Each person has hundreds of millions of alveoli in their lungs. This network of alveoli, bronchioles, and bronchi is known as the bronchial tree. The lungs also contain elastic tissues that allow them to inflate and deflate without losing shape.
They're covered by a thin lining called the pleura pronounced: PLUR-uh. The chest cavity, or thorax pronounced: THOR-aks , is the airtight box that houses the bronchial tree, lungs, heart, and other structures.
The top and sides of the thorax are formed by the ribs and attached muscles, and the bottom is formed by a large muscle called the diaphragm pronounced: DYE-uh-fram. The chest walls form a protective cage around the lungs and other contents of the chest cavity. The cells in our bodies need oxygen to stay alive. Carbon dioxide is made in our bodies as cells do their jobs.
The lungs and respiratory system allow oxygen in the air to be taken into the body, while also letting the body get rid of carbon dioxide in the air breathed out.
When you breathe in, the diaphragm moves downward toward the abdomen, and the rib muscles pull the ribs upward and outward. The Manual was first published in as a service to the community. Learn more about our commitment to Global Medical Knowledge. This site complies with the HONcode standard for trustworthy health information: verify here. Common Health Topics.
Biology of the Lungs and Airways. Test your knowledge. Asbestosis is widespread scarring of lung tissue caused by breathing asbestos dust. Which of the following is responsible for the largest number of lung cancer cases among people with asbestosis? More Content. Click here for the Professional Version.
Gas Exchange Between Alveolar Spaces and Capillaries The function of the respiratory system is to move two gases: oxygen and carbon dioxide. Ventilation is the process by which air moves in and out of the lungs. Fold the neck of the balloon over the top of the bottle. The balloon represents a lung. Turn the bottle over keeping the balloon inside so the bottle top rests on the table.
In the next steps you will create and add the diaphragm to your model. Make a knot in the neck of the second balloon. At the opposite side of this balloon cut off about a third of the balloon so you are left with a wide opening. Stretch the wide opening of the cut balloon over the wide opening of the bottle.
Pull the edges of the balloon far enough up the bottle so the balloon surface is gently stretched. Make sure that the knot is on the outside and located near the middle of the bottle opening. Like an inflated balloon our lungs are full of air. We have two lungs, which are enclosed in the ribcage and protected by 24 ribs. When you breathe in, air flows into your lungs.
When you breathe out, air flows out of your lungs. The balloon inside the bottle is like one of your lungs. The bottle is like your ribcage. Procedure Hold the bottle so you can see the balloon inside representing the lung.
Gently pull down on the knot. What happens to the balloon inside the bottle? Let the knot come back to its neutral position and then gently push it in. What happens to the balloon inside the bottle now? Repeat these steps a few times.
Does this resemble breathing? Which part resembles breathing in and which part resembles breathing out? If your model is working well, air will rush into the balloon when you pull the knot outward and flow out when you push the knot inward. Why do you think this happens? When we breathe in a relaxed way our diaphragm—the muscle that separates the chest cavity from the abdominal cavity—moves to expand and contract the chest cavity.
How is that similar to what you do with your model? Push and pull the knot a few more times. Using the model can you find which movement of the diaphragm creates inhalation and which creates exhalation? These are called alveoli. They inflate when a person inhales and deflate when a person exhales. During gas exchange oxygen moves from the lungs to the bloodstream.
At the same time carbon dioxide passes from the blood to the lungs. This happens in the lungs between the alveoli and a network of tiny blood vessels called capillaries, which are located in the walls of the alveoli.
Here you see red blood cells traveling through the capillaries.
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