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Circulation and Respiration
 Unifying concepts of animal circulation
 The human cardiovascular system
 Unifying concepts of animal respiration
 The human respiratory system
UNIFYING CONCEPTS OF ANIMAL CIRCULATION
• Every organism must exchange materials with its
environment, relying upon
– diffusion, the spontaneous movement of
molecules from an area of higher concentration to
an area of lower concentration, and
– a circulatory system, which facilitates the
exchange of materials for all but the simplest
animals.
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Open and Closed Circulatory Systems
• Circulatory systems typically consist of a
– central pump,
– vascular system, and
– circulating fluid.
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Open and Closed Circulatory Systems
• In an open circulatory system,
– the heart pumps blood into large open-ended
vessels and
– fluid circulates freely among cells.
• Open circulatory systems are found in many
invertebrates, including
– arthropods and
– most molluscs.
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Open and Closed Circulatory Systems
• In a closed circulatory system, blood
– stays within a set of tubes and
– is distinct from the interstitial fluid, the fluid that
fills the spaces around cells.
• Closed circulatory systems are found in
– many invertebrates, including earthworms and
octopuses, and
– vertebrates.
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Figure 23.1
Vessels
Interstitial fluid
Vessels
Capillaries
Heart
Heart
Circulating fluid
Arteriole Capillaries
Tubular
heart
Artery
(O2-rich
blood)
Venule
Vein
Vessels
(a) Open circulatory system
Atrium
Ventricle
Artery
(O2-poor blood)
(b) Closed circulatory system
Heart
Open and Closed Circulatory Systems
• The cardiovascular system of vertebrates
consists of the
– heart and
– blood vessels.
• In the heart,
– the atrium receives blood and
– the ventricle pumps blood away from the heart.
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Open and Closed Circulatory Systems
• Blood is confined to three main types of blood
vessels:
1. Arteries carry blood away from the heart into
smaller arterioles as they approach the organs.
2. Capillaries are the site of exchange between
blood and interstitial fluid.
3. Venules collect blood from the capillaries and
converge to form veins, which return blood back
to the heart.
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THE HUMAN CARDIOVASCULAR SYSTEM
• In the human cardiovascular system, there are
three main components:
– 1. the central pump is the heart,
– 2. the vascular system is the blood vessels, and
– 3. the circulating fluid is the blood.
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The Path of Blood
• Humans and other terrestrial vertebrates have a
double circulation system consisting of
– a pulmonary circuit between the heart and lungs
and
– a systemic circuit between the heart and the rest
of the body.
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Figure 23.2
CO2
O2
CO2
CO2
Lung
Lung
O2
O2
Heart
O2-rich blood
O2
O2-poor blood
CO2
(a) Pulmonary circuit
(b) Systemic circuit
The Path of Blood
• One complete trip through the human
cardiovascular system
– takes about one minute and
– requires two passes through the heart.
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Figure 23.3-7
Know
this!
Capillaries of
head, chest,
and arms
Superior
vena cava
Pulmonary
artery
Pulmonary
artery
Aorta
Capillaries
of right lung
3
4
5
Pulmonary vein
Right atrium
Right ventricle
Capillaries
of left lung
3
4
6
1
5
2
7
Pulmonary vein
Left atrium
Left ventricle
Inferior
vena cava
O2-rich blood
O2-poor blood
Capillaries of
abdominal region
and legs
How the Heart Works
• The human heart
– is a muscular organ about the size of a fist,
– is located under the breastbone, and
– has four chambers.
• The path of blood flow through the human heart
functions as two pumps moving blood between
– the heart and lungs and
– the heart and the rest of the body.
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Figure 23.4
To body
O2-rich blood
O2-poor blood
Know this!
From
body
Right
lung
Left
lung
Right atrium
Left atrium
Valves
Valves
Right
ventricle
From body
Left
ventricle
The Cardiac Cycle
• The heart relaxes and contracts throughout our
lives.
– Diastole is the relaxation phase of the heart
cycle.
– Systole is the contraction phase.
• A heart murmur is a sound that may indicate a
defect in one or more of the heart valves.
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Figure 23.5-3
2 Atria contract. Blood is
forced into ventricles.
1 Heart is relaxed.
Blood flows in.
0.1
sec
0.8
sec
DIASTOLE
0.3
sec
0.4
sec
3 Ventricles contract.
Blood is pumped out.
SYSTOLE
The Pacemaker and the Control of Heart Rate
• The pacemaker, or SA (sinoatrial) node,
– sets the tempo of the heartbeat and
– is composed of specialized muscle tissue in the
wall of the right atrium.
• Impulses from the pacemaker spread quickly
through the walls of both atria, prompting the atria
to contract at the same time.
• The AV (atrioventricular) node
– is a relay point that delays the signal and
– sends impulses to the ventricles.
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Figure 23.6
Pacemaker
(SA node)
AV node
Right atrium
Right ventricle
1 Pacemaker generates
2 Impulses spread
electrical impulses.
through atria.
3 Impulses reach
(a) The heart’s natural pacemaker
Wire leading Heart
to SA node
(b) Artificial pacemaker
Artificial
pacemaker
ventricles.
The Pacemaker and the Control of Heart Rate
• The impulses sent by the pacemaker can be
– detected by electrodes placed on the skin and
– recorded as an electrocardiogram (ECG or
EKG).
• In certain kinds of heart disease, the heart fails to
maintain a normal rhythm.
• The remedy for this failure of the electrical control
of the heart is an artificial pacemaker, a small
electronic device surgically implanted near the SA
node.
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Blood Vessels
• If the heart is the body’s “pump,” then the
“plumbing” is the system of arteries, veins, and
capillaries.
– Arteries carry blood away from the heart.
– Veins carry blood toward the heart.
– Capillaries allow for exchange between the
bloodstream and tissue cells.
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Blood Vessels
• All blood vessels are lined by a thin layer of tightly
packed epithelial cells.
• Structural differences in the walls of the different
kinds of blood vessels correlate with their different
functions.
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Figure 23.7
From heart
To heart
Epithelium
Valve
Epithelium
Epithelium
Smooth
muscle
Smooth
muscle
Connective
tissue
Connective
tissue
Artery
Venule
Arteriole
Capillary
Vein
Blood Flow through Arteries
• The force that blood exerts against the walls of
blood vessels is blood pressure.
– Blood pressure pushes blood from the heart to the
capillary beds.
– A pulse is the rhythmic stretching of the arteries
caused by the pressure of blood forced into the
arteries during systole.
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Blood Flow through Arteries
• Optimal blood pressure for adults is
– below 120 systolic and
– below 80 diastolic.
• High blood pressure, or hypertension, is
persistent
– systolic blood pressure higher than 140 and/or
– diastolic blood pressure higher than 90.
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Blood Flow through Capillary Beds
• At any given time, only about 5–10% of the
capillaries have a steady flow of blood, with the
exception of the brain
• Blood flow through capillaries may be diverted
from one part of the body to another, depending
on need.
• This is called shunting
• There are three main locations which demand
blood: the brain, muscles, digestion
• In general, the body does one of these at a time
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Blood Flow through Capillary Beds
• The walls of capillaries are thin and leaky.
– At the arterial end of the capillary, blood pressure
pushes fluid rich in oxygen, nutrients, and other
substances into the interstitial fluid.
– At the venous end of the capillary, CO2 and other
wastes diffuse from tissue cells into the interstitial
fluid, and then into the capillary bloodstream.
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Figure 23.8
Tissue cell
Capillary
Red blood cell
Diffusion
of O2 and
nutrients out
of capillary
and into
tissue cells
Diffusion
of CO2 and
wastes out
of tissue
cells and
into capillary
To vein
LM
Interstitial fluid
(a) Capillaries
(b) Chemical exchange
Figure 23.8a
Capillary
LM
Red blood cell
(a) Capillaries
Figure 23.8b
Tissue cell
Diffusion
of O2 and
nutrients out
of capillary
and into
tissue cells
Diffusion
of CO2 and
wastes out
of tissue
cells and
into capillary
To vein
Interstitial fluid
(b) Chemical exchange
Blood Return through Veins
• Blood returns to the heart
– after chemicals are exchanged between the blood
and body cells and
– at a pressure that has nearly dropped to zero.
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Blood Return through Veins
• Blood moves back toward the heart because of
– surrounding skeletal muscles that compress the
veins and
– one-way valves that permit blood flow only toward
the heart.
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Figure 23.9
To heart
Valve (open)
Skeletal muscle
Valve (closed)
Blood: know all of this
• An adult human has about 5 L (11 pints) of blood.
• By volume, blood is
– a little less than half cells and
– a little more than half plasma, consisting of about
– 90% water and
– 10% dissolved salts, proteins, and other
molecules.
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Figure 23.10
Plasma
(55%)
Water (90%
of plasma)
Cellular
elements (45%)
Red blood cells
(erythrocytes)
Proteins
Dissolved salts
(such as sodium,
potassium, calcium)
Substances being
transported (such
as O2, CO2, nutrients,
wastes, hormones)
White blood cells
(leukocytes)
Blood
Platelets
Figure 23.10a
Plasma
(55%)
Cellular
elements (45%)
Water (90%
of plasma)
Red blood cells
(erythrocytes)
Proteins
Dissolved salts
White blood cells
(such as sodium,
(leukocytes)
potassium, calcium)
Substances being
transported (such
as O2, CO2, nutrients,
wastes, hormones)
Platelets
Blood
• Suspended in plasma are three types of cellular
elements:
1. red blood cells,
2. white blood cells, and
3. platelets.
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Red Blood Cells and Oxygen Transport
• Red blood cells (erythrocytes)
– are the most numerous type of blood cell and
– are shaped like discs with indentations in the
middle.
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Figure 23.12
CELLULAR COMPONENTS OF BLOOD
White Blood Cells
(cells that fight infection)
Colorized SEM
Platelets
(bits of membrane-enclosed
cytoplasm that aid clotting)
Colorized SEM
Red Blood Cells
(cells that carry oxygen)
Colorized SEM
Colorized SEM
Colorized SEM
Fibrin
Red blood cell
Blood Typing
• Carbohydrate-containing molecules on the surface
of red blood cells determine the blood type.
These are called surface antigens
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Figure 9.20
Blood Typing
Blood
Group
(Phenotype) Genotypes
Red Blood Cells
Carbohydrate
A
Antibodies
Present in
Blood
A
IAIA
or
IAi
B
IBIB
or
IBi
AB
IAIB
—
O
ii
Anti-A
Anti-B
Carbohydrate
B
Anti-B
Anti-A
Reactions When Blood from Groups Below
Is Mixed with Antibodies from Groups at Left
A
O
B
AB
Figure 9.20c
Red Blood Cells and Oxygen Transport
• Each red blood cell contains approximately 250
million molecules of hemoglobin, which
– contains iron and
– transports oxygen throughout the body.
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Red Blood Cells and Oxygen Transport
• Anemia may result from
– an abnormally low amount of hemoglobin or
– a low number of red blood cells.
• The hormone erythropoietin (EPO) boosts
production of red blood cells.
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White Blood Cells and Defense
• White blood cells (leukocytes)
– fight infections,
– are larger than red blood cells,
– lack hemoglobin, and
– are much less abundant than red blood cells
(about 700 times fewer).
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Figure 23.12b
Colorized SEM
White Blood Cells
(cells that fight infection)
Platelets and Blood Clotting
• Blood contains two components that aid in
clotting:
1. platelets, bits of cytoplasm pinched off from
larger cells in the bone marrow, and
2. clotting factors released from platelets that
convert fibrinogen, a protein found in
plasma, into a threadlike protein called fibrin.
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Figure 23.12c
Colorized SEM
Platelets
(bits of membrane-enclosed
cytoplasm that aid clotting)
Colorized SEM
Fibrin
Red blood cell
Platelets and Blood Clotting
• In the inherited disease hemophilia, excessive and
sometimes fatal bleeding can occur from even
minor cuts and bruises.
• Hemophilia is caused by a genetic mutation in one
of several genes that code for clotting factors.
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Stem Cells and the Treatment of Leukemia
• Leukemia
– is cancer of white blood cells and
– may require treatment using
– radiation,
– chemotherapy, and/or
– bone marrow transplantation.
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Cardiovascular Disease
• The cardiovascular system contributes to
homeostasis by
– exchanging nutrients and wastes with the
interstitial fluid,
– controlling the composition of blood by moving it
through the lungs, liver, and kidneys,
– helping to regulate temperature by moving blood
to or away from the skin,
– distributing hormones, and
– defending against foreign invaders.
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Cardiovascular Disease
• Cardiovascular disease
– includes all diseases affecting the heart and blood
vessels,
– accounts for 40% of all deaths in the United
States, and
– kills more than 1 million people each year.
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Cardiovascular Disease
• Coronary arteries
– supply the heart muscle and
– can narrow or close, contributing to a heart attack.
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Figure 23.13
Aorta
Coronary artery
(supplies oxygen
to the heart muscle)
Dead muscle
tissue
Blockage
Cardiovascular Disease
• Atherosclerosis
– is a chronic cardiovascular disease and
– results from fatty deposits called plaque that
develop in the inner walls of arteries, clogging the
passages through which blood can flow.
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Figure 23.14
Passageway
for blood
Connective
tissue
Smooth
tissue
Partially blocked
passageway
Plaque
Epithelium
Normal artery
Artery partially blocked by plaque
Cardiovascular Disease
• Cardiovascular disease
– involves inherited factors but
– can be reduced by
– not smoking,
– exercising regularly, and
– eating a heart-healthy diet.
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UNIFYING CONCEPTS OF ANIMAL RESPIRATION
• Cells using cellular respiration
– need a steady supply of oxygen and
– must continuously dispose of CO2.
• The respiratory system promotes this gas
exchange.
Figure 23.UN01
CO2
O2
Environment
Cell
C6H12O6
Glucose
6 O2
Oxygen
Cellular
respiration
6 CO2
6 H2O
ATP
Carbon
dioxide
Water
Energy
The Structure and Function of Respiratory Surfaces
• Animals can get oxygen from
– the atmosphere, which contains about 21%
oxygen, and
– bodies of water, which contain about 3–5%
oxygen.
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The Structure and Function of Respiratory Surfaces
• Gas exchange occurs at the respiratory surface,
which must be
– large enough to take up oxygen for every cell in
the body and
– adapted to the lifestyle of the organism.
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The Structure and Function of Respiratory Surfaces
• Moist skin is used as a respiratory surface in
earthworms.
• In aquatic environments, the main respiratory
surfaces are
– skin and
– extensions of the body surface called gills.
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Figure 23.15
Cross section of
respiratory surface (the
skin covering the body)
Body surface
Respiratory
surface (gill)
CO2
CO2
O2
(a) Skin
Capillaries
Capillaries
O2
(b) Gills
The Structure and Function of Respiratory Surfaces
• In most land-dwelling animals, the respiratory
surfaces are
– folded into the body and
– open to the air only through narrow tubes.
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The Structure and Function of Respiratory Surfaces
• Insects breathe using a tracheal system, an
extensive network of internal tubes called
tracheae that
– branch throughout the body and
– extend to nearly every cell.
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Figure 23.16
Body
surface
Body
surface
Respiratory
surface
(tracheae)
O2
CO2
(a) Tracheae
Body cells
(no capillaries)
Respiratory
surface
(within lung)
CO2 O2
CO2
(b) Lungs
O2
Capillary
The Structure and Function of Respiratory Surfaces
• Lungs
– are located in only one part of the body and
– are the most common respiratory surface of
snails, some spiders, and terrestrial vertebrates.
• The circulatory system transports gases between
the respiratory surface and the rest of the body.
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Figure 23.17
RESPIRATORY ORGANS
Skin
(entire body
surface)
Gills
(extensions of the
body surface)
Tracheae
(branching
internal tubes)
Lungs
(localized
internal organs)
Gills
Tracheae
(internal
tubes)
Moist skin of a leech Gills of a sea slug
Tracheae of a silk
moth caterpillar
Model of a pair of
human lungs
THE HUMAN RESPIRATORY SYSTEM
• The human respiratory system has three phases
of gas exchange:
1. breathing, the ventilation of the lungs by alternate
inhalation and exhalation,
2. transport of oxygen from the lungs to the rest of
the body via the circulatory system, and
3. diffusion of oxygen from the blood and release of
CO2 into the blood by cells of the body.
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Figure 23.18-3
O2 1 Breathing
CO2
Lung
2 Transport of gases by
the circulatory system
Circulatory system
3 Exchange of gases
with body cells
Mitochondria
O2
CO2
Capillary
Cell
The Structure and Function of the Human
Respiratory System
• Air moves sequentially from the mouth and
nose to
– the pharynx, where digestive and respiratory
systems meet,
– the larynx (voice box) and trachea (windpipe),
– the bronchi (one bronchus to each lung),
– the bronchioles, the smallest branches of the
tubes within the lungs, and
– the alveoli, the air sacs where gas exchange
primarily occurs.
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Figure 23.19
Pharynx
Nasal cavity
Esophagus
Larynx (voice box)
Left lung
Trachea (windpipe)
Right lung
Bronchus
To
heart
O2-rich
blood
From
heart
O2-poor
blood
Bronchiole
Bronchiole
O2
Diaphragm
Heart
(a) Overview of the human respiratory system
CO2
Alveoli
Blood
capillaries
(b) The structure of alveoli
The Structure and Function of the Human
Respiratory System
• Muscles in the voice box can stretch vocal cords
within the larynx.
• During exhalation, outgoing air can produce vocal
sounds as air passes by the stretched vocal cords.
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Taking a Breath
• Breathing is the alternating process of
– inhalation and
– exhalation.
• During inhalation, the chest is expanded by the
– upward movement of the ribs and
– downward movement of the diaphragm.
• Air moves into the lungs by negative pressure
breathing, as the air pressure in the lungs is
lowered by the expansion of the chest.
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Figure 23.20
Rib cage
expands as
rib muscles
contract
Air
inhaled
Rib cage gets
smaller as
rib muscles
relax
Air
exhaled
Lung
Diaphragm
contracts
(moves
down)
Inhalation
(Air pressure is higher in
atmosphere than in lungs.)
Diaphragm
relaxes
(moves up)
Exhalation
(Air pressure is lower in
atmosphere than in lungs.)
Taking a Breath
• Breathing can be controlled
– consciously, as you deliberately take a breath, or
– unconsciously.
• Breathing control centers in the brain stem
– automatically control breathing most of the time
and
– regulate breathing rate in response to CO2 levels in
the blood.
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Figure 23.21-3
Brain
1
Breathing
control
centers
CO2 levels in the
blood rise as a
result of exercise.
2 Breathing control
centers in the brain
monitor the rising CO2
levels in the blood.
3
Rib muscles
Diaphragm
Nerve signals
trigger contraction
of muscles to
increase breathing
rate and depth.
The Role of Hemoglobin in Gas Transport
• The human respiratory system
– takes in O2,
– expels CO2, but
– relies on the circulatory system to shuttle these
gases between the lungs and the body’s cells.
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Figure 23.22
O2 in
inhaled air
CO2 in
exhaled air
Air spaces
Alveolus
CO2
O2
Capillaries
of lung
O2-rich,
CO2-poor
blood
CO2-rich,
O2-poor
blood
Heart
Tissue
capillaries
CO2
Interstitial
fluid
O2
Tissue cells throughout body
The Role of Hemoglobin in Gas Transport
• However, there is one problem with this simple
gas delivery system.
– Problem: Oxygen does not readily dissolve in
blood plasma.
– Solution: Oxygen is carried in hemoglobin
molecules within red blood cells.
• A shortage of iron
– causes a decrease in the rate of hemoglobin
synthesis and
– can lead to anemia.
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Figure 23.23
Heme
group
Iron
atom
O2 loaded
in lungs
O2 unloaded
in tissues
Polypeptide chain
O2
O2
How Smoking Affects the Lungs
• Breathing exposes your respiratory tissues to
potentially damaging chemicals, including one of
the worst pollutants, tobacco smoke.
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How Smoking Affects the Lungs
• Smoking
– kills half of all people who smoke, about 440,000 Americans
every year,
– causes 90% of all lung cancer (one of the deadliest forms of
cancer), and
• Tobacco smoke
– damages the cells that line the bronchi and trachea and
– interferes with the normal cleansing mechanism of the
respiratory system, allowing more toxin-laden smoke particles
to reach and damage the lungs’ delicate alveoli.
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