Transcript Chapter 23: Circulation

BIOLOGY
CONCEPTS & CONNECTIONS
Fourth Edition
Neil A. Campbell • Jane B. Reece • Lawrence G. Mitchell • Martha R. Taylor
CHAPTER 23
Circulation
Modules 23.1 – 23.3
From PowerPoint® Lectures for Biology: Concepts & Connections
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How Does Gravity Affect Blood Circulation?
• As with all land animals, the giraffe and the
corn snake are constantly subject to the force of
gravity
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• The circulatory system
keeps blood pumping
despite gravity’s pull
– Muscle contractions help
blood travel uphill in the
veins of a giraffe’s long
legs
– The wriggling of the corn
snake squeezes its veins
and increases circulation
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• Most animals have a circulatory system
– It transports O2 and nutrients to cells
– It takes away CO2 and other wastes
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23.1 The circulatory system associates intimately
with all body tissues
• Capillaries are microscopic blood vessels
– They form an intricate network among the tissue
cells
Capillary
Red
blood
cell
Figure 23.1A
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– No substance has to diffuse far to enter or leave
a cell
Capillary
INTERSTITIAL
FLUID
Diffusion of
molecules
Tissue
cell
Figure 23.1B
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MECHANISMS OF INTERNAL TRANSPORT
23.2 Several types of internal transport have
evolved in animals
• In cnidarians and
flatworms, the
gastrovascular cavity
functions in both
– digestion
– internal transport
Mouth
Circular
canal
Figure 23.2A
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• Most animals have a separate circulatory
system, either open or closed
• Open systems
– A heart pumps blood through open-ended
vessels into spaces between cells
Tubular heart
Pores
Figure 23.2B
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• Closed systems
– A heart pumps blood through arteries and
capillary beds
– The blood returns to the heart via veins
Capillary beds
Arteriole
Artery
(O2-rich blood)
Venule
Vein
Atrium
Gill
capillaries
Artery
Ventricle
(O2-poor blood)
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Heart
Figure 23.2C
23.3 Vertebrate cardiovascular systems reflect
evolution
Gill capillaries
• A fish has a single
circuit of blood flow
Heart:
Ventricle (V)
Atrium (A)
Systemic capillaries
Figure 23.3A
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• The cardiovascular system of land vertebrates
has two circuits
Lung capillaries
• The pulmonary circuit
– conveys blood between
the heart and gasexchange tissues
PULMONARY
CIRCUIT
A
• The systemic circuit
– carries blood between
the heart and the rest
of the body
A
V
Right
V
Left
SYSTEMIC
CIRCUIT
Systemic capillaries
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Figure 23.3B
THE MAMMALIAN CARDIOVACULAR SYSTEM
23.4 The human heart and cardiovascular system
typify those of mammals
• The mammalian heart has two thin-walled atria
that pump blood into the ventricles
– The thick-walled ventricles pump blood to all
other body organs
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Pulmonary
artery
Aorta
Superior
vena cava
Pulmonary
artery
LEFT
ATRIUM
RIGHT
ATRIUM
Pulmonary
veins
Pulmonary
veins
Semilunar
valve
Semilunar
valve
Atrioventricular
valve
Atrioventricular
valve
Inferior
vena cava
RIGHT
VENTRICLE
LEFT
VENTRICLE
Figure 23.4A
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7
Superior
vena cava
Capillaries of
Head and arms
Pulmonary
artery
Capillaries
of right lung
Pulmonary
artery
Aorta
9
Capillaries
of left lung
6
2
3
3
4
11
Pulmonary
vein
Pulmonary
vein
RIGHT ATRIUM
RIGHT VENTRICLE
5
1
LEFT ATRIUM
LEFT VENTRICLE
10
Aorta
Inferior
vena cava
Capillaries of
abdominal organs
and legs
8
Figure 23.4B
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23.5 The structure of blood vessels fits their
functions
• A single layer of epithelial cells forms capillary
walls
• Arteries and veins have smooth muscle and
connective tissue
– Valves in veins prevent the backflow of blood
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Epithelium
Valve
Basement
membrane
Epithelium
Epithelium
Smooth
muscle
CAPILLARY
Connective
tissue
Smooth
muscle
Connective
tissue
ARTERY
VEIN
VENULE
ARTERIOLE
Figure 23.5
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23.6 The heart contracts and relaxes rhythmically
• Diastole
– Blood flows from the
veins into the heart
chambers
1 Heart is
2 Atria
relaxed.
AV valves
are open.
contract.
• Systole
0.1 sec
– The atria briefly
contract and fill the
ventricles with blood
– Then the ventricles
contract and propel
blood out
0.3 sec
0.4 sec
SYSTOLE
3 Ventricles
contract.
Semilunar
valves
are open.
DIASTOLE
Figure 23.6
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• Heart valves prevent backflow
• Cardiac output
– The amount of blood pumped into the aorta by
the left ventricle per minute
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23.7 The pacemaker sets the tempo of the heartbeat
• The SA node (pacemaker) generates electrical
signals that trigger the contraction of the atria
• The AV node then relays these signals to the
ventricles
Pacemaker
(SA node)
Specialized
muscle fibers
AV node
Right
atrium
Right
ventricle
1
2
ECG
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3
4
Figure 23.7
• An electrocardiogram (ECG) is a recording of
electrical changes in the skin resulting from the
electrical signals in the heart
– Control centers in the brain adjust heart rate to
body needs
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23.8 Connection: What is a heart attack?
• A heart attack is damage that occurs when a
coronary feeding the heart is blocked
Aorta
Right
coronary
artery
Left
coronary
artery
Blockage
Dead muscle tissue
Figure 23.8A
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• Blood vessel blockage is usually due to blood
clots
Connective
tissue
Smooth
muscle
Epithelium
Plaque
Figure 23.8B
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23.9 Blood exerts pressure on vessel walls
• Blood pressure depends on
– cardiac output
– resistance of vessels
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• Pressure is
highest in the
arteries
– It drops to
zero by the
time the
blood
reaches the
veins
Systolic
pressure
Diastolic
pressure
Relative sizes and
numbers
of blood
vessels
Figure 23.9A
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• Three factors keep blood moving back to the
heart
– muscle contractions
– breathing
– one-way valves
Direction of
blood flow
in vein
Valve (closed)
Valve (open)
Skeletal muscle
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Figure 23.9B
23.10 Connection: Measuring blood pressure can
reveal cardiovascular problems
• Blood pressure is measured as systolic and
diastolic pressures
Blood pressure
120 systolic
80 diastolic
(to be
measured)
Pressure
in cuff
above
120
Rubber
cuff
inflated
with air
Artery
1
Pressure
in cuff
below
120
Sounds
audible in
stethoscope
Artery
closed
2
Pressure
in cuff
below 80
3
Sounds
stop
4
Figure 23.10
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• Hypertension is persistent systolic pressure
higher than 140 mm Hg and/or diastolic
pressure higher than 90 mm Hg
– It is a serious cardiovascular problem
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23.11 Smooth muscle controls the distribution of
blood
• Muscular constriction of arterioles and
precapillary sphincters controls the flow
through capillaries
Precapillary sphincters
Thoroughfare
channel
Arteriole
Thoroughfare
channel
Venule
Venule
Arteriole
Capillaries
1 Sphincters relaxed
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2 Sphincters contracted
Figure 23.11
23.12 Capillaries allow the transfer of substances
through their walls
Figure 23.12A
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• The transfer of materials between the blood and
interstitial fluid can occur by
– leakage through clefts in the capillary walls
– diffusion through the wall
– blood pressure
– osmotic pressure
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Tissue cells
Osmotic
pressure
Arterial
end of
capillary
Blood
pressure
INTERSTITIAL
FLUID
NET PRESSURE
OUT
Osmotic
pressure
Venous
end of
capillary
Blood
pressure
NET PRESSURE
IN
Figure 23.12B
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STRUCTURE AND FUNCTION OF BLOOD
23.13 Blood consists of cells suspended in plasma
• Plasma is an aqueous solution of various
substances
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Withdraw
blood
Centrifuge
Place in tube
PLASMA 55%
CONSTITUENT
MAJOR FUNCTIONS
Water
Solvent for
carrying other
substances
Salts
Sodium
Potassium
Calcium
Magnesium
Chloride
Bicarbonate
Osmotic balance,
pH buffering, and
regulation of
membrane
permeability
CELLULAR ELEMENTS 45%
CELL TYPE
NUMBER
Erythrocytes
(red blood cells)
5–6 million
Leukocytes
(white blood cells) 5,000–10,000
Plasma proteins
Albumin
Fibrinogen
Immunoglobins
(antibodies)
Osmotic balance,
pH buffering
Clotting
Immunity
Transport of
oxygen
(and carbon
dioxide)
Defense and
immunity
Lymphocyte
Basophil
Eosinophil
Substances transported by blood
Nutrients (e.g., glucose, fatty acids, vitamins)
Waste products of metabolism
Respiratory gases (O2 and CO2)
Hormones
FUNCTIONS
(per mm3 of blood)
Monocyte
Neutrophil
Platelets
250,000–
400,000
Blood clotting
Figure 23.13
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23.14 Red blood cells transport oxygen
• Red blood cells contain
hemoglobin
– Hemoglobin enables the
transport of O2
Figure 23.14
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23.15 White blood cells help defend the body
• White blood cells function both inside and
outside the circulatory system
– They fight infections and cancer
Basophil
Eosinophil
Monocyte
Neutrophil
Lymphocyte
Figure 23.15
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23.16 Blood clots plug leaks when blood vessels are
injured
• When a blood vessel
is damaged, platelets
respond
– They help trigger the
formation of an
insoluble fibrin clot
that plugs the leak
Figure 23.16B
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1 Injury to lining of blood
2 Platelet plug forms
3 Fibrin clot traps
vessel exposes connective
tissue; platelets adhere
blood cells
Connective
tissue
Platelet releases chemicals
that make nearby platelets sticky
Platelet
plug
Clotting factors from:
Platelets
Damaged cells
Calcium and
other factors
in blood plasma
Prothrombin
Thrombin
Fibrinogen
Fibrin
Figure 23.16A
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23.17 Connection: Stem cells offer a potential cure
for leukemia and other blood cell diseases
• All blood cells develop
from stem cells in bone
marrow
– Such cells may prove
valuable for treating
certain blood disorders
Figure 23.17
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