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Circulation
Table of Contents
The Body’s Transport System
A Closer Look at Blood Vessels
Blood and Lymph
Cardiovascular Health
Circulation - The Body’s Transport System
The Cardiovascular System
The cardiovascular system
carries needed substances
to cells and carries waste
products away from cells.
The circulatory system
consists of the heart, blood
vessels and blood
In addition, blood contains
cells that fight disease.
Circulation
The Cardiovascular System
Jobs of the Cardiovascular
System
1. Deliver Needed Materials
• Blood carries oxygen to
all the cells in your body
2. Remove Waste Products
• When cells break down
glucose for energy,
carbon dioxide is released
as waste
3. Fight Disease
• Blood transports diseasefighting cells all around
your body
Circulation - The Body’s Transport System
The heart is a hollow,
muscular organ that
pumps blood
throughout the body.
The right side of the
heart is completely
separated from the
left side by a wall of
tissue called the
septum.
Each side has an
upper chamber, or
atrium, and a lower
chamber, or
ventricle.
The Heart
Circulation
Heart Structure
• The Ventricles:
• pumps blood out of the
heart
• Separated from the atria
by valves
• Valves are flaps of tissue
that prevent blood from
flowing backward
• Valves are also present
between the ventricles and
the large blood vessels that
carry blood away from the
heart
Circulation - The Body’s Transport System
The Heart
As blood flows out of the heart and toward the lungs, it
passes through a valve like the one here.
Circulation
How the Heart Works
There are two main phases of action:
1. Heart muscle relaxes while the heart fills with blood
2. Heart muscle contracts and pumps blood forward
The heart beat sound (lub-dup) is the sound of blood being
pushed forward and the valves closing shut
http://www.youtube.com/watch?v=H04d3rJCLCE
Circulation
The Force of the Ventricles
• The contraction of the left ventricle exerts more force than the
contraction of the right ventricle
• The right ventricle pumps blood only to the lungs whereas the
left ventricle pumps blood throughout the entire body
Circulation
Regulation of Heart Beat
• The Pacemaker:
• A group of heart cells that
send out signals that make
the heart muscle contract,
located in the right atrium of
the heart
• Receives signals about the
body’s oxygen needs and
adjusts the heart rate to
match
• Some people have
damaged pacemakers that
can result in slow or irregular
heart beats
Circulation - The Body’s Transport System
Two Loops
Blood circulates through
the body in two loops,
with the heart at the
center.
In the first loop, blood
travels from the heart to
the lungs and then back
to the heart.
In the second loop, blood
is pumped from the heart
throughout the body and
then returns to the heart.
Circulation - The Body’s Transport System
Heart Activity
Click the Active Art button to open a browser window and
access Active Art about the heart.
Circulation - The Body’s Transport System
Sequencing
As you read, make a cycle diagram like the one below that
shows the path that blood follows as it circulates throughout
the body. Write each step of the pathway in a separate circle.
Pathway of Blood
Right side of
heart
Body
Lungs
Left side
of heart
Circulation
End of Section:
The Body’s
Transport
System
Circulation
Section 2 Learning Objectives: A Closer
Look at Blood Vessels
• Describe the structures and functions of the arteries
• Describe the structures and functions of the capillaries
and veins
• Explain what causes blood pressure
Circulation
Blood Vessels of the Body
After leaving your heart, blood
travels in blood vessels through the
body. You have 3 types of blood
vessels
1. Arteries  carry blood away
from the heart
2. Capillaries  narrow vessels
where substances can be
exchanged between the blood and
the body cells
3. Veins  carry blood back to the
heart
Circulation
Arteries
Purpose: The left ventricle pumps blood
into the arteries that carry blood away
from the heart and into the body
Artery Structure
• Walls are very thick and have 3 cell
layers giving strength and flexibility
• Innermost: epithelial cells, smooth
• Middle: Muscle tissue
• Outermost: flexible connective tissue
Pulse
• Caused by expansion and relaxation of
artery wall
• Ventricles contract pushing blood into
circulation and causing the artery walls to
expand
Circulation
The Arteries Regulate Blood Flow
The muscle in arteries act as a
control gate. They can adjust
the amount of blood being sent to
different organs.
• When the muscle around the
artery contracts, the artery
becomes smaller
• When the muscle relaxes, the
artery opening becomes larger
• Ex: After eating meal what do
you think happens? What about
when you are running? When
you go outside on a cold day?
Where do you think the arteries
direct blood flow to?
Circulation
Capillaries
Purpose: To provide a place
where nutrients can be delivered to
cells and waste can be removed
from cells.
Q: What types of materials need to
be delivered to cells? Removed?
Diffusion: Molecules move from an
area of high concentration to an
area of low concentration (ex: blood
glucose)
Capillary Structure
• Walls are only one cell thick
Circulation
Veins
Purpose: After blood moves through the
capillaries, it enters larger blood vessels called
veins, which carry blood back to the heart.
Structure:
• Similar to arteries, veins have 3 layers
contained in their walls
• Walls of veins are much thinner than the walls
of arteries
Q: How does blood move through the veins?
1. Contraction of skeletal muscles helps move
blood back
2. Larger veins contain valves which prevent
backflow of blood
3. Breathing movements in your chest create a
squeezing pressure against veins and force
blood toward the heart
Circulation
Blood Pressure
Q: What causes blood pressure?
• Pressure is a force exerted over an
area
• Blood Pressure is the force with
which the ventricles contract
• As blood moves away from the heart,
blood pressure decreases
• Blood flowing near the heart exerts
the highest pressure, while blood
pressure in the arteries further away
from the heart is much lower
Ex: Think of a garden hose or a faucet
Circulation
Complete the Target Reading Chart on
Comparing Blood Vessels!
Circulation - A Closer Look at Blood Vessels
Blood Vessels
The walls of arteries and veins have three layers. The walls
of capillaries are only one cell thick.
Circulation - A Closer Look at Blood Vessels
Calculating a Rate
A rate is the speed at which something happens. When you
calculate a rate, you compare the number of events with the
time period in which they occur. Here’s how to calculate the
pulse rate of a person whose heart beats 142 times in two
minutes.
1. Write the comparison as a fraction:
2. Divide the numerator and the denominator by 2:
The person’s pulse rate is 71 heartbeats per minute.
Circulation - A Closer Look at Blood Vessels
Calculating a Rate
Practice Problem
Calculate your pulse rate if your heart beats 170 times in 2.5
minutes.
68 beats per minute
Circulation - A Closer Look at Blood Vessels
Artery and Vein
In this photo, you can compare the wall
of an artery with the wall of a vein.
Circulation - A Closer Look at Blood Vessels
Comparing and Contrasting
As you read, compare and contrast the three kinds of blood
vessels by completing a table like the one below.
Blood Vessel
Function
Structure of Wall
Artery
Carries blood away from
the heart
Thick wall consisting of
three cell layers with thick
muscle in the middle layer
Capillary
Exchange of materials
between the blood and
body cells
Thin walls consisting of one
cell layer
Vein
Carries blood back to the
heart
Thick walls consisting of
three cell layers with thin
muscle in the middle layer
Circulation
End of Section:
A Closer Look at
Blood Vessels
Circulation - Blood and Lymph
Blood
Blood consists of liquid plasma and three kinds of cells—red
blood cells, white blood cells, and platelets.
Circulation - Blood and Lymph
Blood Types
The marker molecules on your red blood cells determine
your blood type and the type of blood that you can safely
receive in transfusions.
Circulation - Blood and Lymph
Blood Type Distribution
The circle graph shows the
percentage of each blood type
found in the U.S. population.
Circulation - Blood and Lymph
Blood Type Distribution
Reading Graphs:
What does each edge of the
graph represent?
The percentage of each blood
type found in the United
States population
Circulation - Blood and Lymph
Blood Type Distribution
Interpreting Data:
Rank the four major blood
types—A, B, AB, and O—
from least common to most
common. What is the
percentage of each type?
AB (4%), B (11%), A (40%),
O (45%)
Circulation - Blood and Lymph
Blood Type Distribution
Calculating:
According to the graph, what
percentage of the population
is Rh positive? What
percentage is Rh negative?
84%; 16%
Circulation - Blood and Lymph
Blood Type Distribution
Predicting:
What type of blood can
someone who is B negative
(blood type B and Rh
negative) receive? What
percentage of the population
does that represent?
O negative or B negative
blood; 9%
Circulation - Blood and Lymph
Blood Type Distribution
Creating Data Tables:
Use the data to make a table
of the eight possible blood
types. Include columns for the
A, B, AB, and O blood types;
Rh factor (positive or
negative); and percentage of
the population.
The data should be arranged
in three columns and eight
rows.
Circulation - Blood and Lymph
The Lymphatic System
The lymphatic system is a network of
veinlike vessels that returns the fluid to the
bloodstream.
Circulation - Blood and Lymph
Identifying Main Ideas
As you read the section titled “Blood,” write the main idea in
a graphic organizer like the one below. Then write four
supporting details that give examples of the main idea.
Main Idea
Blood is made up of four components.
Detail
Detail
Plasma is the
liquid part of
blood.
Red blood
cells take up
oxygen and
deliver it to
cells in the
body.
Detail
White blood
cells fight
disease.
Detail
Platelets help
form blood
clots.
Circulation - Blood and Lymph
Blood
Click the Video button to watch a movie about blood.
Circulation - Blood and Lymph
Links on Blood
Click the SciLinks button for links on blood.
Circulation
End of Section:
Blood and
Lymph
Circulation - Cardiovascular Health
Asking Questions
Before you read, preview the red headings. In a graphic
organizer like the one below, ask a what or how question for
each heading. As you read, write answers to your questions.
Question
Cardiovascular Health
Answer
What are some
cardiovascular diseases?
Cardiovascular diseases
include atherosclerosis
and hypertension.
How can a person keep
healthy?
Exercise regularly, eat a
healthy diet, and avoid
smoking.
Circulation - Cardiovascular Health
Links on Cardiovascular Problems
Click the SciLinks button for links on cardiovascular
problems.
Circulation
End of Section:
Cardiovascular
Health
Circulation
Graphic Organizer
Loop
Side of Heart
Where Loop
Starts
Where Blood
Flows to
Where Blood
Returns to
Loop One
Right side
Lungs
Left atrium
Loop Two
Left side
Body
Right atrium
Circulation
End of Section:
Graphic Organizer