Respiratory System

Respiratory system definition

The respiratory system is comprised of the parts of your body that make respiration or breathing, possible. The primary organ involved in your respiratory system is your lungs. Your lungs are responsible for taking in oxygen and expelling carbon dioxide, the waste product of cellular respiration. Your lungs are able to contract and expand due to their elasticity. The lungs are located within your rib cage in an area known as the thorax. Another portion of your body that allows your lungs to contract and expand is your diaphragm.

Respiratory system diagram

Below in Figure 1, you can see a complete diagram of the respiratory system. Try to visualize the path that air travels as it is inhaled by your nose. This will help you to better understand how your respiratory system works to keep your body oxygenated.

In the next section, we will be discussing the respiratory system's function in more detail, as well as the possible diseases that can interrupt its normal functioning.

Respiratory system organs

There are many different parts of the respiratory system and each play an important role in providing your body with oxygen. Each part of the respiratory system has many different components, each with specialized functions. As you breathe in oxygen from the atmosphere, your airways deliver that air to your lungs, where a series of reactions take place to transfer the oxygen into your bloodstream. Your airways are comprised of multiple different components, including:

• Nose, mouth, and tonsils: Your nose and mouth pull air from the environment into your body, while your tonsils filter harmful particles from the air.

• Cilia: Small hairs that filter out particles such as dust and mold from the air you breathe.

• Sinuses: These are hollow areas in your nose, skull, and throat that help to filter out particles and also warm the air you breathe so that your lungs are not shocked by air that is too hot or too cold.

• Pharynx (throat): This is a tube that delivers air from your nose into your trachea.

• Trachea: The tube-like structure that carries air from your pharynx to your lungs for processing.

• Bronchial Tubes: These are tubes that branch off of the trachea and connect to each lung. These tubes make sure that the air gets deposited into the lungs.

• Lungs: The organs that remove oxygen from the air you breathe and transport it into your bloodstream.

• Alveoli: These are tiny air sacs located in the lungs where the exchange of carbon dioxide takes place.

• Bronchioles: These are small branches of bronchial tubes that span the entire lung and lead air to the alveoli.

• Capillaries: Small blood vessels within the alveoli that move oxygen into the bloodstream while moving carbon dioxide out of the bloodstream.

Your respiratory system also includes muscles and bones to help move the air you breathe into your lungs while also helping the air you exhale leave your body. These structures include:

• Diaphram: The aforementioned large muscle located below your lungs that helps expand and constrict your lungs so that they can pull in and release air.

• Ribs: Bones that surround and protect your lungs from damage.

Respiratory system function

Your respiratory system brings in oxygen from the atmosphere into your bloodstream for your body to use. Oxygen is the primary source that keeps your body alive. Your cells use oxygen to generate energy in order for your cells to continue working in harmony. Your lungs are organs in charge of regulating your oxygen intake. They do this by expanding and contracting to either bring in oxygen or release carbon dioxide from your body. Your lung's ability to take in or release oxygen is based on partial pressure.

Gas exchange in your respiratory system occurs mainly via diffusion. This means that gas molecules travel from an area of high concentration to an area of low concentration. If your capillaries have a low oxygen concentration, but a high carbon dioxide concentration, your blood will exchange carbon dioxide for oxygen in the lungs so that your blood can acquire the oxygen it needs. The air in our lungs has a higher oxygen concentration than deoxygenated blood which is why oxygen readily flows from the lungs to the bloodstream.

Similarly, the lungs have a lower concentration of carbon dioxide compared to deoxygenated blood which is why carbon dioxide flows from the bloodstream into the lungs for exhalation. The concentration gradient between the blood and the lungs allows for the exchange of these gases which is an important process for maintaining homeostasis.

The concentration gradient between the lungs and the environment is also very important. Since the environment has a higher concentration of oxygen compared to inside the body, oxygen can readily flow into our lungs from the air we breathe. Likewise, since the concentration of carbon dioxide is lower in the atmosphere compared to our lungs, the carbon dioxide produced by our bodies can readily flow from our lungs and into the environment.

Now, let's discuss the path air takes to get to the lungs. As you breathe in air from the environment, it flows through your nose and gets filtered and warmed by your sinuses and the cilia in your nose. After filtration, the air then moves through your throat and gets further filtered by your tonsils, and then moves to your trachea. As air travels down your trachea, it flows through a series of branches, where the trachea branches off into different components similar to how roads branch off of a highway. The first branch point creates the bronchial tubes that connect to each lung. Once the bronchial tubes reach the lungs, they further branch into the bronchioles, which will lead the air into the alveoli. Once the air reaches the alveoli, gas exchange takes place. Once carbon dioxide enters the alveoli, it travels up the bronchioles into the bronchial tubes and into the trachea. Once in the trachea, the carbon dioxide then travels through the throat and finally out of the nose and into the environment. See Figure 2.

Respiratory system diseases

In the previous sections, we discussed the organs associated with the respiratory system, as well as how the system functions to bring in oxygen to the body. In this section, we will discuss how respiratory diseases, such as COVID-19, can disrupt respiratory system function. There are many respiratory diseases worldwide, most of which are viral or allergy based. Microbes, such as dust, mold, bacteria, and viruses, can enter the respiratory system through the air that we breathe. There are many different allergens in the world and if your body is allergic to any of these, your immune system will overreact, causing swelling of your sinuses and an overproduction of mucus to flush the allergens out of your respiratory system.

Unlike allergens, respiratory diseases like viruses infect healthy cells in the respiratory system. Some respiratory viruses include influenza and COVID-19. These viruses infect cells of the respiratory cells and can cause poor oxygen diffusion into the bloodstream which deprives your body of needed oxygen. Influenza enters your body through receptors located in your nasal passage while COVID-19 enters your body through receptors found all throughout your body. Once in your cells, influenza and COVID-19 viruses hijack the cell in order to replicate themselves. As the virus uses the host cell to replicate over and over again, the host cell becomes weak and eventually dies. If many of your lung cells die then your lung will no longer be able to function and your body will not get the oxygen it needs. Typically, your immune system is good at killing respiratory viruses in time so that your lungs do not get damaged; however, if you have a respiratory virus, it is important to rest and hydrate to give your body a chance to fight the virus.