The document contains three passages about the human circulatory system: 1) It describes the four chambers of the heart and how blood flows through each. 2) It illustrates and labels the major blood vessels and pathways that move blood between the heart, lungs, and body. 3) It defines the three types of blood vessels - arteries, veins, and capillaries - and explains their structures and functions in transporting blood and nutrients around the body.

1. Name____________________________ Class__________________ Date __________
© Pearson Education, Inc., publishing as Pearson Prentice Hall.
367
The Human Heart
The human heart has four chambers: right atrium, right ventricle,
left atrium, and left ventricle. Blood flows from the body into the
right atrium. Valves keep blood flowing in only one direction.
Follow the prompts to identify parts of the human heart. The diagram
shows the heart as if viewed from the front, so left and right are switched.
• Color the left atrium orange.
• Color the left ventricle red.
• Color the right atrium yellow.
• Color the right ventricle blue.
to body
from upper
body
from lungs
(orange)
(red)
(blue)
(yellow)
Use the diagram to answer the question.
1. A valve is located between the right atrium and the right
ventricle. What is the role of valves in the heart?
to keep blood flowing in one direction

2. Name____________________________ Class__________________ Date __________
© Pearson Education, Inc., publishing as Pearson Prentice Hall.
368
The Circulatory System
The human circulatory system moves blood through two primary
pathways. One connects the heart and lungs, and the other con-
nects the heart and the rest of the body.
Draw arrows to show how blood moves through the circulatory system.
One has been drawn for you.
Capillaries of
head and arms
Aorta Pulmonary
artery
Capillaries of
left lung
Capillaries of
abdominal organs
and legs
Inferior
vena cava
Pulmonary
vein
Capillaries of
right lung
Superior
vena cava
Use the diagram to answer the question.
1. Through which blood vessel does blood return to the heart
from the head and arms?
through the superior vena cava

3. Name____________________________ Class__________________ Date __________
© Pearson Education, Inc., publishing as Pearson Prentice Hall.
369
Blood Vessels
As blood flows through the body, it passes through three types of
blood vessels—arteries, veins, and capillaries.
Complete the table. Fill in the missing information.
Use the table to answer the questions.
1. Which are the smallest blood vessels? Circle the correct answer.
capillaries veins
2. How does exercise help veins function?
Blood Vessels Structure Function
arteries thick walls containing carry blood away
connective tissue, from the heart
endothelium, and
smooth muscle
veins walls containing carry blood toward
connective tissue, the heart
endothelium, and
smooth muscle;
large ones also have
valves to control the
direction of blood flow
capillaries walls only one cell thick; bring nutrients and
most so narrow that oxygen to cells
blood cells pass through and remove
in single file carbon dioxide
and waste
Contracting muscles help blood move through veins toward the heart.