in the lungs has a low partial pressure of O2 and a high partial pressure of CO2 relative to air in the alveoli
• In the alveoli, O2 diffuses into the blood and CO2 diffuses into the air
• In tissue capillaries, partial pressure gradients favor diffusion of O2 into the interstitial fluids and CO2 into the blood
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Respiratory Pigments
• Respiratory pigments, proteins that transport oxygen, greatly increase the amount of oxygen that blood can carry– Arthropods and many molluscs have hemocyanin with
copper as the oxygen-binding component– Most vertebrates and some invertebrates use
hemoglobin – In vertebrates, hemoglobin is contained within
erythrocytes
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Hemoglobin
• A single hemoglobin molecule can carry four molecules of O2, one molecule for each iron- containing heme group– CO2 produced during cellular respiration lowers blood
pH and decreases the affinity of hemoglobin for O2; this is called the Bohr shift
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Figure 42.UN01
Iron
Heme
Hemoglobin
Figure 42.31
2(a) PO and hemoglobin dissociation at pH 7.4
Tissues duringexercise
Tissuesat rest
Lungs
PO (mm Hg)2
(b) pH and hemoglobin dissociation
PO (mm Hg)2
0 20 40 60 80 1000
20
40
60
80
100
0 20 40 60 80 1000
20
40
60
80
100
Hemoglobinretains lessO2 at lower pH
(higher CO2
concentration)
pH 7.2pH 7.4
O2 unloaded
to tissuesduring exercise
O2 s
atu
rati
on
of
he
mo
glo
bin
(%
)
O2 unloaded
to tissuesat rest
O2 s
atu
rati
on
of
he
mo
glo
bin
(%
)
Carbon Dioxide Transport
• Hemoglobin also helps transport CO2 and assists in buffering the blood
• CO2 from respiring cells diffuses into the blood and is transported in blood plasma, bound to hemoglobin, or as bicarbonate ions (HCO3
–)
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Animation: O2 from Lungs to Blood
Animation: CO2 from Blood to Lungs
Animation: CO2 from Tissues to Blood
Animation: O2 from Blood to Tissues
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Animation: O2 from Blood to Tissues Right-click slide / select “Play”
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Animation: CO2 from Tissues to Blood Right-click slide / select “Play”
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Animation: CO2 from Blood to Lungs Right-click slide / select “Play”
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Animation: O2 from Lungs to Blood Right-click slide / select “Play”
Figure 42.32 Body tissue
Capillarywall
Interstitialfluid
Plasmawithin capillary
CO2 transport
from tissuesCO2 produced
CO2
CO2
CO2
H2O
H2CO3 HbRedbloodcell Carbonic
acid
Hemoglobin (Hb)picks up
CO2 and H+.
H+HCO3
Bicarbonate
HCO3
HCO3
To lungs
CO2 transport
to lungs
HCO3
H2CO3
H2O
CO2
H+
HbHemoglobin
releases
CO2 and H+.
CO2
CO2
CO2
Alveolar space in lung
Respiratory Adaptations of Diving Mammals
• Diving mammals have evolutionary adaptations that allow them to perform extraordinary feats
– For example, Weddell seals in Antarctica can remain underwater for 20 minutes to an hour
– For example, elephant seals can dive to 1,500 m and remain underwater for 2 hours
• These animals have a high blood to body volume ratio
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• Deep-diving air breathers stockpile O2 and deplete it slowly
• Diving mammals can store oxygen in their muscles in myoglobin proteins
• Diving mammals also conserve oxygen by– Changing their buoyancy to glide passively
– Decreasing blood supply to muscles
– Deriving ATP in muscles from fermentation once oxygen is depleted
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Figure 42.UN02
Exhaled air
Alveolarepithelialcells
Pulmonaryarteries
Systemicveins
Heart
CO2 O2
Body tissue
Systemiccapillaries
Systemicarteries
Pulmonaryveins
Alveolarcapillaries
Alveolarspaces
Inhaled air
CO2 O2
Figure 42.UN03
Fetus
Mother
PO (mm Hg)2
0 20 40 60 80 100
100
80
60
40
20
0
O2
satu
rati
on
of
hem
og
lob
in (
%)
Figure 42.UN04