Respiratory System 7 Tasks for Review


Your body is made up of trillions of living cells. Each of these cells needs energy to carry out the various tasks that keep our bodies alive and functioning. The circulatory system delivers food that has been broken down by the digestive system to every living cell in the body. To use that food and release the energy stored in the food, the cells need a gas called oxygen. The cells can only burn the food and release the energy when oxygen is present. This process is called respiration and is essential to almost everyform of plant and animal life on earth.

       Most animals that live in the water get the oxygen they need with the help of gills. You can see the gills on the side of a fish’s head. These feather-like gills are capable of absorbing oxygen that is dissolved in the water and releasing it into the fish’s blood.

Insects take in oxygen through small holes on the sides of their abdomens called spiracles. You can see these little holes in nice lines on both sides of this insect’s body. They lead to tubes that carry the oxygen to internal organs.

Mammals, which include humans, have very complex respiratory systems. They get their oxygen from the air that surrounds our planet. The air is made up of 78 percent nitrogen and 21 percent oxygen. The other 1 percent includes argon, carbon dioxide, water vapor, and some other gases in very small amounts. The air is breathed in and goes to lungs, which exchange the oxygen for a waste product called carbon dioxide. Some mammals that live in the water, such as dolphins and whales, breathe through blowholes on the tops of their heads. They must surface regularly to take in new supplies of air and to release the waste products of respiration.


Let's look closely at the human respiratory system. Air typically enters the body through the nostrils of the nose. Small hairs just inside the nostrils may stop some of the unwanted dust and dirt particles found in the air. The air moves from the nostrils into the two nasal cavities of the nose. A wall of cartilage and bone separates the two cavities. The air is heated at this point by warm blood flowing through blood vessels in the nasal cavities. This acts like a radiator. Air taken in through the nose is warmed before going to the lungs. Air can also be brought into the body through the mouth, but here there are fewer opportunities for dust and dirt particles to be removed, and there will not be this warming process. Try this experiment to see the difference in air temperature as it enters the body. Breathe with your mouth closed and through your nose. Then purposely breathe with your mouth as if your nose was stuffed up. The air that you breathe in through the mouth will feel cooler at the back of your throat.

The nose produces a continuous supply of mucus. This mucus, which is replaced every 20 minutes, has two main jobs. One is to add some moisture to the air so that the internal tissues of the respiratory system don’t dry out. The other job is to catch unwanted particles and bacteria from the air. The unwanted particles are caught in the mucus and then billions of small hair-like structures called cilia

move the mucus into the esophagus that leads to the stomach. The stomach releases digestive juices that contain hydrochloric acid. This acid destroys the foreign material.

Sometimes the particles caught in the mucus of the nasal cavities irritate the nose and causes sneezing. This is another way to release unwanted particles from the body.

You can see it is best to breathe through the nose because of the warming, filtering, and moistening of the air. From the nose, the air travels into the throat. At one point, the throat leads to two separate paths. One is the esophagus, which is the tube leading to the stomach. The other is the trachea, a tube leading to the lungs. At the top of the trachea is a small flap called the epiglottis. This flap covers the opening to the trachea so that food won’t go into the trachea when you swallow. When we breathe, the flap opens to allow the air to enter the trachea and the rest of the respiratory system.


At the top of the trachea is the larynx, which contains the vocal cords. Two small folds of tissue are stretched across the larynx with a small gap between them. When we talk,

the muscles of the larynx tighten the tissue, making the opening smaller. As air from the lungs goes past the opening, the vocal cords vibrate, making sounds. The pitch of a

sound is determined by the size of the larynx and the length of the vocal cords. Because men have larger larynxes and longer vocal cords, their voices are usually lower than women’s. The shorter vocal cords of a female vibrate faster so the sound has a higher pitch. You can feel your trachea and find the location of your larynx. With a finger, rub gently on the front of your neck and you will feel a tube-like structure with bumps. This is your trachea or windpipe. What you feel as bumps are actually bands of cartilage that support the trachea. The larynx is made of a piece of cartilage that is larger than the other cartilage in the trachea. On a male, you can easily see this cartilage sticking out. It is referred to as the “Adam’s apple.” Some people think that only males have Adam’s apples, but actually everyone has an Adam’s apple. Only the larynx on a male is larger than a female’s, so the Adam’s apple shows up clearly on males but is not very noticeable on females.





When air enters the trachea, there is another round of mucus found in the lining of this passageway. If dust particles have made it this far, they may be caught in this mucus before moving into the sensitive and delicate lungs. Dust that is trapped by this mucus can be sent back up to the mouth or nose by the movement of small cilia, or a person may cough to remove the mucus and foreign matter. The trachea branches into two paths before entering the lungs. These branches are called the left and right bronchi. Inside the lungs, the bronchi divide into smaller and smaller branches. At the end of the smallest branches are clusters of hundreds of round sacs called alveoli. They resemble grapes on a vine. The body has about 600 million alveoli. It is here that the exchange of gases takes place. Each alveolus has tiny blood vessels called capillaries running

around it. When the oxygen-rich air enters the lungs and travels to the millions of alveoli, the oxygen passes through the cell walls of the alveoli into the capillaries of the circulation system. The blood picks up the oxygen and releases to the alveoli carbon dioxide, the waste product carried from the body’s living cells.  Blood which contains carbon dioxide from the cells of the body will appear blue, while blood rich with fresh oxygen will be red. This exchange must happen quickly, so that is why there are so many of these little exchange sacs. They allow for a greater area for exposure to capillaries. If the material that makes up all the alveoli in your two lungs were spread out flat, it would cover an area the size of a tennis court



A newborn baby takes about 40 breaths each minute. A one-year-old child takes about 24 breaths per minute. An adult takes about 14 breaths per minute. However, during exercise, the rate can increase to over 100 breaths per minute. Adults breathe in about seven to ten liters of air each minute. It is our brains that control the breathing process. We don’t have to think about breathing, it is automatic. The control center for breathing is found in the brain stem. It uses information from various parts of the body concerning the levels of carbon dioxide and oxygen in the blood. Based on the comparison of carbon dioxide and oxygen levels, the brain sends electrical signals to the diaphragm and chest muscles, which cause us to breathe in and out. To bring air into our bodies, the diaphragm, which is a bell shaped sheet of muscle, contracts. This causes it to flatten, creating a larger area in the chest cavity and, as a result, a space of low air pressure. Air rushes in through the nose and trachea to fill the lungs and expand them to fill up some of this low-pressure area. When the diaphragm relaxes, it moves back into its normal bell-shaped position, which causes the chest cavity to shrink and push air out of the lungs. The lungs actually are responding to the change in pressure around them. The diaphragm and muscles of the rib cage are what cause breathing to take place. Here is a simple demonstration of how the diaphragm does its job. We will cut the bottom off this 2-liter plastic bottle. A mouth of a balloon is cut away. This balloon is then stretched over the bottom of the bottle and secured with a rubber band. A second balloon is slipped through the mouth of the bottle and held in place. Now when the balloon, which represents the diaphragm, is pulled down, notice what happens to the other balloon, which represents a lung. When the diaphragm balloon is moved back to its normal position, notice that the lung releases air, just like a lung exhaling. Thank goodness that the act of breathing is an automatic operation and requires no thought. If you hold your breath, after a short period of time, you automatically start gasping for breath. Your body needs a constant supply of oxygen. You are breathing while awake and while asleep. During sleeping, the breathing rate slows down because there is not as much of a demand for oxygen. Muscles are at rest and there is less carbon dioxide being produced than during a period of high activity. Breathing during sleep is slower and more relaxed.




The respiratory system works with the circulatory system to transport oxygen to the cells and to return carbon dioxide to the lungs for elimination from the body. The heart sends blood that has returned through veins from all over the body into the lungs. This blood is carrying carbon dioxide which it will release into the alveoli. Then oxygen from recently inhaled air will pass through the cell walls of the alveoli and capillaries into the blood. The blood will continue back to the heart, where it receives its push to travel to various parts of the body. As the blood moves into capillaries, it passes by individual living cells, where the gas exchange occurs. Oxygen goes into the cell and carbon dioxide goes into the blood. This exchange takes place in the alveoli and body cells because gases tend to move from areas of concentration into areas of less concentration. What this means is that because the blood entering the lung is carrying carbon dioxide and there are lower amounts of that gas in the alveoli, the gas moves through the capillary and alveoli cell walls and into the area of lower

concentration. The same thing happens to the oxygen in the alveoli as it moves into the blood stream. This also accounts for the passage of gases from the capillaries into the cells and from the cells into the capillaries. The respiratory system is very important to our survival. Being deprived of oxygen for just a few minutes can mean great damage to the body. After a few minutes of lack of oxygen, the brain begins to suffer. If a lack of oxygen persists, death can soon follow. We can survive for days without food or water, but if deprived of oxygen, we can only survive for a few minutes.





You want to maintain a healthy respiratory system. Exercise regularly and avoid situations that are health risks. Exercise helps to build up the diaphragm muscle and to keep it strong. As you are probably aware, the leading preventable cause of lung cancer is the use of smoking tobacco. Smoking causes many problems for the human body. One of the most obvious is the damage chemicals inside cigarettes do to the lungs and the respiratory system. Nicotine in cigarettes is a chemical that is addictive and causes the body to crave it. This makes it very difficult for people to stop smoking. Their bodies have become used to the nicotine and are addicted to that chemical. Another substance released into the body while smoking is carbon monoxide. This is a dangerous gas because it takes the place of oxygen in the blood. In fact, the hemoglobin in the blood that carries the oxygen throughout the circulatory system is more attracted to carbon monoxide than to oxygen. This means less oxygen is transported to the cells and tissues of the body, which can lead to harmful effects. Tar is another damaging substance found in cigarette smoke. The tar enters the lungs in a vapor form but then

liquefies inside the lungs, where it can clog passageways and kill cilia. You may have seen roofers using tar on roof tops for buildings and offices. Each day the number of people who die from lung cancer due to smoking in the United States is equal to the total number of passengers on two 747 super jets. That is almost 1,000 people. Every year, over 400,000 people in the United States die from the effects of smoking. People who smoke are twice as likely to die from heart disease as non-smokers. They are ten times more likely to develop cancer of the throat and mouth. They are twenty-five times more likely to develop lung cancer that leads to death. Smokers have a greater chance of developing colds, coughs, and other respiratory problems. The good news is that it is possible to stop smoking and almost a million people successfully stop each year. The other good news is that if a person stops, his or her body will begin a healing process that can improve the health of their lungs over a period of years. The best idea is not to smoke at all. In fact, it would be a good idea to avoid any situations in which the quality of the air that is inhaled into your living body is questionable. Stay away from polluted air with the same intentions that would stop you from swimming in polluted water. After all, it is the health of your body and the trillions of living cells that help it to function properly that we’re talking about here.



Task 1

The Respiratory System

  1. Compare the different ways in which organisms get oxygen. (You may use a double T chart)






  1. Use a pie chart graph to display your understanding of how the gases that make up our atmosphere are broken up.





Task 2

Human Respiratory System

  1. Compare how breathing through the mouth and nose are different.




  1. Summarize the function of mucus found in the lining of your nose.


  1. Discuss the connection between the respiratory system and the stomach.



  1. Discuss the design of the epiglottis.

Task 3


  1. Compare the vocal cord of a female to those of a male.


  1. Discuss the function of the larynx.


  1. What is an “Adam’s Apple”?



  1. Discuss what determines the pitch of a sound.





Task 4

Trachea and Alveoli

  1. What is mucus?

  2. Discuss the benefits of mucus.


  3. Where are cilia found in the respiratory system?

  4. Discuss how foreign matter can find its way out of the respiratory system.


  5. Discuss what cilia are and how they are important if you live in a dusty environment.

  6. Trace the path that air takes after leaving the trachea.

  7. If a person’s alveoli’s are damaged, explain how will it affect a person’s respiratory system?

Task 5


  1. Discuss what factor influences the brain to tell the respiratory system how fast to function


  2. Discuss what causes the brain to tell our respiratory system to breathe in and out.



  3. Draw two picture of the diaphragm. One showing it when you inhale and one showing it when you exhale.

  4. What change is the lungs responding to when breathing is taking place?

  5. How is your breathing rate during sleep different from when you are awake?



Task 6

Respiratory System

  1. Describe how the respiratory system and the circulatory system work together.


  2. Discuss how alveoli plays a role in the process of oxygen and CO2 exchange.



  3. What exchange takes place in the alveoli?


  4. Describe how lack of oxygen could affect your body.






Task 7

A Healthy Respiratory System

  1. Identify the leading preventable cause of lung cancer.

  2. What role does Nicotine play in cigarettes?

  3. Why is Carbon Monoxide so dangerous in cigarette smoke?

  4. Discuss how our cells are affected by the presence of Carbon Monoxide.

  5. Discuss what tar is and how it affects the lungs.

  6. Discuss the statistics of smoker’s health.



  7. Do you think you will smoke??? Explain why