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Chapter Introduction
Transport Systems in Plants
7.1 Adaptations for Life on Land
7.2 Water Transport
7.3 Nutrient Transport
Transport Systems in Animals
7.4 Circulatory Systems
7.5 Circulation in Vertebrates
7.6 The Human Heart
7.7 Molecular Basis of Muscle Contraction
Regulation and Transport
7.8 Blood Pressure
7.9 Composition of Blood
7.10 The Circulatory System and Homeostasis
Chapter Highlights
Chapter Animations
Learning Outcomes
By the end of this chapter you will be able to:
A Summarize the adaptations made by plants to life
on land.
B Compare the structure and function of xylem and
phloem tissues.
C Describe the advantages offered by a closed
circulatory system.
D Explain what blood pressure is and describe
factors that affect it.
E Name the constituents of blood and describe the
function of each.
F Explain how the circulatory system functions in
homeostasis.
Transport Systems
 What system is responsible
for the movement of blood
throughout the body in
humans?
 How do transport systems
contribute to the survival of
multicellular organisms?
An arteriogram of a human hand showing
the arterial structure (enhanced).
Transport Systems
• Complex multicellular
organisms, such as most
land plants and animals,
cannot eliminate wastes by
diffusion and active transport
through their surfaces.
• Transport systems play a key
role in maintaining the
internal balance necessary
for life.
An arteriogram of a human hand showing
the arterial structure (enhanced).
Transport Systems in Plants
7.1 Adaptations for Life on Land
• The first land plants probably evolved from green
algae about 430 million years ago.
• Challenges posed by life out of water include:
– loss of moisture to the air
– soil contains water and minerals, but the
light and carbon dioxide needed for
photosynthesis must be obtained above
ground
Transport Systems in Plants
7.1 Adaptations for Life on Land (cont.)
• Two groups of plants emerged during this period:
– Vascular plants with specialized tissue, called
vascular tissue, that consists of cells joined into
tubes that transport water and nutrients
throughout the body of the plant
– Nonvascular plants in which complex transport
tissues did not evolve
• Vascular land plants differentiated into an
underground root system that absorbs water and
minerals and an aerial system of stems and leaves
that makes food.
Different parts of a plant
have different activities, all
of which require materials
that must be transported
where needed. Water is the
material needed in greatest
amounts. It also serves as
the transport fluid, carrying
minerals through one type
of transport tissue and the
products of photosynthesis
through another.
Transport Systems in Plants
7.1 Adaptations for Life on Land (cont.)
• Specialization in vascular plants required
additional adaptations:
– The sections of roots that absorb water generally lack a
cuticle and have increased surface area.
– Lignin, a hard material embedded in the cellulose
matrix of the cell walls, supports trees and other large
vascular plants.
– Hollow tube-shaped cells called xylem carry water and
minerals up from the roots.
– The phloem, which distributes organic nutrients throughout
the plant, consists of elongated cells arranged into tubes
filled with streaming cytoplasm.
The arrows identify the path of
water through this tree. Trace
the path of the water from the
root hairs through the xylem
tissues to the leaves.
Transport Systems in Plants
7.2 Water Transport
• The xylem of flowering plants
consists of two types of waterconducting cells, tracheids and
vessel elements, plus strong
weight-bearing fibers.
• Columns of vessel elements
form the xylem vessels
through which water moves
throughout the plant.
Transport Systems in Plants
7.2 Water Transport (cont.)
• Scientists have developed the cohesion-tension
hypothesis—based on the molecular properties of
water and transpiration—as the likely mechanism
for water transport through the xylem.
• The root system also exerts pressure that causes
water and other materials to ooze out of a cut
plant stem.
Transport Systems in Plants
7.2 Water Transport (cont.)
• Hydrogen bonds form between water molecules
causing cohesion—the tendency of water to
stick together.
• The positive and negative charges of water
molecules form weak bonds to other charged
molecules—the property called adhesion.
• Capillary action causes water to rise inside a tube
because the water molecules develop adhesion to
charged groups on the walls, pulling them upward;
additional water molecules are then drawn up by
cohesion.
Transport Systems in Plants
7.2 Water Transport (cont.)
• Due to cohesion, each water molecule that leaves
the plant during transpiration tugs on the one
behind it.
• The result is that a long chain of water molecules
is continually pulled through the xylem from root
to leaf.
Transport Systems in Plants
7.3 Nutrient Transport
• In vascular plants, nutrients
travel through living phloem
cells joined end to end.
• Tiny pores in the walls at the
ends of the phloem cells
allow the contents of the
cells to mix.
• Phloem channels are often
called sieve tubes.
Transport Systems in Plants
7.3 Nutrient Transport (cont.)
• Sugars and amino acids move through the phloem
cells from the leaves to other parts of the plant.
• The pressure-flow hypothesis is the best explanation
for the movement of sugars through the phloem.
• According to this hypothesis, water and dissolved
sugars move through the phloem from sources
(areas of higher pressure) to sinks (areas of
lower pressure).
Sources and sinks in phloem transport
Transport Systems in Animals
7.4 Circulatory Systems
• In unicellular and other
simple organisms,
substances pass across
the plasma membrane
between each cell and a
watery environment.
Numbers indicate the
pathway from endocytosis
of food to exocytosis of
indigestible wastes.
Transport Systems in Animals
7.4 Circulatory Systems (cont.)
• Most larger animals have digestive and excretory
organs and typically carry out transport with a
pump (heart) and other organs and tissues, such
as blood vessels and blood.
• Both the size of an organism and its level of activity
play a role in how complex and efficient this system
has to be.
Transport Systems in Animals
7.4 Circulatory Systems (cont.)
• Insects, crabs, and other arthropods have an open
circulatory system, in which there is no separation
between blood and other intercellular fluid.
Transport Systems in Animals
7.4 Circulatory Systems (cont.)
• An earthworm has a closed circulatory
system, which means that the blood is
confined to vessels.
• Blood travels through a closed circulatory system
more rapidly than it flows through an open system.
Transport Systems in Animals
7.5 Circulation in Vertebrates
• Humans and other
vertebrates have a closed
circulatory system, also called
the cardiovascular system.
• The components of the
cardiovascular system are
the heart, blood vessels,
and blood.
Blood with a high concentration of
oxygen is shown in red. Blood with
a low concentration of oxygen is
shown in blue.
Transport Systems in Animals
7.5 Circulation in Vertebrates (cont.)
• The vertebrate heart consists
of one or more atria,
chambers that receive blood
returning to the heart, and
one or more ventricles,
chambers that pump blood
out of the heart.
Transport Systems in Animals
7.5 Circulation in Vertebrates (cont.)
• There are three types of
blood vessels:
– Arteries carry blood away from
the heart to organs throughout
the body.
– Capillaries are the network
of microscopic vessels that
infiltrate every tissue.
– Veins return blood to the heart.
This scanning electron micrograph,
x100, of human capillaries lines the
wall of the gall bladder.
Arteries and veins connect with
capillaries by way of smaller
vessels or connecting channels.
Blood can pass from arteries to
connecting channels to capillaries
or directly through the connecting
channels to veins.
Transport Systems in Animals
7.5 Circulation in Vertebrates (cont.)
• Fish have a two-chambered
heart with one atrium and
one ventricle.
Transport Systems in Animals
7.5 Circulation in Vertebrates (cont.)
• Amphibians and most
reptiles have a threechambered heart with two
atria and one ventricle.
• Oxygenated and
deoxygenated blood
continually mix in the single
ventricle, lowering the level
of oxygen reaching the
organs of the body.
Transport Systems in Animals
7.5 Circulation in Vertebrates (cont.)
• The four-chambered heart
found in mammals, birds, and
crocodilians has two atria and
two completely divided
ventricles.
• This double circulation
system keeps oxygenated
blood completely separate
from deoxygenated blood
which delivers high levels
of oxygen.
Transport Systems in Animals
7.6 The Human Heart
• Each heartbeat is a sequence of muscle
contraction and relaxation called the cardiac cycle.
• In each cycle, the four chambers of the human
heart go through phases of contraction, or systole,
and relaxation, or diastole.
Transport Systems in Animals
7.6 The Human Heart (cont.)
Blood enters the atria,
which contract, forcing
blood into the ventricles.
The atria relax
and fill.
The ventricles contract,
forcing blood into the
pulmonary artery and
the aorta. Then, the
ventricles relax and the
atria contract, repeating
the cycle.
Blood flow through the human heart
Transport Systems in Animals
7.7 Molecular Basis of Muscle Contraction
• Muscle contractions are
produced by a molecular
motor largely composed
of two proteins called
actin and myosin.
• Actin filaments are anchored
to a structure called a Z-line
at each end of the unit.
• Myosin filaments contact the
actin with rows of globular
crossbridges, which bind to
the actin.
http://media.pearsoncmg.com/bc/bc_campbell_biology_6/cipl/ins/49/HTML/source/71.html
Transport Systems in Animals
7.7 Molecular Basis of Muscle Contraction
• During contraction, these
crossbridges “ratchet”
along the actin filaments
toward the Z-lines by
continually releasing their
attachment at one point,
changing position, and
reattaching at a point
farther along.
http://media.pearsoncmg.com/bc/bc_camp
bell_biology_6/cipl/ins/49/HTML/source/71.
html
(cont.)
An enzyme uses the energy
of ATP to form cross bridges
between myosin and actin
filaments, causing the
muscle to contract.
Regulation and Transport
7.8 Blood Pressure
• Blood vessels differ in the amounts of muscle and
elastic tissue in their walls:
– The largest arteries, which are under high pressure, have
walls made up largely of muscle and other elastic tissue.
– The walls of smaller arteries are made of muscle
and elastic tissue that contract and expand to regulate
blood pressure and the flow of blood into different
parts of the body.
– Veins, which are under lower pressure, have thinner
walls with less muscle and elastic tissues than arteries.
The structure of blood vessels
Regulation and Transport
7.8 Blood Pressure (cont.)
• Valves in the veins prevent blood under lower
pressure from flowing backward.
The valves regulate the flow of
blood toward the heart. Note
that back pressure on the valve
tends to keep it closed until the
pressure of blood on the other
side opens it.
Regulation and Transport
7.8 Blood Pressure (cont.)
• Contraction of the skeletal
muscles around the veins
and gravity help to push the
blood along.
http://science.howstuffworks.com/life/29103-100greatest-discoveries-blood-flow-theory-video.htm
Movement of blood in veins is
brought about by pressure from
adjacent muscles. Compression
forces blood in both directions, but
valves prevent blood from flowing
backward and away from the heart.
Regulation and Transport
7.8 Blood Pressure (cont.)
• A healthy blood pressure
is maintained through
complex interactions
involving hormones and
the nervous, excretory,
and circulatory systems.
• Various organs and
tissues of the body
respond differently to
circulatory signals.
http://www.mayoclinic.
com/health/what-isbloodpressure/MM00783
Note the change in the distribution of
blood supply during rest and exercise.
Regulation and Transport
7.8 Blood Pressure (cont.)
• About 20% of the adult population in the United
States has blood pressure constantly higher than
the normal range. This is a condition called
hypertension.
• Hypertension can be controlled by medication
prescribed by a physician, regular physical
examinations, proper diet, and exercise.
http://www.youtube.com/watch?v=qWti317qb_w
Regulation and Transport
7.9 Composition of Blood
• Vertebrate blood contains several types of cells
suspended in a fluid.
• Specialized cells called red blood cells, or
erythrocytes, transport oxygen.
• Erythrocytes contain an oxygen-carrying red
protein called hemoglobin.
• Hemoglobin consists of four subunits, each of
which carries an iron atom suspended in an organic
molecule called a heme group.
(a) Erythrocytes moving single file
through a human capillary, x2000.
(b) Each red erythrocyte contains many
molecules of hemoglobin, x6000.
(c) Hemoglobin is a large molecule
composed of four protein subunits.
(d) Each subunit includes an ironcontaining heme molecule.
Regulation and Transport
7.9 Composition of Blood (cont.)
• The iron of heme forms a temporary chemical bond
with oxygen, which the erythrocyte transports to
body cells.
• Human erythrocytes live only about 120 days.
Replacement cells are manufactured in the
marrow, the soft tissue in the long center of the
bones of the body.
Regulation and Transport
7.9 Composition of Blood (cont.)
• Specialized white blood cells, or leukocytes,
circulate in the blood and form a line of defense
against invading organisms such as bacteria
and viruses.
• Some types of leukocytes,
called macrophages,
surround bacteria and
absorb them.
Cells visible here include erythrocytes, x400,
three types of leukocytes (left, center, and right),
and platelets (the small particle, upper left).
Regulation and Transport
7.9 Composition of Blood (cont.)
• The fluid portion of the blood, called plasma,
consists of water, proteins, dissolved ions, amino
acids, sugars, and other substances.
• Plasma transports:
– most of the carbon dioxide generated as a
waste product during cell respiration.
– digested food from the intestine.
– hormones that are secreted by glands.
Regulation and Transport
7.9 Composition of Blood (cont.)
• Dissolved ions in the plasma help maintain the
osmotic balance between the blood and the
intercellular fluid. They also help maintain the
normal pH of the blood.
• The kidneys maintain these plasma ions (also
called electrolytes) at precise concentrations.
Regulation and Transport
7.9 Composition of Blood (cont.)
• Some intercellular fluid is
recycled into the circulatory
system indirectly by the
lymphatic system.
• The fluid in the lymphatic
system, which contains
certain specialized cells,
water, large protein
molecules, salts, and other
substances, is called lymph.
http://www.youtube.com/watch?v=BX8fBlme9vQ
Regulation and Transport
7.9 Composition of Blood (cont.)
• A vital characteristic of blood is its ability to clot,
or coagulate.
• Coagulation begins when small cell fragments in
the blood, called platelets, interact with a protein
found in connective tissue that has been exposed
at a wound site.
http://www.youtube.com/watch?v=--bZUeb83uU
Regulation and Transport
7.9 Composition of Blood (cont.)
• The platelets form a plug
and release enzymes that
interact with plasma
proteins known as clotting
factors, beginning a chain
of reactions.
• The end result of the cascade
of enzymatic reactions is
creation of fibrin.
Regulation and Transport
7.9 Composition of Blood (cont.)
• Fibrin forms a network of threads that trap
additional platelets, erythrocytes, and other
materials that form the clot.
http://www.youtube.com/watc
h?v=HFNWGCx_Eu4
http://www.youtube.com/watch
?v=9QVTHDM90io
Human blood clot, x2,200
Regulation and Transport
7.9 Composition of Blood (cont.)
• Thrombin clips two
peptides from
fibrinogen, reducing the
solubility of the fibrin
molecule and exposing
sites that can bind to
other fibrin molecules.
• This causes them to link
up and form the long
strands found in the clot.
Regulation and Transport
7.9 Composition of Blood (cont.)
• Clotting is vital when wounds occur, and disorders
related to clotting can be very dangerous.
– If a clot blocks one of the arteries supplying
blood to the heart, a heart attack occurs.
– A clot that blocks an artery in the brain causes
one type of stroke.
– Problems with inadequate coagulation may be
caused by hemophilia A, a serious genetic
disorder.
Regulation and Transport
7.10 The Circulatory System and Homeostasis
• An organism’s ability to maintain homeostasis
depends on the smooth interactions of its organ
systems linked by the fluids of the transport system.
• The transport system is the essential link in
maintaining homeostasis because it carries
hormonal signals and needed materials to all
parts of the body.
Regulation and Transport
7.10 The Circulatory System and Homeostasis
(cont.)
• There are many control mechanisms that detect
subtle changes in an organism’s external
environment and that make necessary adjustments
to keep the internal environment constant.
• The gas-exchange system plays an important role
in maintaining homeostasis.
Summary
• In single-celled and simple multicellular aquatic organisms,
diffusion provides a sufficient supply of materials necessary for
life processes.
• Special structures have evolved in plants that transport raw
materials to all the cells of the plant.
• In animals, circulatory transport food and oxygen to cells and
remove waste products of cellular respiration.
• Arteries have muscular, flexible walls that withstand high blood
pressure near the heart.
• Veins are less muscular and more flexible than arteries, and
they are subjected to lower pressure.
• Exchanges of gases, wastes, and nutrients occur between the
blood and the cells through capillaries.
Summary (cont.)
• A four-chambered heart separates the systems for gas
exchange and for circulation.
• Blood consists of specialized cells, proteins, and plasma.
• Vertebrate erythrocytes contain the oxygen-carrying protein
hemoglobin.
• Leukocytes provide the second line of defense against
invading organisms.
• Some proteins function with platelets to form clots, which
repair injuries and stop blood loss.
• Some plasma and other tissue fluids are picked up and
returned to the circulatory system by the lymphatic system.
• The circulatory system functions along with the nervous,
excretory, gas-exchange, and endocrine systems in
maintaining homeostasis.
Reviewing Key Terms
Match the term on the left with the correct description.
___
xylem
b
___
actin
e
___
erythrocytes
d
___
platelets
a
___
leukocyte
f
___
phloem
c
a. small cell fragments that
facilitate clotting
b. nonliving tissue that carries
water and dissolved minerals
from the roots to the rest of a
plant
c. living cells that transport
nutrients throughout a plant
d. a red blood cell
e. a protein in muscle fiber
f.
a white blood cell
Reviewing Ideas
1. Describe the primary difference in structure
between the circulatory system in a fish with
that of a human.
Fish have a two-chambered heart and a single
system for blood flow. Humans have fourchambered hearts and double circulation in
which oxygenated blood is completely separated
from deoxygenated blood.
Reviewing Ideas
2. What is capillary action and why does it occur?
Capillary action is the phenomenon by which
water will rise up inside a tube. It occurs because
water molecules develop adhesion to charged
groups on the walls of the tube, pulling them
upward; additional water molecules are then
drawn up by cohesion.
Using Concepts
3. How are the circulatory system and the
lymphatic system codependent?
The lymphatic system recycles some of the
intercellular fluid back into the circulatory system.
Using Concepts
4. How are insects able to have an open
circulatory system and still move quickly?
Open systems work well in small animals, such as
insects, that so not transport oxygen long distances
in blood. Insects distribute oxygen through
microscopic air ducts with branches that reach
every part of the body.
Synthesize
5. Leukemia is a cancer of the bone marrow. How
would leukemia affect the body’s homeostasis?
By destroying the bone marrow, leukemia
reduces a body’s ability to replenish its supply of
erythrocytes. This leads to a decreased oxygen
carrying capacity.
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Chapter Animations
Sources and sinks in phloem transport
Blood flow through the human heart
The structure of blood vessels
Sources and sinks in phloem transport
Blood flow through the human heart
The structure of blood vessels
End of Custom Shows
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