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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 PRESENTATIONS
For CAMPBELL BIOLOGY, NINTH EDITION
Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson
Chapter 42
Circulation and Gas Exchange
Lectures by
Erin Barley
Kathleen Fitzpatrick
© 2011 Pearson Education, Inc.
Figure 42.2
Circular
canal
Mouth
Gastrovascular
cavity
Mouth
Pharynx
Radial canals
5 cm
(a) The moon jelly Aurelia, a cnidarian
2 mm
(b) The planarian Dugesia, a flatworm
Figure 42.3
(a) An open circulatory system
(b) A closed circulatory system
Heart
Heart
Interstitial fluid
Hemolymph in sinuses
surrounding organs
Pores
Blood
Small branch
vessels in
each organ
Dorsal
Auxiliary
vessel
hearts
(main heart)
Tubular heart
Ventral vessels
Figure 42.4
(a) Single circulation
(b) Double circulation
Pulmonary circuit
Gill
capillaries
Lung
capillaries
Artery
Heart:
A
Atrium (A)
V
Right
Ventricle (V)
A
V
Left
Vein
Systemic
capillaries
Body
capillaries
Systemic circuit
Key
Oxygen-rich blood
Oxygen-poor blood
Figure 42.5
Amphibians
Pulmocutaneous circuit
Pulmonary circuit
Lung
and skin
capillaries
Atrium
(A)
Atrium
(A)
Right
Pulmonary circuit
Lung
capillaries
Lung
capillaries
Right
systemic
aorta
A
V
Right
Left
Mammals and Birds
Reptiles (Except Birds)
A
V
Left
Left
systemic
aorta
Incomplete
septum
A
V
Right
A
V
Left
Ventricle (V)
Systemic circuit
Key
Oxygen-rich blood
Oxygen-poor blood
Systemic
capillaries
Systemic
capillaries
Systemic
capillaries
Systemic circuit
Systemic circuit
• 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?
© 2011 Pearson Education, Inc.
Velocity
(cm/sec)
5,000
4,000
3,000
2,000
1,000
0
50
40
30
20
10
0
Pressure
(mm Hg)
Area (cm2)
PATHWAY OF
BLOOD,
POST-HEART
120
100
80
60
40
20
0
Systolic
pressure
Diastolic
pressure
• Heart animation
Animation: Path of Blood Flow in Mammals
© 2011 Pearson Education, Inc.
Animation: Path of Blood Flow in Mammals
Right-click slide / select “Play”
© 2011 Pearson Education, Inc.
Figure 42.6
Capillaries of
head and forelimbs
Superior vena cava
Pulmonary
artery
Capillaries
of right lung
Pulmonary
vein
Right atrium
Right ventricle
Pulmonary
artery
Aorta
Capillaries
of left lung
Pulmonary vein
Left atrium
Left ventricle
Aorta
Inferior
vena cava
Capillaries of
abdominal organs
and hind limbs
Figure 42.7
Aorta
Pulmonary artery
Pulmonary
artery
Right
atrium
Left
atrium
Semilunar
valve
Semilunar
valve
Atrioventricular
valve
Atrioventricular
valve
Right
ventricle
Left
ventricle
• 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
© 2011 Pearson Education, Inc.
Figure 42.8-1
1 Atrial and
ventricular diastole
0.4
sec
Figure 42.8-2
2 Atrial systole and ventricular
diastole
1 Atrial and
ventricular diastole
0.1
sec
0.4
sec
Figure 42.8-3
2 Atrial systole and ventricular
diastole
1 Atrial and
ventricular diastole
0.1
sec
0.4
sec
0.3 sec
3 Ventricular systole and atrial
diastole
• 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
© 2011 Pearson Education, Inc.
• 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
© 2011 Pearson Education, Inc.
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)
© 2011 Pearson Education, Inc.
Figure 42.9-1
1
SA node
(pacemaker)
ECG
Figure 42.9-2
1
SA node
(pacemaker)
ECG
2
AV
node
Figure 42.9-3
1
SA node
(pacemaker)
ECG
2
AV
node
3
Bundle
branches
Heart
apex
Figure 42.9-4
1
SA node
(pacemaker)
ECG
2
AV
node
3
Bundle
branches
4
Heart
apex
Purkinje
fibers
• 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
© 2011 Pearson Education, Inc.
Blood fun facts
• It takes a drop of blood 20 to 60 seconds for one roundtrip 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
© 2011 Pearson Education, Inc.
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?
© 2011 Pearson Education, Inc.
Artery
LM
The
structure
of blood
vessels
Vein
Red blood cells
100 m
Valve
Basal lamina
Endothelium
Endothelium
Smooth
muscle
Connective
tissue
Capillary
Smooth
muscle
Connective
tissue
Artery
Vein
Capillary
15 m
Red blood cell
Venule
LM
Arteriole
• 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?
© 2011 Pearson Education, Inc.
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?
© 2011 Pearson Education, Inc.
Figure 42.12
Blood pressure reading: 120/70
1
3
2
120
120
70
Artery
closed
Sounds
audible in
stethoscope
Sounds
stop
Blood is moved through veins by smooth muscle contraction, skeletal
muscle contraction, and expansion of the vena cava with inhalation
One-way valves in veins prevent backflow of blood
Direction of blood flow
in vein (toward heart)
Valve (open)
Skeletal muscle
Valve (closed)
Capillary Function
• Blood flows through only 510% of the body’s
capillaries at a time
Two mechanisms regulate distribution of blood in
capillary beds
1. 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
© 2011 Pearson Education, Inc.
Figure 42.14
Precapillary
sphincters
Thoroughfare
channel
Arteriole
(a) Sphincters relaxed
Arteriole
(b) Sphincters contracted
Capillaries
Venule
Venule
Fluid exchange between capillaries and the
interstitial fluid.
INTERSTITIAL
FLUID
Net fluid movement out
Body cell
Blood
pressure
Osmotic
pressure
Arterial end
of capillary
Direction of blood flow
Venous end
of capillary
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
© 2011 Pearson Education, Inc.
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
© 2011 Pearson Education, Inc.
The composition of mammalian blood
Cellular elements 45%
Plasma 55%
Constituent
Water
Solvent for
carrying other
substances
Ions (blood
electrolytes)
Sodium
Potassium
Calcium
Magnesium
Chloride
Bicarbonate
Osmotic balance,
pH buffering,
and regulation
of membrane
permeability
Plasma proteins
Albumin
Fibrinogen
Leukocytes (white blood cells)
Separated
blood
elements
5,000–10,000
Functions
Defense and
immunity
Lymphocytes
Basophils
Eosinophils
Neutrophils
Osmotic balance,
pH buffering
Monocytes
Platelets
250,000–400,000
Clotting
Immunoglobulins Defense
(antibodies)
Substances transported by blood
Nutrients
Waste products
Respiratory gases
Hormones
Number per L
(mm3) of blood
Cell type
Major functions
Erythrocytes (red blood cells)
5–6 million
Blood
clotting
Transport
of O2 and
some CO2
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
© 2011 Pearson Education, Inc.
Erythrocytes
• 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
© 2011 Pearson Education, Inc.
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
© 2011 Pearson Education, Inc.
Blood clotting and formation of a thrombus
2
1
3
Collagen fibers
Platelet
plug
Platelet
Fibrin
clot
Clotting factors from:
Platelets
Damaged cells
Plasma (factors include calcium, vitamin K)
Enzymatic cascade
Prothrombin

Thrombin
Fibrinogen
Fibrin
Red blood cell
Fibrin clot formation
5 m
Stem Cells and
the Replacement
of Cellular
Elements
Figure 42.19
Stem cells
(in bone marrow)
Myeloid
stem cells
Lymphoid
stem cells
B cells T cells
Erythrocytes
Neutrophils
Basophils
Lymphocytes
Monocytes
Platelets
Eosinophils
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
© 2011 Pearson Education, Inc.
Lumen of artery
Endothelium
Smooth
muscle
1
Plaque
2
One type of
cardiovascular
disease,
atherosclerosis, is
caused by the
buildup of plaque
deposits within
arteries
LDL
causes strokes and
heart attacks
Foam cell
Macrophage
Extracellular
matrix
Plaque rupture
4
3
Fibrous cap
Cholesterol
Smooth
muscle
cell
T lymphocyte
Heart health issues
• 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
© 2011 Pearson Education, Inc.
Figure 42.21
Average  105 mg/dL
30
20
10
0
0
50
100
150
200
250
300
Plasma LDL cholesterol (mg/dL)
Individuals with two functional copies of
PCSK9 gene (control group)
Percent of individuals
Percent of individuals
RESULTS
Average  63 mg/dL
30
20
10
0
0
50
100
150
200
250
300
Plasma LDL cholesterol (mg/dL)
Individuals with an inactivating mutation in
one copy of PCSK9 gene
Concept 42.5: Gas exchange occurs across
specialized respiratory surfaces
• Gas exchange supplies O2 for cellular respiration
and disposes of CO2
© 2011 Pearson Education, Inc.
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
© 2011 Pearson Education, Inc.
Figure 42.22
Coelom
Gills
Parapodium
(functions as gill)
(a) Marine worm
Gills
Tube foot
(b) Crayfish
(c) Sea star
Figure 42.23
O2-poor blood
Gill
arch
O2-rich blood
Lamella
Blood
vessels
Gill arch
Water
flow
Operculum
Water flow
Blood flow
Countercurrent exchange
PO (mm Hg) in water
2
150 120 90 60 30
Gill filaments
Net diffusion of O2
140 110 80 50 20
PO (mm Hg)
2
in blood
Tracheoles Mitochondria
Muscle fiber
2.5 m
Figure 42.24
Tracheae
Air sacs
Body
cell
Air
sac
Tracheole
Trachea
External opening
Air
Human respiration bioflix
Branch of
pulmonary vein
(oxygen-rich
blood)
Terminal
bronchiole
Branch of
pulmonary artery
(oxygen-poor
blood)
Nasal
cavity
Pharynx
Left
lung
Larynx
(Esophagus)
Alveoli
50 m
Trachea
Right lung
Capillaries
Bronchus
Bronchiole
Diaphragm
(Heart)
Dense capillary bed
enveloping alveoli (SEM)
What causes respiratory distress syndrome?
RDS deaths
Surface tension (dynes/cm)
RESULTS
Deaths from other causes
40
30
20
10
0
0
800
1,600
2,400
3,200
Body mass of infant (g)
4,000
How an Amphibian Breathes
• An amphibian such as a frog ventilates its lungs by
positive pressure breathing, which forces air
down the trachea
© 2011 Pearson Education, Inc.
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
© 2011 Pearson Education, Inc.
Figure 42.27
Anterior
air sacs
Posterior
air sacs
Lungs
Airflow
Air tubes
(parabronchi)
in lung
1 mm
Posterior
air sacs
Lungs
3
Anterior
air sacs
2
4
1
1 First inhalation
3 Second inhalation
2 First exhalation
4 Second exhalation
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
© 2011 Pearson Education, Inc.
Figure 42.28
1
Rib cage
expands.
2
Air
inhaled.
Lung
Diaphragm
Rib cage gets
smaller.
Air
exhaled.
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
© 2011 Pearson Education, Inc.
• Sensors in the aorta and carotid arteries monitor
O2 and CO2 concentrations in the blood
– These sensors exert secondary control over breathing
© 2011 Pearson Education, Inc.
Figure 42.29
Homeostasis:
Blood pH of about 7.4
CO2 level
decreases.
Response:
Rib muscles
and diaphragm
increase rate
and depth of
ventilation.
Stimulus:
Rising level of
CO2 in tissues
lowers blood pH.
Carotid
arteries
Sensor/control center:
Cerebrospinal fluid
Medulla
oblongata
Aorta
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
© 2011 Pearson Education, Inc.
Figure 42.30
Alveolar
epithelial
cells
2 Alveolar
spaces
CO2
O2
Alveolar
capillaries
7 Pulmonary
arteries
3 Pulmonary
veins
6 Systemic
veins
4 Systemic
arteries
Heart
CO2
Partial pressure (mm Hg)
1 Inhaled air
8 Exhaled air
160
O2
5 Body tissue
(a) The path of respiratory gases in the circulatory
system
2
Exhaled
air
120
80
40
0
1
Systemic
capillaries
PO
2
PCO
Inhaled
air
2
3
4
5
6
7
(b) Partial pressure of O2 and CO2 at different points in the
circulatory system numbered in (a)
8
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
© 2011 Pearson Education, Inc.
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
© 2011 Pearson Education, Inc.
Hemoglobin
• A single hemoglobin molecule can carry four
molecules of O2, one molecule for each ironcontaining heme group
– CO2 produced during cellular respiration lowers blood
pH and decreases the affinity of hemoglobin for O2; this
is called the Bohr shift
© 2011 Pearson Education, Inc.
Figure 42.UN01
Iron
Heme
Hemoglobin
100
O2 unloaded
to tissues
at rest
80
O2 unloaded
to tissues
during exercise
60
40
20
0
O2 saturation of hemoglobin (%)
O2 saturation of hemoglobin (%)
Figure 42.31
100
pH 7.4
80
pH 7.2
Hemoglobin
retains less
O2 at lower pH
(higher CO2
concentration)
60
40
20
0
0
20
40
60
Tissues during Tissues
at rest
exercise
PO2 (mm Hg)
80
100
Lungs
(a) PO2 and hemoglobin dissociation at pH 7.4
0
20
40
60
80
PO2 (mm Hg)
(b) pH and hemoglobin dissociation
100
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–)
Animation: O2 from Blood to Tissues
Animation: CO2 from Tissues to Blood
Animation: CO2 from Blood to Lungs
Animation: O2 from Lungs to Blood
© 2011 Pearson Education, Inc.
Animation: O2 from Blood to Tissues
Right-click slide / select “Play”
© 2011 Pearson Education, Inc.
Animation: CO2 from Tissues to Blood
Right-click slide / select “Play”
© 2011 Pearson Education, Inc.
Animation: CO2 from Blood to Lungs
Right-click slide / select “Play”
© 2011 Pearson Education, Inc.
Animation: O2 from Lungs to Blood
Right-click slide / select “Play”
© 2011 Pearson Education, Inc.
Figure 42.32
Body tissue
CO2 produced
CO2 transport
from tissues
Interstitial
CO2
fluid
Plasma
within capillary CO2
H2O
Red
blood
cell
Capillary
wall
CO2
H2CO3
Hb
Carbonic
acid
HCO3 
Bicarbonate
HCO3
H+
To lungs
CO2 transport
to lungs
HCO3
HCO3 
H2CO3
Hemoglobin (Hb)
picks up
CO2 and H+.
H+
Hb
Hemoglobin
releases
CO2 and H+.
H2O
CO2
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
© 2011 Pearson Education, Inc.
• 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
© 2011 Pearson Education, Inc.
Figure 42.UN02
Inhaled air
Exhaled air
Alveolar
epithelial
cells
Alveolar
spaces
CO2
O2
Alveolar
capillaries
Pulmonary
arteries
Pulmonary
veins
Systemic
veins
Systemic
arteries
Heart
CO2
O2
Systemic
capillaries
Body tissue
O2 saturation of
hemoglobin (%)
Figure 42.UN03
100
80
60
Fetus
Mother
40
20
0
0 20 40 60 80 100
PO2 (mm Hg)
Figure 42.UN04
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