Respiratory System

Last Updated: July 13, 2024

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The respiratory system is one of the most vital systems in the human body, responsible for providing the body with oxygen and getting rid of carbon dioxide.

Key Takeaways

  • Definition: The respiratory system is crucial for oxygen intake and carbon dioxide removal, involving the nose, mouth, throat, windpipe, and lungs.
  • Autonomic Nervous System: Respiration is primarily controlled involuntarily by the autonomic nervous system, though it can be voluntarily regulated.
  • Anatomy: Key parts include the nose, mouth, throat (pharynx), voice box (larynx), windpipe (trachea), and lungs.
  • Breathing Zones: The conducting zone moves air, and the respiratory zone handles gas exchange in the blood.
  • Common Conditions: Chronic conditions include asthma, COPD, lung cancer, cystic fibrosis, and sleep apnea.
  • Breathwork Benefits: Breathwork can enhance relaxation, reduce stress, improve asthma symptoms, and decrease hypertension.

Respiration is primarily an involuntary process controlled by the autonomic nervous system but can also be controlled through breathwork. The respiratory system includes many structures, including the nose, mouth, throat, windpipe, and lungs.

How Does the Respiratory System Work?

The respiratory system is primarily an involuntary system, as the body’s autonomic nervous system controls it. The respiratory system allows for many processes, but it is primarily the regulator of respiration, also known as breathing.

Breathing works to exchange oxygen entering the lungs for carbon dioxide leaving the body. Breathing is mainly an involuntary process controlled by the brain and autonomic nervous system. However, there are cases where breathing is controlled voluntarily. Examples of breathing being voluntarily controlled would be singing and speech.

The respiratory system is also involved in smell. The mucus in the respiratory system helps protect the body from microbes and viruses. The respiratory system has two zones:

  • The conducting zone moves air in and out of the lungs
  • The respiratory zone exchanges oxygen and carbon dioxide in the blood

Anatomy of The Respiratory System

The respiratory system comprises multiple organs and systems, including:

  • nose
  • mouth
  • throat (pharynx)
  • voice box
  • windpipe
  • lungs


The nose allows air to enter the body. The septum is the structure that divides the inside of the nose into two nasal cavities. The nose also filters and cleans the air entering the body and removes particles and allergens.

Sticky mucus lines the two nasal cavities to catch the particles and allergens. This mucus operates to trap dust particles, bacteria, and other environmental pollutants.

There are also tiny hairs within the nasal cavity called cilia. These tiny hairs carry mucus from the nasal cavity to the back of the throat, where it is swallowed and neutralized in the stomach.

The nose is also able to warm and moisten the air. When inhaled, air flows past the nose lining, through the sinuses, and into the conchae structure. These three folds are hollow spaces that warm and moisten the air passages and help with nasal drainage.


The mouth is a part of the upper respiratory tract. The esophagus is a passageway that leads from the mouth and throat to the stomach.

While it is much more common for people to breathe through their nasal passages, mouth breathing does occur; however, it is discouraged as a primary respiration method.

Primarily mouth-breathing is discouraged because mouth-breathing can lead to sleep disorders, dental problems, and facial structure differences. Some negative symptoms of mouth breathing include dry mouth, bad breath, drool found on pillows, and malocclusion when the upper and lower teeth do not align properly.


The throat is a component of the respiratory and digestive systems. Structurally, it is a tube lined with muscle and connects the nose and mouth to the larynx (voice box) and the esophagus.

The Nasopharynx is an important division of the pharynx as it connects to the nose and allows for air passage.

Voice box

The larynx, also known as the voice box, connects the pharynx (throat) to the remainder of the respiratory system. It aids in swallowing and contains the important structure called the vocal cords. Additional functions include creating vocal sounds such as speech and breathing.


The windpipe is medically referred to as the trachea. It carries oxygen and carbon dioxide to and from the lungs and leads into the airways. When a person inhales, oxygenated air moves through the nose or mouth, down the trachea, and into the lungs.

The mucus lines the trachea to prevent debris from entering the lungs. Cilia also exist in the trachea, just like in the nose. The trachea runs parallel to the esophagus, the tube that carries food and liquids to the stomach when food can accidentally enter the trachea, which results in coughing.

Airways and air sacs

The trachea (windpipe) essentially is a long tube connecting the larynx (voice box) bronchi structures leading to the lungs. These bronchi or bronchial tubes contain many subdivisions that send oxygen from the air into the lungs.

It starts as a left and right main bronchus, which lead into lobar bronchi that pass through the lungs. These turn into segmental branches that pass through a segment of each lobe, to finally bronchioles which are the smallest segment.

Within the bronchioles, the airways constrict (close) and dilate (open) to control airflow into and out of the lungs. The bronchioles then carry outside air to the alveoli or tiny air sacs. These small air sacs are responsible for gas exchange and have tiny blood vessels surrounding them. Therefore, the bronchial tubes are at the beginning of the airways.


The lungs work as large air-filled sacs located at the body's center. It is located in the chest cavity or the thoracic region. The ribs and below protect the sides of the lungs is the diaphragm muscle. The right lung contains three lobes or sections, and the left has two. The left lung contains the cardiac notch, which creates space for the heart. The right lung is located just above the liver.

The lungs have two membranes or protective layers, one folded on itself and one on the chest cavity. These are called pleura and release a small amount of fluid that acts like a lubricant. Because of this, the lungs work to move in the chest wall smoothly, and the lungs expand.

In inhalation (breathing in), the diaphragm muscle moves downwards towards the stomach, and the rib muscles move upwards and outwards. As a result, the chest cavity becomes larger, pulling oxygen-rich air through the nose or mouth (oral cavity) and traveling down into the lungs.

In exhalation (breathing out), the diaphragm contracts in the opposite direction, and the chest wall muscles are relaxed. It then becomes smaller, and air moves and pushes out.

Common Respiratory System Conditions

There are two categories of respiratory system conditions:

  • acute
  • chronic

Chronic respiratory diseases affect the airways and other parts of the respiratory system, including the lung, for long periods. The most common chronic respiratory conditions include:

  • Asthma
  • chronic obstructive pulmonary disease (COPD)
  • lung cancer
  • cystic fibrosis
  • sleep apnea

Two of the most important risk factors for chronic respiratory diseases are tobacco smoke, personal or second-hand smoke exposure, and air quality. Those who engage in personal smoking increase their risk of developing lung cancer, chronic obstructive pulmonary disease (COPD), and asthma.


Asthma affects a large proportion of children and adults around the world. The symptoms include shortness of breath, chest tightness, and wheezing. Asthma attacks can occur after exercise, exposure to allergens, viral respiratory infections, irritant fumes, or gasses.

An inflammation of the airway wall and a narrowing of them results in the symptoms. In people with more extreme cases of Asthma, an asthma inhaler may be required. It works to relax the muscles of the airways into the lungs, making breathing easier.

Sleep Apnea

Sleep apnea is a disorder that causes breathing to pause multiple times while sleeping. These pauses last 10 to 30 seconds and can happen numerous times throughout the night.

There are three types of sleep apnea:

  • obstructive
  • central
  • mixed

Obstructive sleep apnea is the most common, resulting from blocked upper airways during sleep. The blockage often occurs because the soft tissue at the back of the throat collapses and closes during sleep.

Other things can also block the airway, such as relaxed throat muscles, a narrow airway, a large tongue, or extra fat tissue in the throat.

Sleep apnea can also cause symptoms such as:

  • daytime sleepiness
  • loud snoring
  • gasping
  • choking during sleep
  • mood changes
  • poor concentration

Lifestyle changes can be made to reduce the symptoms. However, there are also other treatments available. A continuous positive airway pressure or CPAP machine involves wearing a special mask to keep the throat open, stop snoring, and prevent breathing pauses.

COPD (Chronic Obstructive Pulmonary Disease)

Chronic obstructive pulmonary disease (COPD)  is when the airways of the lungs become inflamed and thickened. It is often referred to also as chronic bronchitis or emphysema. With COPD, the tissue where oxygen exchange occurs is affected.

The airflow of oxygen in and out of the lungs decreases. It makes it more difficult to remove carbon dioxide into the atmosphere as waste gas.

For those living with COPD, the physical challenges that come with the disease can affect their mood and emotional health. Anxiety and depression are common in this patient population, though they often are unrecognized and left untreated.

The symptom of shortness of breath can cause anxiety and trigger panic attacks. Anxiety physiologically triggers increased ventilation or faster breathing, which can exacerbate the shortness of breath.

Research demonstrates that the management of anxiety and depression can lead to an increase in the ability of patients to stick with COPD treatment, improve physical health, and reduce medical costs.

Diagnosis of Respiratory Conditions

Spirometry is the most common test for pulmonary functioning. Spirometry measures how much air can be breathed in and out of the lungs and how fast air can be blown out.

Respiratory therapists and other healthcare professionals address respiratory health by examining lung volumes and capacities. These refer to the air volume in the lungs at different respiratory cycle phases.

Air Pollution and Respiratory Disease

The World Health Organization (WHO) has identified air pollution as a significant concern for human health. Data shows that most of the global population (99%) breathes air that exceeds WHO guidelines. Low- and middle-income countries have more exposure to harmful substances like carbon dioxide.

Air pollution, whether it be indoor or outdoor, can cause health problems, especially for those who have lung diseases. Air pollution can irritate, inflame, and destroy lung tissue. It is possible to do this even at low levels.

Those at a higher risk of getting sick from air pollution are children, seniors, and people with chronic diseases.

Local air quality indexes are readily available on phone weather apps. When outdoor air pollution is high, it is best to stay indoors. High levels of atmospheric carbon dioxide can contribute to this problem.

The Basics of Breathwork For Respiratory System

Breathwork involves deep breathing from the diaphragm or the belly, which helps promote relaxation.

The science behind breathwork involves the autonomic nervous system, which is composed of two parts.

The sympathetic nervous system is the fight or flight response.

The parasympathetic nervous system is the rest and digest response. Breathwork works to counteract the sympathetic by activating the parasympathetic division. For example, it can cause bronchodilation by relaxing the bronchial tubes.

The potential benefits of breathwork have been researched extensively and are said to:


Chronic Respiratory Diseases - Canada.ca

Living with COPD | American Lung Association

COPD and Emotional Health | American Lung Association

Aorta anatomy | Clevelandclinic.org

Air pollution

National Heart, Lung, and Blood Institute (NHLBI)

Respiratory System: Respiratory Functions - LabXchange


The contents of this article are provided for informational purposes only and are not intended to substitute for professional medical advice, diagnosis, or treatment. It is always recommended to consult with a qualified healthcare provider before making any health-related changes or if you have any questions or concerns about your health. Anahana is not liable for any errors, omissions, or consequences that may occur from using the information provided.