The Respiratory System: Its Parts, Functions, and 5 Fun Facts

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Updated on: Educator Review By: Michelle Connolly

The respiratory system is one of the most vital systems in your body. It works in harmony with other systems to help your entire body function properly by supplying it with oxygen through breathing.

In this article, we are going to tackle that system from different angles. First, we are going to talk about the different components of the respiratory system. Then, we are going to give you some key functions of that system. Finally, we will tell you how to keep it healthy and give you some common disorders that can affect it. You will also find five fun facts about your respiratory system at the end.

And to test yourself out on this topic, you will find a short quiz at the very end of this article.

Key points discussed in this article:

Parts of The Respiratory System

The respiratory system is divided into the following components from above downward:

1. Nose / Mouth

They take oxygen from the air and deliver it to the next station in your airway (pharynx). And being the first structures to deal with the air outside your body, they are very rich in blood supply, especially your nose. This rich blood supply allows your nose to warm and humidity that air before getting inside your body.

2. Pharynx (Throat)

This structure helps to deliver the air you breathe from your nose or mouth to the larynx. It is a common structure in both the respiratory and digestive systems.

3. Larynx (Voice box)

The larynx is a significant structure in the process of vocalization (producing sounds using the vocal cords in your larynx). But when it comes to breathing, it works as a connecting dot. It delivers the air it receives from the pharynx to the trachea (windpipe).

The epiglottis is considered part of the larynx. It is a leaf-like flap which moves downward during swallowing to close your airway and thus prevent any food or liquid from getting into your airway and causing choking.

4. Trachea (Windpipe)

A single tube-like structure that lies in between your right and left lungs. It delivers the air it receives to the next station, which is the bronchi. The trachea is lined by tiny hairs known as cilia which move in a wave-like pattern to clear away any dust or irritant substances from your airway.

5. Bronchi (Large Airways)

The bronchi (the singular of which is bronchus) are the downward extension of your trachea, and they deliver the air to the bronchioles. We have two main bronchi; the right main bronchus, which goes to the right lung, and the left main bronchus, which goes to the left lung, as its name implies.

6. Bronchioles (Small Airways)

The bronchioles are the continuation of the bronchi, and they deliver the air they receive to its final station, which is the alveoli in your lungs.

7. Lungs

The final station of the journey that air travels inside your airway. And being the final station, it is also the place where the most important function of your respiratory system takes place. It is the place where a process called gas exchange occurs. To better understand the process of gas exchange, we need to know first the macroscopic as well as the microscopic structure of your lung.

We have two lungs; one on the right side of the chest wall and the other one on the left side. They are protected inside the rib cage. The lungs are covered by a thin outer protective membrane called the pleura.

The right and left lungs are similar in structure but have some differences, including the following:

  • The left lung is divided into two lobes, while the right one has three lobes. That is why the right lung is heavier than the left one.
  • The left lung is long and narrow compared to the right lung, which is wide and short to provide enough space for the liver, which sits right underneath the diaphragm on the right side.
  • The left lung contains a deep notch known as the cardiac notch. This notch receives the heart.

Zooming in to the microscopic level, your lungs are composed of the following structures:

  • Alveoli (the singular of which is alveolus). These are tiny sacs that receive air from the bronchioles. And being the final station, it is where the process of gas exchange takes place in your lungs.
  • Small blood vessels (capillaries). They surround the alveoli inside your lung. These capillaries, together with the alveoli, are the key players in the process of gas exchange.

The process of gas exchange:

The process of gas exchange starts when you take a breath in the following order:

  • First, the oxygen you breathe in travels inside your airway all the way down to your lung alveoli.
  • Inside the alveoli, this process happens with the diffusion of oxygen from your alveolar space to the small blood vessels surrounding your alveoli. These capillaries then carry oxygen to other cells inside your body to function properly.
  • At the same time, carbon dioxide leaves your capillaries to the adjacent alveolar space and then gets expelled from your body during exhalation (breathing out).

Your respiratory system can’t function properly without some supportive structures that help it do its function. These structures are thus considered part of the respiratory system.

These supportive structures are:

  • The diaphragm: an extremely important structure in the process of breathing, as we will see later.
  • The external intercostal muscles: they play a major role with the diaphragm during normal quiet breathing.
  • The accessory muscles of respiration: these muscles, unlike the diaphragm and external intercostals, work mainly during forced breathing; for example, during exercise. They include sternocleidmastoids, scalenes, serratus anterior and posterior, latissimus dorsi, and pectoralis muscles.
  • The ribs (rib cage): they support and protect the precious organs that lie within, namely the heart and lungs.
  • Sinuses: These are hollow structures inside your skull bones. They help in warming and humidifying the air you breathe before it gets past your nose.

The Functions of The Respiratory System

We all know that your respiratory system is responsible for the processes of respiration (breathing). But this is not the whole story.

Your respiratory system does other things, including:

  • It gives you the ability to talk (your larynx is the major player in this process).
  • You can’t smell without your nose, which is a part of your respiratory system.
  • Supplies your cells with the oxygen they need to survive and function properly. In fact, your whole body owes so much to your lungs, being the organ that supplies your cells with oxygen.
  • Removes waste products from your body, mainly carbon dioxide, during the process of exhalation.

How Do We Breathe?

The mechanism of breathing is quite simple to get a grasp of.

It includes two processes:

  • Inspiration (breathing in): during this process, the diaphragm contracts. When your diaphragm contracts, it moves down to allow more air to get into your lungs. Given that your lungs are elastic, they expand and accommodate more air.
  • Expiration (breathing out): this process occurs passively due to the elastic recoil of the lungs and the relaxation of the muscles that were actively involved in the process of inspiration. Relaxation of the diaphragm means moving upward, which helps in forcing air out of the lungs (exhalation).

The following video shows you the mechanism of breathing with fun animation:

The mechanism of breathing (inspiration and expiration)

How to Keep Your Respiratory System Healthy?

The most valuable thing to do for your respiratory system is to stay away from smoking. If you avoid this one harmful habit, you will definitely save yourself tons of undesired problems in the future.

There are many other things you can do to protect your respiratory system, as follows:

  • Stay away from pollution (fumes, dust, or any irritant substance to your lungs should be avoided). You can do so by choosing a better and clean place to live. If it is not possible to do so, you can minimize the effect of these harmful substances on your lungs by wearing a mask whenever needed.
  • Wash your hands often to prevent the spread of infections.
  • Get the flu vaccine every year.
  • Other things to do to keep your lungs healthy are to eat healthy food and do regular exercise.

Some Common Conditions That Affect Your Respiratory System

In this section, we will talk briefly about some common diseases that might affect your respiratory system.

These conditions include:


This is a chronic disease that comes in the form of recurrent attacks with symptom-free periods in between these attacks. It is characterized by repeated inflammation in the airways, which leads to the narrowing of the airways and subsequent breathing difficulty. It is divided into many types according to the triggering factor; for example, it can be triggered by infections, exercise, cold air, allergic substance, seasonal changes, and so on.

To know more about the signs and symptoms of asthma or when to see a doctor, check out this article.


In some predisposed people, the entrance of specific substances like mold, dust, or pollen into their airways can cause an inflammatory reaction. This inflammatory reaction leads to the narrowing of their airways during the attack, which leads to difficulty in breathing and other associated symptoms.

Allergy is very similar to asthma in many ways, and they often occur together. It is often considered a type of asthma called allergic asthma.


Infections in your respiratory system can occur in any part of the respiratory system. They may affect the upper respiratory tract, such as the flu (common cold). They may also occur in your bronchi or bronchioles (bronchitis and bronchiolitis). Or they may take a dangerous form when occurring in your lungs(at the alveolar level), which is known as pneumonia.

Lung Cancers

This is an uncontrolled division of cells in any part of your lungs, leading to many symptoms and can also spread to other organs affecting their functions. By far, smoking is the principal risk factor for developing lung cancer. So the take-home message from this whole article is to keep smoking at bay.

Fun Facts About Your Respiratory System

Your respiratory system is full of astonishing facts. We have listed only five of them down below.

  • Your lungs are spongy in consistency which means they can float on the water’s surface.
  • The tiny hairs inside your nose (Vibrissae) work as a filter. they prevent dust and other harmful substances from entering your airway.
  • Children have higher respiratory rates than adults. Respiratory rate is the number of breaths you take per minute.
  • Your diaphragm is a unique muscle. You have two distinct types of muscles throughout your whole body: voluntary skeletal muscles and involuntary smooth muscles. But the diaphragm can work as both a voluntary muscle (you can decide when to take a deep breath and hold it or release it) and an involuntary muscle (this is crucially important for you during sleep to keep your diaphragm moving so that you won’t stop breathing and stay alive). This is the only muscle in your whole body that can work both voluntarily and involuntarily.
  • As you exhale (breathe out), you don’t get rid of all the air inside your lungs. In fact, there’s a minimal amount of air that is left inside your alveoli even after complete forced expiration. This volume is about 1200 ml and is known as the residual volume.


Now it’s time to take a deep breath and relax as the story of your respiratory system has come to an end. And while you breathe in and out, don’t forget to track your chest wall and detect how your chest moves up and down with respiration.

Next time when someone asks you about anything related to the respiratory system like: what are the parts of the respiratory system, how we breathe, how gas exchange occurs inside our lungs, what is asthma, or how to keep our lungs healthy, you will be ready to give them accurate answers.

A short quiz on the topic.

Q (1). All of the following are components of your respiratory system except:

  1. The nose/ mouth.
  2. The larynx.
  3. The trachea (windpipe).
  4. The oesophagus.

Q (2). Which of the following is not considered a function of the respiratory system?

  1. Supplies your body with oxygen.
  2. Helps you get rid of waste products like carbon dioxide.
  3. Regulates your body temperature.
  4. Allows you to talk.

Q (3). During the process of inhalation (breathing in), which of the following is correct:

  1. The diaphragm moves up.
  2. The lungs collapse.
  3. The diaphragm moves down.
  4. The air gets out of your respiratory system.

Q (4). During the process of exhalation (breathing out), which of the following is false:

  1. The lungs collapse.
  2. The air gets out of your respiratory system.
  3. The diaphragm moves up.
  4. The diaphragm moves down.

Q (5). To keep your respiratory system healthy, you should do the following except:

  1. Smoke.
  2. Wash your hands frequently.
  3. Get the flu vaccine each year.
  4. Wear a mask in highly polluted places.

Q (6). Choose the correct order that air takes to travel down through your airway

  1. Nose – pharynx – trachea – larynx – lungs – bronchi – bronchioles.
  2. Pharynx – larynx – trachea – nose – bronchi – bronchioles – lungs.
  3. Nose – pharynx – larynx – trachea – bronchioles – bronchi – lungs.
  4. Nose – pharynx – larynx – trachea – bronchi – bronchioles – lungs.

Q (7). All of the following regarding your lungs are false except:

  1. They are covered by a thin outer protective layer called the peritoneum.
  2. The right lung has only two lobes, while the left one has three.
  3. The functional units of your lungs that do the gas exchange process are the alveoli.
  4. The right and left lungs are identical and can’t be differentiated from each other.

Q (8). During the process of gas exchange inside your alveoli, which of the following happens?

  1. Oxygen diffuses into your alveoli and then gets out of your airways during exhalation.
  2. Carbon dioxide gets into your capillaries and then gets distributed throughout your whole body.
  3. The exchange of carbon dioxide occurs minutes after oxygen exchange inside your alveoli.
  4. Carbon dioxide and oxygen exchange occur simultaneously inside your alveoli.

Q (9). This structure prevents any food or liquid from getting into your airway.

  1. The epiglottis.
  2. The larynx (voice box).
  3. The bronchioles (small airways)
  4. The bronchi (large airways)

Q (10). Which of the following does not happen during the process of gas exchange inside your lung alveoli?

  1. Carbon dioxide gets into your capillaries and then gets distributed throughout your whole body.
  2. Oxygen is carried from the capillaries inside your lungs to all other organs and tissues to use it.
  3. Carbon dioxide and oxygen exchange occur simultaneously inside your alveolar space.
  4. Carbon dioxide moves from your capillaries to the alveolar space and then gets out of your airway during exhalation.

The correct answers:

Q (1) – 4

Q (2) – 3

Q (3) – 3

Q (4) – 4

Q (5) – 1

Q (6) – 4

Q (7) – 3

Q (8) – 4

Q (9) – 1

Q (10) – 1

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