Transcript Blood Vessels

BIOLOGY
A GUIDE TO THE NATURAL WORLD
FOURTH EDITION
DAVID KROGH
Transport and Exchange 1:
Blood and Breath
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29.1 The Cardiovascular System
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The Cardiovascular System
• The human cardiovascular system is a fluid
transport system that consists of the heart, all
the body’s blood vessels, the blood, and the
bone marrow tissue in which red blood cells are
formed.
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The Cardiovascular System
• This system transports substances both to and
from the body’s cells.
• Such substances include oxygen, carbon
dioxide, nutrients, vitamins, hormones, waste
products, and immune system cells and
proteins.
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Transport and Exchange System
Respiratory system
moves O2 into, and
CO2 out of the body.
Cardiovascular system
transports materials to and
from all other systems.
Digestive system
transforms food into a form
that can be transported
throughout the body.
Urinary system
filters bodily fluids, removes
waste while conserving
water and other materials.
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Figure 29.1
29.2 The Composition of Blood
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The Composition of Blood
• Blood has two primary components: formed
elements and blood plasma.
• Formed elements are blood cells and cell
fragments.
• Blood plasma is the fluid portion of blood in
which the formed elements are suspended.
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The Composition of Blood
• There are three kinds of formed elements:
– red blood cells
– white blood cells
– platelets
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The Composition of Blood
blood sample
55%
plasma
formed
elements
45%
Plasma
Formed elements
Red blood cells 99.9%
White blood cells
0.1%
Platelets
Red blood cells
Water
92%
Plasma proteins 7%
Other solutes
1%
White blood cells
Platelets
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Figure 29.2
The Composition of Blood
• Red blood cells carry oxygen to, and carbon
dioxide from, every part of the body.
• White blood cells are central to the immune
system.
• Platelets are small fragments of cells that are
important in the blood-clotting process.
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Transport Cells
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Figure 29.3
Plasma
• Blood plasma is 92 percent water, but it also
contains other materials, including proteins.
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Plasma
• There are three primary classes of plasma
proteins:
– Albumins, which transport hormones and fatty
acids.
– Fibrinogen, which aids in blood clotting.
– Globulins, which aid the immune system and serve
as transport proteins.
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Transport Proteins
• Two transport proteins are important in the
health of the heart.
• Low-density lipoproteins (LDLs) carry lipids to
bodily tissues from the liver and small
intestines.
• High-density lipoproteins (HDLs) carry lipids
from these tissues to the liver.
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Plasma
• Other plasma compounds include nutrients,
wastes, hormones, and electrolytes.
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29.3 Blood Vessels
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Blood Vessels
• Blood vessels carrying blood away from the
heart are arteries; blood vessels returning blood
to the heart are veins.
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Blood Vessels
• The smallest blood vessels, the capillaries,
connect the arteries with the veins.
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Blood Vessels
connective
tissue
connective
tissue
muscle
epithelium
muscle
vein
epithelium
artery
capillary
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Figure 29.4
Blood Vessels
• Arteries and veins are always made of three
distinct layers of tissue.
• The middle layer is muscle that allows arteries
and veins to widen or constrict in diameter.
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Blood Vessels
• Capillaries, conversely, are composed of only a
single layer of cells.
• This allows the movement of blood-borne
materials into and out of them along their
length.
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29.4 The Heart and Blood Circulation
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The Heart and Blood Circulation
• The heart’s contractions propel blood out to the
various tissues of the body.
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The Heart and Blood Circulation
• Two blood circulation loops exist in the body.
• The first loop is the pulmonary circulation, in
which blood circulates between the heart and
the lungs (with the result that blood is
oxygenated).
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The Heart and Blood Circulation
• The second loop is the systemic circulation, in
which blood circulates between the heart and
the rest of the body.
• The result is that needed materials are
transported to and from all parts of the body.
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The Heart and Blood Circulation
The pulmonary and systemic circulation networks
The circulation of blood through the heart
superior
vena cava
The right side of
the heart pumps
deoxygenated
blood to the lungs.
The left side of the
heart pumps
oxygenated blood to
the entire body.
pulmonary
arteries
pulmonary
circulation
(to lungs)
pulmonary
veins
systemic
veins
Blood is delivered
to the lungs via the
pulmonary arteries.
Deoxygenated
blood enters the
right atrium
through the superior
and inferior vena
cavae.
Oxygenated blood
returns from the
lungs through the
pulmonary veins.
Blood then
moves into the
left atrium which
pumps it into the
left ventricle.
Powerful contractions
of the
left ventricle force
blood into the aorta.
systemic
arteries
systemic
circulation
(to all tissues)
From the
aorta, blood is
distributed to the
rest of the body.
inferior
vena cava
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The right atrium pumps
blood into the
right ventricle, which
contracts, pumping
blood to the lungs.
Figure 29.5
The Heart and Blood Circulation
• The human heart contains four muscular
chambers:
– Two for pulmonary circulation (the right atrium and
right ventricle).
– Two for systemic circulation (the left atrium and
left ventricle).
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The Heart and Blood Circulation
• A series of valves that open and close ensures
that blood flows only one way through the
heart.
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The Cardiovascular System
PLAY
Animation 29.1: The Cardiovascular System
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29.5 What is a Heart Attack?
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Heart Attacks
• About half of all deaths in the United States
today are caused by the blockage of one or
more of the coronary arteries that supply heart
tissue with blood.
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Heart Attacks
• Such blockages generally are caused by a
buildup of low-density lipoprotein (LDL)
molecules in a coronary artery, followed by an
immune system reaction to these LDLs and
formation of a blood clot in the artery.
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Heart Attacks
• A heart attack occurs when this process results
in the complete blockage of a coronary artery,
which cuts off the blood supply to groups of
cells within the heart, thus killing them.
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Critical Vessels
aorta
superior
vena cava
pulmonary
artery
right
coronary
artery
left main
coronary
artery
site of
blockage
left anterior
descending
coronary
artery
blood clot
core of
oxidized
LDL
molecules
damaged
heart muscle
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Figure 29.6
29.6 Distributing the Goods:
The Capillary Beds
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The Capillary Beds
• Arteries near the heart branch into smaller
arterioles, which feed into the delivery vehicles
of the cardiovascular system, the capillary beds.
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Capillary Beds
• The capillary beds then feed back into the
body’s system of veins that returns blood to the
heart.
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Capillary Beds
artery
vein
capillary bed
arteriole
venule
interstitial fluid
O2 glucose
epithelial cells of
capillary wall
CO2 wastes
tissue
cells
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Figure 29.7
Capillary Beds
• Materials needed by the body’s tissues move
out of the capillaries and into the interstitial
fluid that surrounds both the capillaries and
nearby cells.
• Meanwhile, carbon dioxide and wastes from
these cells flow into capillaries from the
interstitial fluid.
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Capillary Beds
• The movement of all these substances is aided
by their concentration gradients.
• They move from areas of their higher
concentration to areas of their lower
concentration.
• The movement of water is driven in two
directions by two opposing forces.
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Capillary Beds
• At the arterial end of the capillary beds, blood
pressure tends to drive water out of the
capillaries.
• But at the venous end of the beds, osmosis
overcomes the force of blood pressure and pulls
most of this water back into the capillaries.
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Capillary Beds
• Blood pressure is at low levels by the time
blood has moved through the capillaries.
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Capillary Beds
• Blood returns to the heart through the
contraction of skeletal muscles, which squeeze
the veins in a way that moves the venous blood
toward the heart.
• A system of valves in the veins ensures that this
movement is one way—toward the heart.
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One-Way Flow to the Heart
Valves allow blood
to go forward . . .
valve
open
. . . but not
backward
valve
closed
muscles
contracted
muscles
relaxed
valve
closed
valve
open
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Figure 29.8
29.7 The Respiratory System
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The Respiratory System
• The central function of the respiratory system is
to capture oxygen and to dispose of carbon
dioxide.
• It also aids in controlling pH balance in the
bloodstream and in producing sounds for
speaking.
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The Respiratory System
• Respiration can be defined as the exchange of
gases between the atmosphere outside the body
and the cells within it.
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The Respiratory System
• The respiratory system includes:
–
–
–
–
–
the lungs, the nose, nasal cavity, and sinuses
the pharynx (upper throat)
the larynx (voice box)
the trachea (windpipe)
the conducting passageways, called bronchi and
bronchioles, that lead to the lungs
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The Respiratory System
• The lungs themselves are largely composed of
the tiny hollow sacs, called alveoli.
• Alveoli lie at the end of each bronchiole and
they are the air exchange chambers of the body.
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The Respiratory System
Anatomy of the lungs
The structure of alveoli
sinuses
vein
nasal cavity
artery
larynx
alveolus
trachea
pharynx
left lung
esophagus
left bronchus
right lung
bronchioles
capillary network
A bronchiole and its alveoli
diaphragm
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Figure 29.9
The Respiratory System
• The enormous surface area of the alveoli and
their associated capillaries is used for the
exchange of oxygen and carbon dioxide.
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29.8 Steps in Respiration
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Steps in Respiration
• The first step in respiration is breathing or
ventilation, meaning the physical movement of
air into and out of the lungs.
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Ventilation
respiratory
cycle
inhalation
Elevation of rib cage
and contraction of
diaphragm decrease
pressure in the lungs,
causing air to flow in.
exhalation
ribs
lungs
Depression of rib
cage and elevation
of diaphragm
increase pressure
in lungs causing
air to flow out.
diaphragm
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Figure 29.10
Steps in Respiration
• Once in the lungs, oxygen diffuses across the
thin wall of an alveolus into an adjacent
capillary and binds with hemoglobin protein in
red blood cells.
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Steps in Respiration
• Oxygen then moves with the blood cells to the
heart.
• The heart pumps the blood to body tissues,
where the oxygen diffuses into the interstitial
fluid and then into nearby cells.
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Steps in Respiration
• The carbon dioxide produced in the body’s cells
moves into nearby capillaries, to be carried to
the lungs.
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Gas Exchange in the Body
air in
air out
alveolus in
lung
O2
CO2
capillary
CO2
O2
tissue cell
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Figure 29.11
Steps in Respiration
• All the oxygen loaded into red blood cells binds
initially with the hemoglobin in them.
• Carbon dioxide is transported both within red
blood cells and in blood plasma.
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The Respiratory System
PLAY
Animation 29.2: The Respiratory System
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