Have you ever experienced a change of voice or a decreased sense of smell when you have a cold?

Have you ever observed that your breathing becomes faster and more laborious when you actually pay attention to it? These processes illustrate the complexity of your respiratory system. You could survive without food for days to months but if you stop breathing for five minutes or more, your brain would die. Your respiratory system has small involuntary muscles but sometimes, when you need to, you can actually control your breathing.


What are the functions of the respiratory system?

The main function of your respiratory system is for gas exchange. This involves getting oxygen from the atmosphere and expelling carbon dioxide into the environment. Additionally, this system contributes to your voice and allows you to talk, shout and sing. It also serves the sense olfaction (smelling) and allows you to enjoy different scents.

What are the parts of the respiratory system?



Your respiratory system consists of different organs. This system starts from your nose and mouth and ends in your lungs.

  • Nose: The nose is the main entry point of air. Inside the nose is a passageway called the nasal cavity. It has tiny hair called vibrissae that help filter out dirt, smoke and other nasty particles that need to be removed. It also has mucous glands that secrete mucus and hair-like structures called cilia. Both mucus and cilia warm and “humidify” or add moisture to the air that goes down into your lungs. This is the reason why even if it is cold outside, it does not really feel like you are breathing in cold, dry air. This is also the reason why your lungs do not freeze when it is winter. The olfactory cells, which are the nerve endings for your sense of smell, are located in the roof of the nasal cavity. For this reason, when you have a cold, you would usually be unable to smell the scent of your favorite food or your mom’s perfume.
  • Mouth: The mouth is a very important part of the respiratory system for babies. This is because they have not yet learned how to breathe through their nose. However, as a person grows older, the nose becomes the main passage of air. Usually, you use your mouth to breathe only when you are panting or gasping for air. Therefore, the mouth acts as a supplemental airway. However, the mouth is not as efficient as the nose because it lacks the vibrissae, cilia and mucous glands.
  • Pharynx. More commonly known as the nose, the pharynx serves as the airway that connects the nasal cavity and the oral cavity with the larynx and the esophagus. It is, therefore, an important part of both the respiratory and digestive systems.
  • Epiglottis: The epiglottis is a tissue that shuts off the larynx when you swallow. When it is positioned downward, you are able to swallow. When this tissue is positioned upward, air moves into your trachea. When your epiglottis is not functioning well, you could get pneumonia. This is because the lungs are normally sterile or germ-free organs and when something foreign gets in, an infection occurs, which could eventually result in pneumonia.
  • Larynx: The larynx or voicebox is responsible for voice generation. It has two pairs of vocal cords—a false pair and a true pair. As you breathe, air is forced through the true vocal cords. When you want to make a sound, your nervous system sends signals to these vocal cords, which tighten or loosen according to the pitch you want. When you have high-pitched voice, the cords are shorter. When you have a deep voice, the cords are longer.
  • Trachea: Also called the windpipe, the trachea is composed of cartilage rings. You can feel these rings when you run your palm over the front of your neck. It branches into two airways called bronchi.
  • Bronchi: You have two bronchi. One bronchus goes to your right lung and the other goes to your left lung. Both bronchi are lined with cilia and mucous glands, which also help prevent infection. When you have a lower respiratory tract infection, your bronchi produce a lot of mucus. The bacteria stick to the mucus and you expel them through coughing. Bronchi give rise to the smaller bronchioles, which are located within the lungs.
  • Lungs: The lungs are at the end of the respiratory tree. They are lobed elastic organs that expand when air goes in and contract when air goes out. Their main function is to facilitate gas exchange. Deoxygenated blood (blood without oxygen) from your organs goes to the lungs for removal of carbon dioxide and for absorption of oxygen. Because of the lungs, blood that enters the circulatory system for distribution to the rest of the body is clean and contains a lot of oxygen. This is made possible by small membranous sacs called “alveoli”. Think of them as very small balloons surrounded by very small blood vessels called capillaries. Alveoli increase the surface area for gas exchange. Just imagine, if you laid down all your alveoli in a single layer, they would occupy the surface of a whole tennis court!

What are the divisions of the respiratory system?

For convenience and for medical purposes, your respiratory system can be divided into the upper respiratory tract and the lower respiratory tract. The upper respiratory tract consists of your nose, mouth, pharynx, epiglottis, and larynx (voice box). The lower respiratory tract consists of your trachea, bronchi, bronchioles and lungs. Usually, conditions that occur in the upper respiratory tract are less serious than conditions in the lower respiratory tract. For instance, when your upper respiratory tract is affected like what happens when you have a cold, you can get well by resting and drinking lots of water. However, when your lower respiratory tract is affected, such as when you have pneumonia, you might have to be hospitalized.


What are the common diseases of the respiratory system?

The common diseases of this system include colds, cough, asthma and chronic obstructive pulmonary disease (COPD). Colds and cough are usually infectious processes caused by viruses and bacteria. Asthma is a condition induced by allergens such as pollen or dust mites. When you have asthma, your bronchioles constrict in response to allergens, leading to difficulty of breathing. In COPD, the alveolar sacs are destroyed and gas exchange becomes greatly reduced. Most of the time, chronic smoking causes this condition. Aside from COPD, smoking also causes lung cancer and other cancers. Therefore, not smoking is the best way to protect your nervous system.