Download The Respiratory System

The Respiratory System
The respiratory system brings oxygen from the air into the blood and returns carbon dioxide from the
blood to the air. The respiratory system works very closely with the circulatory system to provide cells
with oxygen, and to remove waste carbon dioxide produced by the activities of cells.
1. The main function of the respiratory system is to____________________________________
___________________________________________________________________________.
Directions: Trace the pathway of air on the diagram as you read the passage below. Follow the
directions to make a color key for the respiratory system.

When you breathe, air enters the respiratory system through the nose. The lining of the nose
produces mucus, which moistens air and traps germs and dirt and is lined with hairs to remove
dust and dirt from the air.
2. What is a common name for mucus?_______________________________________________
3. What is the function of mucus in the nose?__________________________________________

Air from the nose travels to the throat, and then goes through the trachea or windpipe. A flap
called the epiglottis covers the windpipe to prevent food and water from entering the trachea.
4. Describe the function of the epiglottis______________________________________________


The trachea branches off into two smaller tubes called bronchi, which lead to a lung through
smaller and smaller branches called bronchioles.
The air then enters the tiny air sacs called alveoli where the blood picks up oxygen and then gets
rid of carbon dioxide.
5. The tiny sacs in the lungs where oxygen and carbon dioxide enter and leave the lungs are
called ______________________________.
 The lungs do not take in air by themselves. Breathing is caused by the actions of muscles in the
ribs, diaphragm, and abdomen to draw in oxygenated air by making the chest cavity larger. As
the chest cavity gets larger, the air pressure gets lower inside the chest and lungs. Air rushes
into the lungs to equalize the air pressure. We breathe out carbon dioxide when the ribs move
in and the diaphragm moves upward. This makes the chest cavity smaller which forces out of
the lungs because of the increase in air pressure. All of these actions take place without us
thinking about it, because breathing is an involuntary action controlled by the nervous system.
6. Muscle contractions in the _________________, ___________________ and
___________________ cause us to breathe in and out.
7. Another word for breathe in is ______________________________.
8. Another word for breathe out is _____________________________.
 Once in the lungs, the oxygen in the air passes across the thin membranes of the alveoli sacs in
the lungs, and into the alveoli sacs in the lungs, and into the oxygen-poor blood in the tiny
capillaries that surround the sacs. The thin-walled capillaries are so narrow that they can hold
red blood cells in a single line.
9.
Alveoli sacs are surrounded by
__________________________________ which are so narrow (thin) they can
hold____________________________________________________________.
The Circulatory System
The red blood cells contain hemoglobin, an iron-containing material that can combine easily
with oxygen or carbon dioxide. Oxygen moves from the alveoli into the blood and carbon
dioxide moves from the blood into the alveoli. The newly oxygenated blood flows back to the
left atrium by the pulmonary vein, and then it is pumped by the left ventricle into the aorta.
The circulatory system works closely with the respiratory, digestive and excretory systems to
transport nutrients and to remove wastes from cells in all parts of the body. The heart, blood
vessels, and blood are the three main parts of the circulatory system, and each part has specific
structures to help perform the function of transporting materials within the body.
The heart is a fist-sized, muscular organ that the beats 70-80 times every minute that you are
alive. Each time your heart beats, it pumps about ¼ cup of blood, so each minute it pumps
about five quarts of blood. The heart’s special structure allows it to receive oxygen-poor blood
from the body, pump the blood to the lungs to pick up oxygen, and then pump oxygen rich
blood back out to the body with each beat.
The blood from the body returns to the heart in “tubes” called veins. Oxygen –poor blood
enters the right atrium of the heart through blood vessels called the superior and inferior vena
cava, which are large veins. When the heart contracts, blood is pushed into the right ventricle.
The right ventricle pumps blood out into the pulmonary arteries, which transports the blood to
the lungs.
Blood is pumped away from the heart in blood vessel “tubes” called arteries. Arteries always
carry blood away from the heart while veins carry blood to the heart.