Introduction
The Respiratory System
Learning Objectives
- Know the basic components of the conducting and respiratory portion of the respiratory system and describe distinctive structural features of each component related to its particular function in respiration.
- Know the types of cells present in the respiratory epithelium and their functions.
- Be able to identify the trachea, bronchi, bronchioles/terminal bronchioles, respiratory bronchioles, alveolar ducts and alveoli on the basis of epithelial cell types present, and relative amounts of glands, cartilage, smooth muscles, and connective tissue fibers present in the wall of the tubes
What is the respiratory system?
Your respiratory system is the organs and structures in your body that allow you to breathe. It includes your lungs, nose, mouth and the tubelike structures (airways) that connect them. You also have muscles and blood vessels that support your respiratory system, and ribs to protect it. These parts work together to bring oxygen into your body when you inhale and get rid of carbon dioxide when you exhale.
Function
What is the main function of your respiratory system?
The main function of your respiratory system is to pull in oxygen for your body’s cells and get rid of carbon dioxide, a waste product. You do this by breathing in and out and through gas exchange between the small air sacs of your lungs (alveoli) and the blood vessels running nearby. Your respiratory system also:
Warms and adds moisture to the air you breathe in. Your respiratory system warms the air to match your body temperature. It moisturizes the air to bring it to the humidity level your body needs.
Protects your body from particles you breathe in. Parts of your respiratory system can block harmful germs and irritants from getting in — or push them out if they do get in.
Allows you to talk. Air vibrates your vocal cords, which makes sounds.
Helps you smell. Breathing in air moves its molecules past your olfactory nerve, which sends messages to your brain about the way something smells.
Balances level of acidity in your body. Too much carbon dioxide lowers your blood’s pH, making it acidic. By removing carbon dioxide, your respiratory system helps maintain the acid-base balance in your body.
Anatomy
What are the parts of the respiratory system?
The main organs of your respiratory system are your lungs. But your respiratory system has many different parts that work together to help you breathe. Parts of your respiratory system include your:
Nose and nasal cavity.
Mouth and oral cavity.
Sinuses.
Pharynx (throat).
Larynx (voice box).
Trachea (windpipe).
Bronchi (large airways).
Lungs.
Diaphragm.
What’s your upper respiratory tract?
Your upper respiratory tract brings air into your body and helps move it toward your lungs. It adds moisture to the air you breathe in. Your respiratory tract starts with your nose and mouth, where you pull air into your body. Other parts of your upper respiratory tract include your nasal cavity, sinuses (hollow areas in your cheeks and forehead) and larynx.
What’s your lower respiratory tract?
Your lower respiratory tract consists of your trachea, bronchi and lungs. Your trachea, bronchi and bronchioles (small airways) make up your tracheobronchial (pronounced “tray-key-oh-BRON-key-uhl”) tree, a series of increasingly smaller tubes that transport air from your upper respiratory tract to small air sacs in your lungs (alveoli). (It looks a bit like an upside-down tree.)
How does your respiratory system work?
Your cells need oxygen to create energy. Creating energy releases carbon dioxide as a waste product, which can harm your body if too much builds up. The main job of your respiratory system is to bring oxygen into your lungs and move carbon dioxide out of them (gas exchange). It works closely with your circulatory system — your heart, blood and blood vessels — to do this.
Think of the oxygen in the air as passengers on millions of planes flying into your lungs every time you breathe in. Your diaphragm pulls down, creating more space in your chest, which pulls air (and its tiny oxygen cargo) into your lungs. The air travels through your mouth or nose and down your trachea, bronchi and bronchioles, like airport runways. Then the passengers arrive at the airport gates, your alveoli.
There, the oxygen moves through the membranes surrounding your lungs into small blood vessels (capillaries). You can imagine it like the oxygen passengers getting picked up by a taxi at the airport. Finally, the taxi travels out to your tissues, dropping off oxygen to give your cells energy.
Task
I. Make a Model of the Respiratory System
Students explore the inhalation/exhalation process that occurs in the lungs during respiration. Using everyday materials, each student team creates a model pair of lungs.
Process
Materials List
Each group needs:
- 2-liter empty plastic bottle with cap
- 2 plastic drinking straws; available inexpensively at restaurant supply stores or donated by fast-food chains; do not use the flexible drinking straws
- 2 9-inch balloons
- 1 larger balloon; for example, for a punch ball
- 2 rubber bands
- Lung worksheet/student
Procedure
Before the Activity
- Gather materials and make copies of the Lung Worksheet
- In each of the 2-liter bottle caps, drill 2 holes that are just big enough for a drinking straw to fit through. Tip: Make sure to drill the holes far enough apart that the holes do not become one big hole!
- Using a pair of scissors, cut off the bottom of each 2-liter bottle.
With the Students
- Peel off the labels, if any, on the 2-liter bottles.
- Tell students that the 2-liter bottle represents the human chest cavity.
- Stick two drinking straws through the two holes in the bottle cap.
- Place one 9-inch balloon on the end of each straw and secure them with rubber bands, as shown in Figure 2.
- Tell students that the straws represent the bronchi and the balloons represent the lungs.
- Stick the balloon ends of the straws through the bottle opening and tightly screw on the lid.
- Stretch out the larger balloon and place it over the open bottom of the bottle.
- Tell students that this larger balloon represents the diaphragm. Now they have a finished model of the lungs! (See Figure 3,) Next, it is time to make the lungs work!
- Pull the diaphragm (balloon) down (that is, away from the lungs) in order to inflate the lungs. (Note: This makes the chest cavity larger and decreases the pressure.)
- Push the diaphragm (balloon) in (towards the lungs) in order to deflate the lungs. (Note: This makes the chest cavity smaller and increases the pressure.)
- Have students complete the worksheet.
- To conclude, have teams make presentations of their model lungs, as described in the Assessment section.
Evaluation
Pre-Activity Assessment
Discussion Questions: Solicit, integrate and summarize student responses.
- How do the lungs work? How do you inhale and exhale?
- Does your breathing change when you exercise? How?
Activity Embedded Assessment
Worksheet: Have students record their observations and complete the Lung Worksheet. Review their answers to gauge their mastery of the subject.
Post-Activity Assessment
Presentation and Informal Discussion: Have one or more groups use their projects to demonstrate how the lungs work. Next, hypothesize with the class: What would happen to the respiratory system if we punctured it? Have one group puncture the cavity (bottle) or diaphragm (rubber bottom) and demonstrate what happens to the lungs if this body part is damaged. (Answer: The lungs are unable to inflate and/or deflate if the chest cavity has a leak. The lungs cannot maintain the pressure difference.) Discuss with the class: What could engineers do to help fix a puncture in a person's lungs?
Conclusion
Your respiratory system is made up of your lungs, airways (trachea, bronchi and bronchioles), diaphragm, voice box, throat, nose and mouth. Its main function is to breathe in oxygen and breathe out carbon dioxide. It also helps protect you from harmful particles and germs and allows you to smell and speak.
Credits
Teacher Page
Jhetty Bird C. Batiancila