Download Chapter 33 Circulation

Biology
Concepts and Applications | 9e
Starr | Evers | Starr
Chapter 33
Circulation
© Cengage Learning 2015
© Cengage Learning 2015
33.1 How Do Animals Move Materials To
and From Body Cells?
• The circulatory system supplies animal
cells with nutrients and oxygen
– Also rids cells of waste products
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Open and Closed Circulatory Systems
• Circulatory system: organ system that
speeds the distribution of materials within
an animal’s body
– Typically includes one or more hearts
(muscular pumps) that propel a circulatory
fluid through vessels
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Open and Closed Circulatory Systems
(cont’d.)
• Open circulatory system: heart pumps
circulatory fluid (hemolymph) into openended vessels
– Hemolymph leaves the vessels and mixes
with the interstitial fluid
– Hemolymph makes direct exchanges with
cells and is drawn back into the heart through
open holes
– Arthropods and most mollusks have an open
system
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ANIMATION: Types of circulatory systems
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Open and Closed Circulatory Systems
(cont’d.)
• Closed circulatory system: heart pumps
blood through continuous vessel system
– Artery: large-diameter vessel that carries
blood away from the heart
– Capillary: small-diameter blood vessel;
exchanges substances with interstitial fluid
– Vein: large-diameter vessel that returns blood
to the heart
– All vertebrates and some invertebrates have a
closed system
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Evolution of Vertebrate Circulatory
Systems
• Most fishes: two-chambered heart
• Amphibians and most reptiles: threechambered heart
• Mammals and birds: four-chambered heart
– Evolved through morphological convergence
– Enhanced blood flow provided by a fourchambered heart supports high metabolic
activity
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ANIMATION: Circulatory systems
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Evolution of Vertebrate Circulatory
Systems (cont’d.)
• Pulmonary circuit: blood flows from the
heart to the lungs and then back to the
heart
• Systemic circuit: blood flows from the
heart to body tissues and then back to the
heart
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33.2 What Is the Route of Blood Flow in a
Human Body?
• Components of the pulmonary circuit:
– Pulmonary artery: carries blood from the heart
to a lung
– Pulmonary vein: carries blood from a lung to
the heart
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ANIMATION: Human blood circulation
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33.2 What Is the Route of Blood Flow in a
Human Body?
• Components of the systemic circuit:
– Aorta: large artery; receives oxygenated blood
pumped out of the heart’s left ventricle
– Superior vena cava: vein that delivers blood
from the upper body to the heart
– Inferior vena cava: vein that delivers blood
from the lower body to the heart
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33.3 How Does the Human Heart
Function?
• Atrium: heart chamber that receives blood
from veins
• Ventricle: heart chamber that pumps blood
into arteries
• Atrioventricular (AV) valve: located
between the two chambers; functions like
a one-way door to control blood flow
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How Does the Human Heart Function?
(cont’d.)
right lung
left lung
pericardium
diaphragm
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How Does the Human Heart Function? (cont’d.)
superior vena cava
(flow from head, arms)
aorta (to body)
trunk of pulmonary
arteries (to lungs)
pulmonary valve
(closed)
right pulmonary
veins (from lungs)
aortic valve (closed)
left pulmonary
veins (from lungs)
Left Atrium
Right Atrium
right AV valve
(open)
left AV valve
(open)
Right Ventricle
Left Ventricle
inferior vena cava
(from trunk, legs)
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cardiac muscle
septum
How Does the Human Heart Function?
(cont’d.)
• Oxygen-poor blood is delivered to the right
atrium by the superior and inferior venae
cavae
• Blood flows through the right AV valve into
the right ventricle
• Right ventricle pumps blood through the
pulmonary valve into the pulmonary
arteries, and through the pulmonary circuit
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How Does the Human Heart Function?
(cont’d.)
• Oxygenated blood returns to the left atrium
via pulmonary veins
• Blood flows through the left AV valve into
the left ventricle
• Left ventricle pumps the blood through the
aortic valve into the aorta and then to the
body’s tissues
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The Cardiac Cycle
• Cardiac cycle: sequence of contraction
and relaxation of heart chambers that
occurs with each heartbeat
– Diastole: relaxation phase of the cardiac cycle
– Systole: contractile phase of the cardiac cycle
• During the cardiac cycle a “lub-dup” sound
is produced
– “Lub”: AV valves are closing
– “Dup”: pulmonary valves are closing
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ANIMATION: Cardiac cycle
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Setting the Pace
• Gap junctions allow action potentials to
spread between cardiac muscle cells
– Sinoatrial (SA) node: cardiac pacemaker;
group of cells that spontaneously emits
rhythmic action potentials that result in
contraction of cardiac muscle
– Atrioventricular (AV) node: clump of cells that
conveys excitatory signals between the atria
and ventricles
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Setting the Pace (cont’d.)
SA node
(cardiac
pacemaker)
AV node
conducting
fibers
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33.4 What Are the Functions and
Components of Blood?
• Functions of blood:
– Carries oxygen and nutrients to cells
– Carries metabolic wastes to organs for
disposal
– Facilitates communication by distributing
hormones
– Transports cells and proteins that protect and
repair tissues
– Maintains a stable internal temperature
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3D ANIMATION: The Blood
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Plasma
• Plasma: fluid portion of blood
– Mostly water with plasma proteins
– Function of albumins and other plasma
proteins:
• Draws water into capillaries
• Transport of steroid hormones, vitamins, and lipids
• Blood clotting
• Immunity
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Cellular Components
• Red blood cell (erythrocyte): hemoglobinfilled blood cell that carries oxygen
• White blood cell (lymphocyte): blood cell
with a role in housekeeping and defense
• Platelet: cell fragment that helps blood clot
– Fibrin: threadlike protein formed during blood
clotting from the soluble plasma protein
fibrinogen
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ANIMATION: Hemostasis
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33.5 How Does Blood Travel to Tissues?
• Blood pumped out of ventricles enters
arteries
• The elastic properties of an artery help
keep blood flowing, even when the
ventricles relax
• The bulging of an artery with each
ventricular contraction is the pulse
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ANIMATION: Vessels
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Adjusting Flow at Arterioles
• The body adjusts blood flow via the
arterioles: blood vessels that convey blood
from an artery to capillaries
– Vasodilation: widening of a blood vessel;
smooth muscle relaxes
– Vasoconstriction: narrowing of a blood vessel;
smooth muscle contracts
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33.6 What Is Blood Pressure?
• Blood pressure: pressure exerted by blood
against the wall of a vessel
– Systolic pressure: highest pressure of a
cardiac cycle; occurs as contracting ventricles
force blood into the arteries
– Diastolic pressure: lowest blood pressure of a
cardiac cycle; occurs when ventricles are
relaxed
– Normal blood pressure is about 120/80 mm
Hg
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What Is Blood Pressure? (cont’d.)
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33.7 How Does Blood Exchange
Substances With Body Cells?
• As blood flows through a circuit, it moves
fastest through arteries, slower in
arterioles, and slowest in capillaries
– Slowdown in capillaries occurs because the
body has tens of billions of capillaries
– Collective cross-sectional area is far greater
than that of the arterioles
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33.7 How Does Blood Exchange
Substances With Body Cells?
• Materials move between capillaries:
– Plasma fluid is forced out through spaces
– Oxygen diffuses into interstitial fluid; nutrients
are transported into interstitial fluid
– Carbon dioxide (CO2) diffuses into capillaries;
wastes are transported into capillaries
– Water moves by osmosis from the interstitial
fluid into the plasma near venous end
– Fluid is returned by the lymphatic system
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ANIMATION: Lymph vascular system
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33.8 How Does Blood Return to the Heart?
• Blood from capillaries flows into a venule:
thin-walled vessel that carries blood to
vein
• Blood at low pressure moves through
veins and back toward the heart:
– One-way valves prevent backflow
– Smooth muscle facilitates blood flow
– Skeletal muscles used in limb movements
help blood move through veins
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How Does Blood Return to the Heart?
(cont’d.)
valve
open
valve
closed
valve
closed
valve
closed
A
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B
33.9 What Causes Common Heart
Problems?
• The leading cause of death in the United
States is cardiovascular disease
– Kills about one million people every year
• Risk factors:
– Smoking, family history, hypertension, high
cholesterol, diabetes mellitus, and obesity
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What Causes Common Heart Problems?
(cont’d.)
• Arrhythmias: abnormal heart rhythms
– Examples: bradycardia, tachycardia, atrial
fibrillation, and ventricular fibrillation
• Atherosclerosis: buildup of lipids in the
arterial wall causes narrowing of the blood
vessel
– Increased LDL levels are a risk factor
– A heart attack occurs when a coronary artery
is completely blocked
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What Causes Common Heart Problems?
(cont’d.)
plaque
clot
A Normal artery.
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B Artery narrowed by an atherosclerotic
plaque. A clot has adhered to
the plaque, further narrowing the artery.
What Causes Common Heart Problems?
(cont’d.)
one
coronary
artery
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What Causes Common Heart Problems?
(cont’d.)
vein from leg
used to bypass
blockage
blocked
coronary artery
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What Causes Common Heart Problems?
(cont’d.)
plaque flattened by
balloon angioplasty
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stent (metal mesh) placed
to keep artery open
33.10 What Are the Functions of the
Lymphatic System?
• Lymph vascular system: system of vessels
that takes up interstitial fluid and carries it
(as lymph) to the blood
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3D ANIMATION: The Lymphatic System
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Lymphoid Organs and Tissues
• Lymph nodes: small mass of lymphatic
tissue through which lymph filters
– Contains many lymphocytes (B and T cells)
• Spleen: large lymphoid organ
– Functions in immunity; filters pathogens, old
red blood cells, and platelets from the blood
• Thymus: site of T lymphocyte
differentiation
© Cengage Learning 2015