The Respiratory System & Related Disorders

The Respiratory System

The respiratory system is the group of organs that are involved in the process of breathing. The parts of your body that comprise this system are the nose, mouth, diaphragm, throat, lungs and airways. Our respiratory system regulates the exchange of air in our lungs from oxygen to carbon dioxide.

respiratory system diagram

Oxygen is a vital necessity for every cell in our body. The body inhales oxygen by contracting the diaphragm and pumps that oxygen-rich air into the lungs. Inside the lungs are small air sacs called alveoli. The alveoli move the oxygen into the bloodstream where it is pumped to the rest of the the body by the heart. Through this process, the alveoli also exchange the oxygen they are carrying for carbon dioxide, which is then carried through the bloodstream and exhaled from the body as waste.

gas exchange in lungs

The process of breathing begins by the contraction of the diaphragm, which pulls air in through the nose and mouth. That air then flows down through the trachea and air passages called bronchial tubes. As the bronchial tubes pass through the lungs, they divide into smaller air passages called bronchioles. At the end of the bronchioles, there are small air sacs called alveoli. The average person has over 300 million alveoli.  Tiny blood vessels called capillaries surround the alveoli. Oxygen from the inhaled air passes through the alveoli walls and into the blood, where it is then carried to the heart. 

The heart pumps the oxygenated blood to the rest of the body so the cells, tissues, and organs can function. Carbon dioxide is produced as the oxygen in the blood is used up. The blood then carries this carbon dioxide-rich blood back to the lungs, where it goes into the capillaries and is exhaled out of the body. 

Disorders of the Respiratory System

Pulmonary or respiratory medicine is a specialty dedicated to the diagnosis and treatment of breathing disorders and the lungs.

Below is a list of a few of the most common diseases that affect the respiratory system and some of the treatments doctors can use to treat them.


Asthma is a condition in which the airways leading to the lungs swell with inflammation and mucous. This can make breathing extremely difficult and, in some cases, can be life threatening. Asthma affects more than 15 million people, resulting in about 5,000 deaths yearly.


Symptoms of asthma may include

  • Difficulty breathing or shortness of breath 
  • Pressure, tightness, or pain in the chest 
  • Wheezing, coughing, whistling, or shortness of breath when exhaling
  • Wheezing or coughing fits caused by strenuous activity 

Asthma can worsen over time, which can lead to increased severity of symptoms. Asthma attacks can be life-threatening in some severe cases. 

Asthma can flare up in certain situations such as when exercising, when at work in a physically demanding job or occupation with particles in the air, or when certain allergens are present. Air quality and temperature, as well as presence of certain chemicals, can also cause or worsen symptoms.

Diagnosis & Treatment

There is no way to cure asthma, but diagnosis and treatment is readily available by medical professionals who are specially trained in pulmonary medicine. Pulmonary specialists can properly diagnose, treat, and manage asthma so that it does not impact quality of life.  

Some of these treatment plans can include:

  • Special medicines are available to reduce and mitigate symptoms. Regular testing is advised to monitor the condition.  
  • Preventing illnesses that can aggravate symptoms by staying up to date with all vaccinations. 
  • Identification and avoidance of asthma triggers. A number of outdoor allergens and irritants including pollen, mold, cold air, and air pollution can trigger asthma attacks.


Pneumonia is a lung infection that can have many causes, and can range from mild to very severe. It can be caused by a virus or a bacteria.

Pneumonia causes the alveoli in the lungs to fill with fluid or pus.Young children and older adults are at a higher risk for infection, though anyone can get pneumonia, and the severity can range from mild to life-threatening. Even with treatment, pneumonia can still cause severe and sometimes deadly complications such as:

  • Bacteria in the bloodstream, which can cause infections of other organs and lead to organ failure. 
  • Difficulty breathing, especially in those with preexisting conditions or individuals who smoke, which may necessitate hospitalization and need for a breathing machine (ventilator). 
  • Buildup of fluid or abscesses in the thin space between layers of tissue that line the lungs and chest. There is a possibility that this fluid can become infected and will need to be drained through a chest tube or via surgery. Abscesses can be drained in the same way or treated with antibiotics.


Symptoms of pneumonia can vary depending on the age of the person infected, their lifestyle, and the type of infection (whether it is viral or bacterial). 

Signs and symptoms of pneumonia may include:

  • Chest pain while breathing or coughing
  • Cough, which may produce phlegm
  • Fatigue
  • Fever, sweating and shaking chills
  • Lower than normal body temperature (in adults older than age 65 and people with weak immune systems)
  • Nausea, vomiting or diarrhea
  • Shortness of breath
  • Confusion or changes in mental awareness (in adults age 65 and older)

You should see your doctor if you have difficulty breathing, chest pain, persistent fever of 102 F (39 C) or higher, or persistent cough, especially if you’re coughing up pus.

Diagnosis & Treatment

Pneumonia can be diagnosed by a medical professional using a number of methods, some of which are listed below:

  • Blood tests evaluate the blood taken for evidence of an infection, which can be either viral or bacterial. 
  • Chest X-rays give your doctor an idea of where the infection is in your lungs, however it does not indicate the kind of infection. 
  • Pulse oximetry measures the oxygen level in your blood, which is negatively affected by the pneumonia in your lungs. 
  • A sample of fluid from your lungs (sputum) is taken after a deep cough and analyzed to help pinpoint the cause of the infection.

Pneumonia can be treated a number of ways, but the cause, age, and lifestyle of the patient will determine the exact treatment needed.

  • Antibiotics are used to treat pneumonia caused by a bacterial infection. The testing methods above are most often used to determine the type of infection.
  • Cough medicine may be used to calm the cough so the patient can rest. 
  • Fever reducers and pain relievers are used to relieve symptoms associated with viral pneumonia, which cannot be cured with most medications and must be dealt with by our body’s immune system.

Chronic Obstructive Pulmonary Disease (COPD)

Chronic Obstructive Pulmonary Disease (COPD) is a group of lung diseases that cause restricted airflow in the lungs and result in difficulty breathing. 16 million people in America are affected by COPD, but it is estimated millions more are undiagnosed. 

COPD is caused by long-term exposure to irritating gases or particulate matter. Tobacco smoke is the most common irritant and smokers are at a very high risk for developing COPD. People with COPD are at increased risk of developing other serious conditions such as heart disease and lung cancer. 

Some of the main diseases associated with COPD are:

  • Chronic bronchitis – an inflammation of the bronchial tubes that carry air to the lungs. 
  • Emphysema – damage to the alveoli that deliver oxygen from the air into our blood. 
  • Refractory, or non-reversable, asthma, which does not respond to conventional asthma medications. 
  • Sleep apnea and other breathing disorders that occur during sleep.

COPD can lead to many other complications.

  • Those with COPD are more likely to get respiratory infections such as colds, the flu, and pneumonia.
  • COPD can increase the risk of heart disease, including heart attack. 
  • People with COPD are more likely to develop lung cancer. 
  • COPD may cause a rise in blood pressure in the arteries that bring blood to your lungs. 
  • Difficulty breathing and a chronic illness can lead to depression and depression-like symptoms.


COPD might not show itself right away, but over time the symptoms and signs of COPD can get worse and even become severe and deadly. If you are experiencing any of the below, you should see a pulmonary specialist about testing:

  • A cough that doesn’t go away
  • Coughing up lots of mucus
  • Shortness of breath, especially when you’re physically active
  • Wheezing or squeaking when you breathe
  • Tightness in the chest
  • Frequent colds or flu
  • Blue fingernails
  • Low energy
  • Losing weight without trying (in later stages)
  • Swollen ankles, feet, or legs


COPD might not show itself right away, but over time the symptoms and signs of COPD can get worse and even become severe and deadly. If you are experiencing any of the below, you should see a pulmonary specialist about testing:

  • A cough that doesn’t go away
  • Coughing up lots of mucus
  • Shortness of breath, especially when you’re physically active
  • Wheezing or squeaking when you breathe
  • Tightness in the chest
  • Frequent colds or flu
  • Blue fingernails
  • Low energy
  • Losing weight without trying (in later stages)
  • Swollen ankles, feet, or legs

Diagnosis & Treatment 

Your doctor may decide to conduct a number of tests to diagnose COPD, including:

  • Spirometry, which is a test that measures how much air your lungs can hold and how fast you can blow air out of them.
  • Chest X-rays 
  • CT scans
  • Tests that measure how well your lungs bring in oxygen, known as arterial blood gas tests

Unfortunately, there is no cure for COPD, so the goal is to treat the symptoms of the disease. One of the best things you can do is to stop smoking if you are a smoker or lessen your exposure to harmful toxins in the air. 

Breathing Disorders During Sleep

Sleep disorders that involve difficulty breathing during sleep are classified as sleep related breathing disorders. 20 million people (children and adults) are affected by breathing disorders during sleep.

Most of these are characterized by abnormal breathing during sleep. This could be partial obstruction of the airway without sleep disturbance (snoring) or different kinds of apnea, which is a halting of breathing. 

Disorders such as these expose patients to cardiovascular disease (heart attack, cardiac arrhythmia, and heart failure, for example), high blood pressure, strokes, depression, car accidents, and poor performance in school or at work.

The dangers of sleep breathing disorders should not be underestimated. The complications that can arise from certain breathing sleep disorders can be severe and life-threatening.

Sleep apnea is a serious medical condition. Complications can include:

  • High blood pressure or heart problems including recurrent heart attacks or stroke
  • Type 2 diabetes
  • Metabolic syndrome, which includes diabetes, abnormal cholesterol levels and high blood sugar
  • Complications with medications and surgery
  • Liver disease

If you suspect you have sleep apnea, you should consult with a medical professional specially trained in sleep medicine.

For more information on sleep apnea or other sleep disorders please click here


While not a disease in itself, diseases caused by smoking kill more than 480,000 people in the U.S. each year. Smoking causes almost 90% of deaths from lung cancer. It also causes almost 90% of deaths from Chronic Obstructive Pulmonary Disease (COPD). Smokers are 12 to 13 times more likely to die from COPD than non-smokers. Besides COPD and emphysema, smokers are at very high risk for lung and other kinds of cancer. If you have asthma, tobacco smoke can trigger an attack or make an attack worse.

According to the CDC, smoking causes more deaths each year than the following causes combined:

  • Human immunodeficiency virus (HIV)
  • Illegal drug use
  • Alcohol use
  • Motor vehicle injuries
  • Firearm-related incidents