Download PowerPoint - Scranton Prep Biology

CAMPBELL BIOLOGY IN FOCUS
Urry • Cain • Wasserman • Minorsky • Jackson • Reece
34
Circulation and
Gas Exchange
Lecture Presentations by
Kathleen Fitzpatrick and Nicole Tunbridge
© 2014 Pearson Education, Inc.
Overview: Trading Places
 The resources that animal cells require, such as
nutrients and O2, enter the cytoplasm by crossing
the plasma membrane
 In unicellular organisms, these exchanges occur
directly with the environment
 Most multicellular organisms rely on specialized
systems that carry out exchange with the environment
and transport materials through the body
© 2014 Pearson Education, Inc.
 Gills are an example of a specialized exchange
system in animals
 O2 diffuses from the water into blood vessels
 CO2 diffuses from blood into the water
 Internal transport and gas exchange are functionally
related in most animals
© 2014 Pearson Education, Inc.
Figure 34.1
© 2014 Pearson Education, Inc.
Concept 34.1: Circulatory systems link exchange
surfaces with cells throughout the body
 Small, nonpolar molecules such as O2 and CO2
move between cells and their immediate
surroundings by diffusion
 Diffusion time is proportional to the square of the
distance travelled
 Diffusion is only efficient over small distances
© 2014 Pearson Education, Inc.
 In small or thin animals, cells can exchange
materials directly with the surrounding medium
 In most animals, cells exchange materials with the
environment via a fluid-filled circulatory system
© 2014 Pearson Education, Inc.
Gastrovascular Cavities
 Some animals lack a circulatory system
 Some cnidarians, such as jellies, have elaborate
gastrovascular cavities
 A gastrovascular cavity functions in both digestion
and distribution of substances throughout the body
 The body wall that encloses the gastrovascular
cavity is only two cells thick
 Flatworms have a gastrovascular cavity and a flat
body shape to optimize diffusional exchange with
the environment
© 2014 Pearson Education, Inc.
Figure 34.2
Mouth
Gastrovascular
cavity
1 mm
© 2014 Pearson Education, Inc.
Open and Closed Circulatory Systems
 A circulatory system has a circulatory fluid, a set
of interconnecting vessels, and a muscular pump,
the heart
 Several basic types of circulatory systems have
arisen during evolution, each representing
adaptations to constraints of anatomy and
environment
© 2014 Pearson Education, Inc.
 All circulatory systems are either open or closed
 In insects, other arthropods, and some molluscs,
circulatory fluid bathes the organs directly in an
open circulatory system
 In an open circulatory system, there is no distinction
between circulatory fluid and interstitial fluid, and
this general body fluid is called hemolymph
© 2014 Pearson Education, Inc.
Figure 34.3
(a) An open circulatory system
(b) A closed circulatory system
Blood
Heart
Heart
Interstitial
fluid
Hemolymph in sinuses
Branch vessels
in each organ
Pores
Dorsal vessel
(main heart)
Tubular heart
© 2014 Pearson Education, Inc.
Auxiliary
hearts
Ventral vessels
Figure 34.3a
(a) An open circulatory system
Heart
Hemolymph in sinuses
Pores
Tubular heart
© 2014 Pearson Education, Inc.
 In closed circulatory systems the circulatory fluid
called blood is confined to vessels and is distinct
from interstitial fluid
 These systems are found in annelids, most
cephalopods, and all vertebrates
 One or more hearts pump blood through the vessels
 Chemical exchange occurs between blood and
interstitial fluid and between interstitial fluid and
body cells
© 2014 Pearson Education, Inc.
Figure 34.3b
(b) A closed circulatory system
Blood
Heart
Interstitial
fluid
Branch vessels
in each organ
Dorsal vessel
(main heart)
Auxiliary
hearts
© 2014 Pearson Education, Inc.
Ventral vessels
Organization of Vertebrate Circulatory Systems
 Humans and other vertebrates have a closed
circulatory system called the cardiovascular
system
 The three main types of blood vessels are arteries,
veins, and capillaries
 Blood flow is one-way in these vessels
© 2014 Pearson Education, Inc.
 Arteries branch into arterioles and carry blood
away from the heart to capillaries
 Networks of capillaries called capillary beds are
the sites of chemical exchange between the blood
and interstitial fluid
 Venules converge into veins and return blood from
capillaries to the heart
© 2014 Pearson Education, Inc.
 Arteries and veins are distinguished by the direction
of blood flow, not by O2 content
 Vertebrate hearts contain two or more chambers
 Blood enters through an atrium and is pumped out
through a ventricle
© 2014 Pearson Education, Inc.
Single Circulation
 Bony fishes, rays, and sharks have single circulation
with a two-chambered heart
 In single circulation, blood leaving the heart
passes through two capillary beds before returning
© 2014 Pearson Education, Inc.
Figure 34.4
(a) Single circulation: fish
Gill capillaries
(b) Double circulation:
amphibian
Lung
and skin
capillaries
A
Right
Vein
Pulmonary
circuit
Pulmocutaneous
circuit
Artery
Heart:
Atrium (A)
Ventricle (V)
(c) Double circulation:
mammal
Lung
capillaries
A
V
A
Left
Right
V
A
V
Left
Systemic
capillaries
Body capillaries
Key
Oxygen-rich blood
Oxygen-poor blood
© 2014 Pearson Education, Inc.
Systemic circuit
Systemic
capillaries
Systemic circuit
Figure 34.4a
(a) Single circulation: fish
Gill capillaries
Artery
Heart:
Atrium (A)
Ventricle (V)
Vein
Body capillaries
Key
Oxygen-rich blood
Oxygen-poor blood
© 2014 Pearson Education, Inc.
Double Circulation
 Amphibians, reptiles, and mammals have double
circulation
 Oxygen-poor and oxygen-rich blood is pumped
separately from the right and left sides of the heart
 Having both pumps within a heart simplifies
coordination of the pumping cycle
© 2014 Pearson Education, Inc.
Figure 34.4b
(b) Double circulation:
amphibian
Pulmocutaneous
circuit
Lung
and skin
capillaries
A
Right
A
Left
V
Systemic
capillaries
Systemic circuit
Key
Oxygen-rich blood
Oxygen-poor blood
© 2014 Pearson Education, Inc.
Figure 34.4c
(c) Double circulation:
mammal
Pulmonary
circuit
Lung
capillaries
A
V
Right
A
V
Left
Systemic
capillaries
Systemic circuit
Key
Oxygen-rich blood
Oxygen-poor blood
© 2014 Pearson Education, Inc.
 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 through
the lungs and skin
 Oxygen-rich blood delivers oxygen through the
systemic circuit
 Double circulation maintains higher blood pressure
in the organs than does single circulation
© 2014 Pearson Education, Inc.
Evolutionary Variation in Double Circulation
 Some vertebrates with double circulation are
intermittent breathers
 These animals have adaptations that enable the
circulatory system temporarily to bypass the lungs
© 2014 Pearson Education, Inc.
 Frogs and other amphibians have a threechambered heart: two atria and one ventricle
 The ventricle pumps blood into a forked artery that
splits the ventricle’s output into the pulmocutaneous
circuit and the systemic circuit
 When underwater, blood flow to the lungs is nearly
shut off
© 2014 Pearson Education, Inc.
 Turtles, snakes, and lizards have a three-chambered
heart: two atria and one ventricle
 Their circulatory system allows control of relative
amounts of blood flowing to the lungs and body
 In alligators, caimans, and other crocodilians a
septum divides the ventricle
 A connection to atrial valves can temporarily shunt
blood away from the lungs, as needed
© 2014 Pearson Education, Inc.
 Mammals and birds have a four-chambered heart
with two atria and two ventricles
 The left side of the heart pumps and receives only
oxygen-rich blood, while the right side receives and
pumps only oxygen-poor blood
 There is no mechanism to vary relative blood flow to
the lungs and body
 Mammals and birds are endotherms and require
more O2 than ectotherms
© 2014 Pearson Education, Inc.
Concept 34.2: Coordinated cycles of heart
contraction drive double circulation in mammals
 The mammalian cardiovascular system meets the
body’s continuous demand for O2
© 2014 Pearson Education, Inc.
Mammalian Circulation
 Blood begins its flow with the right ventricle pumping
blood to the lungs via the pulmonary arteries
 The blood loads O2 and unloads CO2 in the capillary
beds of the lungs
 Oxygen-rich blood from the lungs enters the heart at
the left atrium via the pulmonary veins and is
pumped through the aorta to the body tissues by the
left ventricle
© 2014 Pearson Education, Inc.
 The aorta provides blood to the heart through the
coronary arteries
 Diffusion of O2 and CO2 takes place in the capillary
beds throughout the body
 Blood returns to the heart through the superior vena
cava (blood from head, neck, and forelimbs) and
inferior vena cava (blood from trunk and hind limbs)
 The superior vena cava and inferior vena cava flow
into the right atrium
Animation: Path of Blood Flow
© 2014 Pearson Education, Inc.
Figure 34.5
Superior
vena cava
Capillaries of
head and
forelimbs
7
Pulmonary
artery
Pulmonary artery
Capillaries
of left lung
Aorta
9
Capillaries
of right lung
6
2
3
3
4
11
Pulmonary
vein
Right atrium
1
Pulmonary
vein
Left atrium
5
10
Left ventricle
Right ventricle
Inferior vena cava
Aorta
8
© 2014 Pearson Education, Inc.
Capillaries of
abdominal organs
and hind limbs
The Mammalian Heart: A Closer Look
 A closer look at the mammalian heart provides a
better understanding of double circulation
 When the heart contracts, it pumps blood; when it
relaxes, its chambers fill with blood
 One complete sequence of pumping and filling is
called the cardiac cycle
© 2014 Pearson Education, Inc.
 Atria have relatively thin walls and serve as
collection chambers for blood returning to the heart
 The ventricles are more muscular and contract much
more forcefully than the atria
 The volume of blood each ventricle pumps per
minute is called the cardiac output
© 2014 Pearson Education, Inc.
Figure 34.6
Aorta
Pulmonary artery
Pulmonary
artery
Right
atrium
Left
atrium
Semilunar
valve
Semilunar
valve
Atrioventricular
(AV) valve
Atrioventricular
(AV) valve
© 2014 Pearson Education, Inc.
Right
ventricle
Left
ventricle
Figure 34.7-1
1 Atrial and
ventricular
diastole
0.4
sec
© 2014 Pearson Education, Inc.
Figure 34.7-2
2 Atrial systole and
ventricular diastole
1 Atrial and
ventricular
diastole
0.1
sec
0.4
sec
© 2014 Pearson Education, Inc.
Figure 34.7-3
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
© 2014 Pearson Education, Inc.
 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
 Cardiac output depends on both the heart rate and
stroke volume
© 2014 Pearson Education, Inc.
 Four valves prevent backflow of blood in the heart
 The atrioventricular (AV) valves separate each
atrium and ventricle
 The semilunar valves control blood flow to the
aorta and the pulmonary artery
© 2014 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
© 2014 Pearson Education, Inc.
Maintaining the Heart’s Rhythmic Beat
 Some cardiac muscle cells are autorhythmic,
meaning they contract without any signal from the
nervous system
 The sinoatrial (SA) node, or pacemaker, sets the
rate and timing at which all other cardiac muscle
cells contract
 The SA node produces electrical impulses that
spread rapidly through the heart and can be
recorded as an electrocardiogram (ECG or EKG)
© 2014 Pearson Education, Inc.
Figure 34.8-1
1 Signals (yellow)
from SA node
spread
through atria.
SA node
(pacemaker)
ECG
© 2014 Pearson Education, Inc.
Figure 34.8-2
1 Signals (yellow)
from SA node
spread
through atria.
SA node
(pacemaker)
ECG
© 2014 Pearson Education, Inc.
2 Signals are
delayed
at AV node.
AV
node
Figure 34.8-3
1 Signals (yellow)
from SA node
spread
through atria.
SA node
(pacemaker)
ECG
© 2014 Pearson Education, Inc.
2 Signals are
delayed
at AV node.
AV
node
3 Bundle
branches
pass signals
to heart apex.
Bundle
branches
Heart
apex
Figure 34.8-4
1 Signals (yellow)
from SA node
spread
through atria.
SA node
(pacemaker)
ECG
© 2014 Pearson Education, Inc.
2 Signals are
delayed
at AV node.
AV
node
3 Bundle
branches
pass signals
to heart apex.
Bundle
branches
Heart
apex
4 Signals
spread
throughout
ventricles.
Purkinje
fibers
 Impulses from the SA node travel to the
atrioventricular (AV) node
 At the AV node, the impulses are delayed and
then travel to the Purkinje fibers that make the
ventricles contract
© 2014 Pearson Education, Inc.
 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
© 2014 Pearson Education, Inc.
Concept 34.3: Patterns of blood pressure and flow
reflect the structure and arrangement of blood
vessels
 The physical principles that govern movement of
water in plumbing systems also apply to the
functioning of animal circulatory systems
© 2014 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
to blood flow
© 2014 Pearson Education, Inc.
 Capillaries have thin walls, the endothelium and its
basal lamina, to facilitate the exchange of
substances
 Arteries and veins have an endothelium, smooth
muscle, and connective tissue
 Arteries have thicker walls than veins to
accommodate the high pressure of blood pumped
from the heart
© 2014 Pearson Education, Inc.
Figure 34.9
LM
Artery Vein
Red blood
cells
100 m
Valve
Basal lamina
Endothelium
Smooth
muscle
Connective
tissue
Endothelium
Smooth
muscle
Connective
tissue
Capillary
Artery
Vein
Capillary
© 2014 Pearson Education, Inc.
15 m
Red blood cell
Venule
LM
Arteriole
Figure 34.9a
Valve
Connective
tissue
Endothelium
Basal lamina
Smooth
muscle
Smooth
muscle
Endothelium
Connective
tissue
Capillary
Artery
Vein
Arteriole
© 2014 Pearson Education, Inc.
Venule
Figure 34.9b
LM
Artery Vein
Red blood
cells
© 2014 Pearson Education, Inc.
100 m
Capillary
© 2014 Pearson Education, Inc.
LM
Red blood cell
15 m
Figure 34.9c
Blood Flow Velocity
 Blood vessel diameter influences blood flow
 Velocity of blood flow is slowest in the capillary
beds, as a result of the high resistance and large
total cross-sectional area
 Blood flow in capillaries is necessarily slow for
exchange of materials
© 2014 Pearson Education, Inc.
4,000
2,000
0
40
20
0
120
80
© 2014 Pearson Education, Inc.
Venae
cavae
Veins
Arteries
40 Diastolic
pressure
0
Arterioles
Capillaries
Venules
Systolic
pressure
Aorta
Pressure
(mm Hg)
Velocity
(cm/sec)
Area (cm2)
Figure 34.10
Blood Pressure
 Blood flows from areas of higher pressure to areas
of lower pressure
 Blood pressure exerts a force in all directions
© 2014 Pearson Education, Inc.
Changes in Blood Pressure During the Cardiac
Cycle
 Systole is the contraction phase of the cardiac cycle
 Pressure at the time of ventricle contraction is called
systolic pressure
 Diastole is the the relaxation phase of the cardiac
cycle; diastolic pressure is lower than systolic
© 2014 Pearson Education, Inc.
Maintenance of Blood Pressure
 Blood pressure is determined by cardiac output and
peripheral resistance due to constriction of
arterioles
 Vasoconstriction is the contraction of smooth
muscle in arteriole walls; it increases blood pressure
 Vasodilation is the relaxation of smooth muscles in
the arterioles; it causes blood pressure to fall
© 2014 Pearson Education, Inc.
 Vasoconstriction and vasodilation help maintain
adequate blood flow as the body’s demands change
 Nitric oxide is a major inducer of vasodilation
 The peptide endothelin is an important inducer of
vasoconstriction
© 2014 Pearson Education, Inc.
 Fainting is caused by inadequate blood flow to the
head
 Animals with long necks require a higher systolic
pressure to pump blood against gravity
 Gravity is a consideration for blood flow in veins,
particularly in the legs
 One-way valves in veins prevent backflow of blood
 Blood returns to the heart through contraction of
smooth muscle in the walls of veins and venules and
by contraction of skeletal muscles
© 2014 Pearson Education, Inc.
Figure 34.11
Direction of blood
flow in vein
(toward heart)
Valve (open)
Skeletal muscle
Valve (closed)
© 2014 Pearson Education, Inc.
Capillary Function
 Blood flows through only 5–10% of the body’s
capillaries at a time
 Capillaries in major organs are usually filled to
capacity
 Blood supply varies in many other sites
© 2014 Pearson Education, Inc.
 Two mechanisms alter blood flow in capillary beds
 Vasoconstriction or vasodilation of the arteriole that
supplies a capillary bed
 Precapillary sphincters, rings of smooth muscle at the
capillary bed entrance, open and close to regulate
passage of blood
 Critical exchange of substances takes place across
the thin walls of the capillaries
© 2014 Pearson Education, Inc.
 Blood pressure tends to drive fluid out of the
capillaries
 The difference in solute concentration between blood
and interstitial fluid (the blood’s osmotic pressure)
opposes fluid movement from the capillaries
 Blood pressure is usually greater than osmotic
pressure
 Net loss of fluid from capillaries occurs in regions
where blood pressure is highest
© 2014 Pearson Education, Inc.
Fluid Return by the Lymphatic System
 The lymphatic system returns fluid, called lymph,
that leaks out from the capillary beds
 Lymph has a very similar composition to interstitial
fluid
 The lymphatic system drains into veins in the neck
 Valves in lymph vessels prevent the backflow of
fluid
© 2014 Pearson Education, Inc.
Figure 34.12
Blood
capillary
Interstitial
fluid
Adenoid
Tonsils
Lymphatic
vessels
Thymus
(immune
system)
Tissue cells
Lymphatic
vessel
Spleen
Lymph
nodes
Appendix
(cecum)
Peyer’s patches
(small intestine)
© 2014 Pearson Education, Inc.
Lymphatic
vessel
Lymph node
Masses of
defensive
cells
 Lymph vessels have valves to prevent backflow
 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
 The lymphatic system also plays a role in harmful
immune responses, such as those responsible for
asthma
© 2014 Pearson Education, Inc.
Concept 34.4: Blood components function in
exchange, transport, and defense
 With open circulation, the fluid that is pumped
comes into direct contact with all cells and has
the same composition as interstitial fluid
 The closed circulatory systems of vertebrates
contain blood, which can be much more highly
specialized
© 2014 Pearson Education, Inc.
Blood Composition and Function
 Blood is a connective tissue consisting of cells
suspended in a liquid matrix called plasma
 The cellular elements occupy about 45% of the
volume of blood
Video: Leukocyte Rolling
© 2014 Pearson Education, Inc.
Figure 34.13
Cellular elements 45%
Plasma 55%
Constituent
Water
Ions (blood
electrolytes)
Sodium
Potassium
Calcium
Magnesium
Chloride
Bicarbonate
Major functions
Solvent for
carrying other
substances
Osmotic balance,
pH buffering,
and regulation
of membrane
permeability
Functions
5,000–10,000
Defense
and
immunity
Separated
blood
elements
Lymphocytes
Basophils
Neutrophils
Osmotic balance,
pH buffering
Fibrinogen
Clotting
Immunoglobulins
(antibodies)
Defense
Substances transported by blood
Nutrients (such as glucose, fatty
acids, vitamins)
Waste products of metabolism
Respiratory gases (O2 and CO2)
Hormones
© 2014 Pearson Education, Inc.
Leukocytes (white blood cells)
per L (mm3)
of blood
Eosinophils
Plasma proteins
Albumin
Number
Cell type
Monocytes
Platelets
Erythrocytes (red blood cells)
250,000–400,000
5,000,000–
6,000,000
Blood
clotting
Transport
of O2 and
some CO2
Figure 34.13a
Plasma 55%
Major functions
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
Osmotic balance, pH buffering
Fibrinogen
Clotting
Immunoglobulins
(antibodies)
Defense
Substances transported by blood
Nutrients (such as glucose, fatty acids, vitamins)
Waste products of metabolism
Respiratory gases (O2 and CO2)
Hormones
© 2014 Pearson Education, Inc.
Figure 34.13b
Cellular elements 45%
Number
Cell type
per L (mm3) of blood
Leukocytes (white blood cells)
5,000–10,000
Functions
Defense and
immunity
Lymphocytes
Basophils
Eosinophils
Neutrophils
Monocytes
Platelets
Erythrocytes (red blood cells)
© 2014 Pearson Education, Inc.
250,000–400,000
5,000,000–6,000,000
Blood clotting
Transport of O2 and
some CO2
Plasma
 Blood plasma is about 90% water
 Among its solutes are inorganic salts in the form of
dissolved ions, sometimes called electrolytes
 Plasma proteins influence blood pH, osmotic
pressure, and viscosity
 Particular plasma proteins function in lipid transport,
immunity, and blood clotting
© 2014 Pearson Education, Inc.
Cellular Elements
 Blood contains two classes of cells
 Red blood cells (erythrocytes) transport O2
 White blood cells (leukocytes) function in defense
 Platelets, a third cellular element, are fragments of
cells that are involved in clotting
© 2014 Pearson Education, Inc.
Figure 34.14
Stem cells
(in bone marrow)
Lymphoid
stem cells
Myeloid
stem cells
B cells T cells
Erythrocytes
Neutrophils
Basophils
Lymphocytes
Monocytes
© 2014 Pearson Education, Inc.
Platelets
Eosinophils
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
© 2014 Pearson Education, Inc.
 Sickle-cell disease is caused by abnormal
hemoglobin that polymerizes into aggregates
 The aggregates can distort an erythrocyte into a
sickle shape
© 2014 Pearson Education, Inc.
 Through a person’s life, multipotent stem cells
replace the worn-out cellular elements of blood
 Erythrocytes circulate for about 120 days before
they are replaced
 Stem cells that produce red blood cells and platelets
are located in red marrow of bones like the ribs,
vertebrae, sternum, and pelvis
© 2014 Pearson Education, Inc.
Leukocytes
 There are five major types of white blood cells, or
leukocytes
 They function in defense by engulfing bacteria and
debris or by mounting immune responses against
foreign substances
 They are found both in and outside of the circulatory
system
© 2014 Pearson Education, Inc.
Platelets
 Platelets are fragments of cells and function in
blood clotting
© 2014 Pearson Education, Inc.
Blood Clotting
 Coagulation is the formation of a solid clot from
liquid blood
 A cascade of complex reactions converts inactive
fibrinogen to fibrin, which forms the framework of a
clot
 A blood clot formed within a blood vessel is called a
thrombus and can block blood flow
© 2014 Pearson Education, Inc.
Figure 34.15
2
1
3
Collagen
fibers
Platelet
Platelet
plug
Clotting factors from:
Platelets
Damaged cells
Plasma (factors include calcium, vitamin K)
Enzymatic cascade
Prothrombin
Thrombin
Fibrinogen
© 2014 Pearson Education, Inc.
Fibrin
Fibrin clot
Fibrin clot
formation
Red blood cell
5 m
Figure 34.15a
2
1
3
Collagen
fibers
Platelet
Platelet
plug
Clotting factors from:
Platelets
Damaged cells
Plasma (factors include calcium, vitamin K)
Enzymatic cascade
Prothrombin
Thrombin
Fibrinogen
© 2014 Pearson Education, Inc.
Fibrin
Fibrin clot
Fibrin clot
formation
Figure 34.15b
Fibrin
clot
Red blood cell
© 2014 Pearson Education, Inc.
5 m
Cardiovascular Disease
 Cardiovascular diseases are disorders of the heart
and the blood vessels
 Cardiovascular diseases account for more than half
the deaths in the United States
 Cholesterol, a steroid, helps maintain normal
membrane fluidity
© 2014 Pearson Education, Inc.
 Low-density lipoprotein (LDL) delivers cholesterol
to cells for membrane production
 High-density lipoprotein (HDL) scavenges excess
cholesterol for return to the liver
 Risk for heart disease increases with a high LDL to
HDL ratio
 Inflammation is also a factor in cardiovascular
disease
© 2014 Pearson Education, Inc.
Atherosclerosis, Heart Attacks, and Stroke
 One type of cardiovascular disease, atherosclerosis,
is caused by the buildup of fatty deposits within
arteries
 A fatty deposit is called a plaque; as it grows, the
artery walls become thick and stiff and the obstruction
of the artery increases
© 2014 Pearson Education, Inc.
Figure 34.16
Endothelium
Lumen
Blood clot
Plaque
© 2014 Pearson Education, Inc.
 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 may cause chest pain
© 2014 Pearson Education, Inc.
Risk Factors and Treatment of Cardiovascular
Disease
 A high LDL to HDL ratio increases the risk of
cardiovascular disease
 The proportion of LDL relative to HDL is increased by
smoking and consumption of trans fats and
decreased by exercise
 Drugs called statins reduce LDL levels and risk of
heart attacks
© 2014 Pearson Education, Inc.
 Inflammation plays a role in atherosclerosis and
thrombus formation
 Aspirin inhibits inflammation and reduces the risk of
heart attacks and stroke
 Hypertension (high blood pressure) contributes to
the risk of heart attack and stroke
 Hypertension can be reduced by dietary changes,
exercise, medication, or some combination of these
© 2014 Pearson Education, Inc.
Concept 34.5: Gas exchange occurs across
specialized respiratory surfaces
 Gas exchange is the uptake of molecular O2 from
the environment and the discharge of CO2 to the
environment
© 2014 Pearson Education, Inc.
Partial Pressure Gradients in Gas Exchange
 Partial pressure is the pressure exerted by a
particular gas in a mixture of gases
 For example, the atmosphere is 21% O2, by volume,
so the partial pressure of O2 (PO2) is 0.21  the
atmospheric pressure
© 2014 Pearson Education, Inc.
 Partial pressures also apply to gases dissolved in
liquid, such as water
 When water is exposed to air, an equilibrium is
reached in which the partial pressure of each gas is
the same in the water and the air
 A gas always undergoes net diffusion from a region
of higher partial pressure to a region of lower partial
pressure
© 2014 Pearson Education, Inc.
Respiratory Media
 O2 is plentiful in air, and breathing air is relatively
easy
 In a given volume, there is less O2 available in water
than in air
 Obtaining O2 from water requires greater energy
expenditure than air breathing
 Aquatic animals have a variety of adaptations to
improve efficiency in gas exchange
© 2014 Pearson Education, Inc.
Figure 34.17
Coelom
Gills
Parapodium (functions as gill)
(a) Marine worm
© 2014 Pearson Education, Inc.
Tube foot
(b) Sea star
Figure 34.17a
(a) Marine worm
© 2014 Pearson Education, Inc.
Figure 34.17b
(b) Sea star
© 2014 Pearson Education, Inc.
Respiratory Surfaces
 Gas exchange across respiratory surfaces takes
place by diffusion
 Respiratory surfaces tend to be large and thin and
are always moist
 Respiratory surfaces vary by animal and can include
the skin, gills, tracheae, and lungs
© 2014 Pearson Education, Inc.
Gills in Aquatic Animals
 Gills are outfoldings of the body that create a large
surface area for gas exchange
 Ventilation is the movement of the respiratory
medium over the respiratory surface
 Ventilation maintains the necessary partial pressure
gradients of O2 and CO2 across the gills
© 2014 Pearson Education, Inc.
 Aquatic animals move through water or move water
over their gills for ventilation
 Fish gills use a countercurrent exchange system,
where blood flows in the opposite direction to water
passing over the gills
 Blood is always less saturated with O2 than the water
it meets
 Countercurrent exchange mechanisms are
remarkably efficient
© 2014 Pearson Education, Inc.
Figure 34.18
O2-poor blood
Gill
arch
Lamella
O2-rich blood
Blood
vessels
Gill arch
Water
Operculum
flow
Water flow
Blood flow
Countercurrent exchange
PO2 (mm Hg) in water
Gill filaments
© 2014 Pearson Education, Inc.
Net
diffusion
of O2
150 120 90 60
30
140 110 80 50
30
PO2 (mm Hg)
in blood
Tracheal Systems in Insects
 The tracheal system of insects consists of a
network of air tubes that branch throughout the
body
 The tracheal system can transport O2 and CO2
without the participation of the animal’s open
circulatory system
 Larger insects must ventilate their tracheal system
to meet O2 demands
© 2014 Pearson Education, Inc.
Figure 34.19
Muscle fiber
2.5 m
Tracheoles Mitochondria
Tracheae
Air sacs
Body
cell
Tracheole
Air
sac
Trachea
External opening
© 2014 Pearson Education, Inc.
Air
Figure 34.19a
Muscle fiber
2.5 m
Tracheoles Mitochondria
© 2014 Pearson Education, Inc.
Lungs
 Lungs are an infolding of the body surface, usually
divided into numerous pockets
 The circulatory system (open and closed) transports
gases between the lungs and the rest of the body
 The use of lungs for gas exchange varies among
vertebrates that lack gills
© 2014 Pearson Education, Inc.
Mammalian Respiratory Systems: A Closer Look
 A system of branching ducts conveys air to the lungs
 Air inhaled through the nostrils is warmed,
humidified, and sampled for odors
 The pharynx directs air to the lungs and food to the
stomach
 Swallowing tips the epiglottis over the glottis in the
pharynx to prevent food from entering the trachea
© 2014 Pearson Education, Inc.
 Air passes through the pharynx, larynx, trachea,
bronchi, and bronchioles to the alveoli, where gas
exchange occurs
 Exhaled air passes over the vocal cords in the
larynx to create sounds
 Cilia and mucus line the epithelium of the air ducts
and move particles up to the pharynx
 This “mucus escalator” cleans the respiratory
system and allows particles to be swallowed into the
esophagus
© 2014 Pearson Education, Inc.
 Gas exchange takes place in alveoli, air sacs at the
tips of bronchioles
 Oxygen diffuses through the moist film of the
epithelium and into capillaries
 Carbon dioxide diffuses from the capillaries across
the epithelium and into the air space
Animation: Gas Exchange
© 2014 Pearson Education, Inc.
Figure 34.20
Branch of
pulmonary vein
(oxygen-rich
blood)
Branch of pulmonary
artery (oxygen-poor
blood)
Terminal
bronchiole
Nasal
cavity
Pharynx
Left
lung
Larynx
(Esophagus)
Alveoli
Trachea
Right lung
Capillaries
50 m
Bronchus
Bronchiole
Diaphragm
(Heart)
Dense capillary bed
enveloping alveoli
(SEM)
© 2014 Pearson Education, Inc.
Figure 34.20a
Nasal
cavity
Pharynx
Left
lung
Larynx
(Esophagus)
Trachea
Right lung
Bronchus
Bronchiole
Diaphragm
(Heart)
© 2014 Pearson Education, Inc.
Figure 34.20b
Branch of
pulmonary vein
(oxygen-rich
blood)
Branch of pulmonary
artery (oxygen-poor
blood)
Terminal
bronchiole
Alveoli
Capillaries
© 2014 Pearson Education, Inc.
Figure 34.20c
50 m
Dense capillary bed
enveloping alveoli (SEM)
© 2014 Pearson Education, Inc.
 Alveoli lack cilia and are susceptible to contamination
 Secretions called surfactants coat the surface of
the alveoli
 Preterm babies lack surfactant and are vulnerable to
respiratory distress syndrome; treatment is provided
by artificial surfactants
© 2014 Pearson Education, Inc.
Figure 34.21
Surface tension (dynes/cm)
Results
40
30
20
10
RDS deaths
0
Deaths from
other causes
(n  9)
(n  0)
<1,200 g
(n  29) (n  9)
>1,200 g
Body mass of infant
© 2014 Pearson Education, Inc.
Concept 34.6: Breathing ventilates the lungs
 The process that ventilates the lungs is breathing,
the alternate inhalation and exhalation of air
© 2014 Pearson Education, Inc.
 An amphibian such as a frog ventilates its lungs by
positive pressure breathing, which forces air down
the trachea
 Birds have eight or nine air sacs that function as
bellows that keep air flowing through the lungs
 Air passes through the lungs of birds in one direction
only
 Passage of air through the entire system—lungs and
air sacs—requires two cycles in inhalation and
exhalation
© 2014 Pearson Education, Inc.
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
Animation: Gas Exchange
© 2014 Pearson Education, Inc.
Figure 34.22
Rib cage
expands as
rib muscles
contract.
Air
inhaled.
Rib cage gets
smaller as
rib muscles
relax.
Air
exhaled.
Lung
Diaphragm
1 Inhalation:
Diaphragm contracts
(moves down).
© 2014 Pearson Education, Inc.
2 Exhalation:
Diaphragm relaxes
(moves up).
 The maximum tidal volume is the vital capacity
 After exhalation, a residual volume of air remains
in the lungs
 Each inhalation mixes fresh air with oxygen-depleted
residual air
 As a result, the maximum PO2 in alveoli is
considerably less than in the atmosphere
© 2014 Pearson Education, Inc.
Control of Breathing in Humans
 In humans, the main breathing control center
consists of neural circuits in the medulla oblongata,
near the base of the brain
 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
© 2014 Pearson Education, Inc.
Figure 34.23-1
Homeostasis:
Blood pH of about 7.4
Stimulus:
Rising level of CO2
in tissues lowers
blood pH.
© 2014 Pearson Education, Inc.
Figure 34.23-2
Homeostasis:
Blood pH of about 7.4
Stimulus:
Rising level of CO2
in tissues lowers
blood pH.
Carotid
arteries
Sensor/control
center:
Cerebrospinal
fluid
Medulla
oblongata
© 2014 Pearson Education, Inc.
Aorta
Figure 34.23-3
Homeostasis:
Blood pH of about 7.4
Response:
Signals from
medulla to 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
© 2014 Pearson Education, Inc.
Aorta
Figure 34.23-4
Homeostasis:
Blood pH of about 7.4
CO2 level
decreases.
Response:
Signals from
medulla to 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
© 2014 Pearson Education, Inc.
Aorta
 Sensors in the aorta and carotid arteries monitor O2
and CO2 concentrations in the blood
 These sensors exert secondary control over
breathing
© 2014 Pearson Education, Inc.
Concept 34.7: 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
© 2014 Pearson Education, Inc.
Coordination of Circulation and Gas Exchange
 Blood arriving in the lungs has a low PO2 and a high
PCO2 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
 Specialized carrier proteins play a vital role in this
process
© 2014 Pearson Education, Inc.
Animation: CO2 Blood to Lungs
Animation: CO2 Tissues to Blood
Animation: O2 Blood to Tissues
Animation: O2 Lungs to Blood
© 2014 Pearson Education, Inc.
Figure 34.24
120 27
Inhaled air
Exhaled air
160 0.2
O2 CO2
O2 CO2
Alveolar
epithelial
cells
CO2
O2
Alveolar
spaces
Alveolar
capillaries
Pulmonary
veins
Pulmonary
arteries
40 45
104 40
O2 CO2
O2 CO2
Systemic
veins
Systemic
arteries
Systemic
capillaries
Heart
CO2
O2
<40 >45
O2 CO2
Body tissue
cells
© 2014 Pearson Education, Inc.
Respiratory Pigments
 Respiratory pigments circulate in blood or
hemolymph and greatly increase the amount of
oxygen that is transported
 A variety of respiratory pigments have evolved
among animals
 These mainly consist of a metal bound to a protein
© 2014 Pearson Education, Inc.
 The respiratory pigment of almost all vertebrates
and many invertebrates is hemoglobin
 A single hemoglobin molecule can carry four
molecules of O2, one molecule for each ironcontaining heme group
 Hemoglobin binds oxygen reversibly, loading it in
the gills or lungs and releasing it in other parts of
the body
© 2014 Pearson Education, Inc.
Figure 34.UN01
Iron
Heme
Hemoglobin
© 2014 Pearson Education, Inc.
 Hemoglobin binds O2 cooperatively
 When O2 binds one subunit, the others change shape
slightly, resulting in their increased affinity for oxygen
 When one subunit releases O2, the others release
their bound O2 more readily
 Cooperativity can be demonstrated by the dissociation
curve for hemoglobin
© 2014 Pearson Education, Inc.
100
O2 unloaded
to tissues
at rest
80
O2 unloaded
to tissues
during exercise
60
40
20
0
0
20
Tissues during
exercise
40
60
Tissues
at rest
PO2 (mm Hg)
100
80
Lungs
(a) PO2 and hemoglobin dissociation
at pH 7.4
© 2014 Pearson Education, Inc.
O2 saturation of hemoglobin (%)
O2 saturation of hemoglobin (%)
Figure 34.25
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
80
PO2 (mm Hg)
(b) pH and hemoglobin dissociation
100
O2 saturation of hemoglobin (%)
Figure 34.25a
100
O2 unloaded
to tissues
at rest
80
O2 unloaded
to tissues
during exercise
60
40
20
0
0
20
Tissues during
exercise
40
60
Tissues
at rest
PO2 (mm Hg)
80
100
Lungs
(a) PO2 and hemoglobin dissociation
at pH 7.4
© 2014 Pearson Education, Inc.
 CO2 produced during cellular respiration lowers
blood pH and decreases the affinity of hemoglobin
for O2; this is called the Bohr shift
 Hemoglobin also assists in preventing harmful
changes in blood pH and plays a minor role in CO2
transport
© 2014 Pearson Education, Inc.
O2 saturation of hemoglobin (%)
Figure 34.25b
100
pH 7.4
80
pH 7.2
60
Hemoglobin
retains less
O2 at lower pH
(higher CO2
concentration
40
20
0
0
20
40
60
80
PO2 (mm Hg)
(b) pH and hemoglobin dissociation
© 2014 Pearson Education, Inc.
100
Carbon Dioxide Transport
 Most of the CO2 from respiring cells diffuses into the
blood and is transported in blood plasma, bound to
hemoglobin or as bicarbonate ions (HCO3–)
© 2014 Pearson Education, Inc.
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
© 2014 Pearson Education, Inc.
 Deep-diving air breathers can store large amounts
of O2
 Oxygen can be stored 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
© 2014 Pearson Education, Inc.
Percent of individuals
Figure 34.UN02a
30
20
10
0
0
50
100
200
150
250
Plasma LDL cholesterol (mg/dL)
Individuals with an inactivating mutation in one copy
of PCSK9 gene (study group)
© 2014 Pearson Education, Inc.
300
Percent of individuals
Figure 34.UN02b
30
20
10
0
0
50
100
200
150
250
Plasma LDL cholesterol (mg/dL)
Individuals with two functional copies of PCSK9 gene
(control group)
© 2014 Pearson Education, Inc.
300
Figure 34.UN03
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
© 2014 Pearson Education, Inc.
O2 saturation of
hemoglobin (%)
Figure 34.UN04
100
80
60
Fetus
Mother
40
20
0
0 20 40 60 80 100
PO2 (mm Hg)
© 2014 Pearson Education, Inc.