Medical Terminology: The Respiratory System

1. What is The Respiratory System?
The respiratory system has the following basic functions:
- Movement of air in and out of the lungs
- Exchange of oxygen and carbon dioxide
- Helping maintain acid-base balance
Ventilation moves air in (inspiration) and out (expiration) of the lungs. During inspiration, air flows in through the nose and passes into the nasopharynx. Air is then drawn through the pharynx, larynx, trachea, and bronchi. The bronchi branches (bifurcates) right and left into smaller tubes called bronchioles that terminate in alveoli.
The airways are lined with mucous membranes to add moisture to the inhaled air. There is a thin layer of mucus in the airways that helps to trap foreign particles such as dust, pollen, or bacteria. Cilia—small, hairlike projections—help to move the mucus with the foreign material upward so it can be coughed out.
Alveoli are air-filled sacs containing membranes coated with surfactant. The surfactant helps the alveoli to expand evenly on inspiration and prevents collapse on exhalation. Carbon dioxide and oxygen are exchanged; a higher concentration of gas moves to the lower area of concentration. A higher concentration of carbon dioxide in the hemoglobin moves across the membranes into the alveoli and is expired by the lungs. The higher concentration of oxygen in the alveoli crosses the membrane and attaches to the hemoglobin, which is then distributed by the circulatory system throughout the body.
Lungs are contained within a pleural sac in the thoracic cavity and operate on negative pressure. The visceral pleura is close to the lungs and the parietal pleura is close to the chest wall. There is a pleural space between these two layers that contains a small amount of fluid to prevent friction with chest movement on inspiration and expiration.

2. Acute Respiratory Distress Syndrome (ARDS)
Patients develop acute respiratory failure. Lungs stiffen as a result of a buildup of fluid in the lungs. Fluid builds up in the tissue of the lungs (interstitium) and the alveoli. This fluid and stiffness impairs the lungs’ ability to move air in and out (ventilation). There is an inflammatory response in the tissues of the lungs.
Damage to the surfactant within the alveoli leads to alveolar collapse, further impairing gas exchange. An attempt to repair the alveolar damage may lead to fibrosis within the lung. Even as the respiratory rate increases, sufficient oxygen cannot get into the circulation (hypoxemia).
Oxygen saturation decreases. Respiratory acidosis develops, and the patient appears to have respiratory distress. This is most commonly caused by shock, sepsis, or as a result of trauma or inhalation injury. Patients may have no history of pulmonary disorders, also known as adult respiratory distress syndrome.

3. Asbestosis
Asbestos fibers enter the lungs, causing inflammation in the bronchioles and the walls of the alveoli. After inhalation, the fibers settle into the lung tissue. Fibrosis develops and ultimately pleural plaques form. The changes within the lung result in a restrictive lung disease. The damage to the lung causes impairment in breathing and air exchange.

4. Asthma
The airways become obstructed from either inflammation of the lining of the airways or constriction of the bronchial smooth muscles (bronchospasm). A known allergen (for example, pollen) is inhaled, causing activation of antibodies that recognize the allergen. Mast cells and histamine are activated, initiating a local inflammatory response. Prostaglandins enhance the effect of histamine.
Leukotrienes also respond, enhancing the inflammatory response. White blood cells responding to the area release inflammatory mediators. A stimulus causes an inflammatory reaction, increasing the size of the bronchial linings; this results in restriction of the airways. There may be a bronchial smooth muscle reaction at the same time.
There are two kinds of asthma:
- Extrinsic: Also known as atopic, caused by allergens such as pollen, animal dander, mold, or dust. Often accompanied by allergic rhinitis and eczema; this may run in families.
- Intrinsic: Also known as nonatopic, caused by a nonallergic factor such as following a respiratory tract infection, exposure to cold air, changes in air humidity, or respiratory irritants.

5. Atelectasis
A portion of the lung does not expand completely, decreasing the lung’s capacity to exchange gases and resulting in decreased oxygenation of blood. Obstruction of part of the airway causes collapse distal to the area that is blocked. Obstruction can be from a mucous plug inside the airway, or a tumor or fluid within the pleural space that may be pressing on the airway from the outside. Postoperatively, patients are at risk for atelectasis because of pain, immobility, medications for pain, anesthesia, and lack of deep breathing.

6. Bronchiectasis
Bronchi and bronchioles become abnormally and permanently dilated because of infection and inflammation. This results in excessive production of mucus that obstructs the bronchi. There is some obstruction of the airways and a chronic infection. The changes within the lung can be localized or generalized. The lung may develop areas of atelectasis where thick mucus obstructs the smaller airways, making the mucus difficult to expel. This results in inflammation and infection of the airways and leads to bronchitis.

7. Bronchitis
Increased mucus production, caused by infection and airborne irritants that block airways in the lungs, results in the decreased ability to exchange gases. There are two forms of bronchitis: acute, in which blockage of the airways is reversible; and chronic, in which blockage is not reversible.
Patients with acute bronchitis are symptomatic typically for 7. to 10. days, often because of viral (but sometimes bacterial) infection. Patients with chronic bronchitis have symptoms of a chronic productive cough for at least 3. consecutive months and up to 2. consecutive years. There is increased mucus production, inflammatory changes, and, ultimately, fibrosis in the airway walls. The patient with chronic bronchitis has an increased incidence of respiratory infection.

8. Cor Pulmonale
In cor pulmonale, the structure and function of the right ventricle are compromised by chronic obstructive pulmonary disease (COPD), obstruction of the airflow into and out of the lungs. The heart tries to compensate, resulting in right-sided heart failure. The patient has heart failure because of a primary lung disorder that causes pulmonary hypertension and enlargement of the right ventricle. Patients have symptoms of both the underlying pulmonary disorder and the right-sided heart failure. COPD consists of chronic bronchitis and emphysema.

9. Emphysema
Chronic inflammation reduces the flexibility of the walls of the alveoli, resulting in overdistention of the alveolar walls. This causes air to be trapped in the lungs, impeding gas exchange. Smoking is often linked to development of emphysema. A less frequent cause is an inherited alpha1-antitryptan deficiency.

10. Lung Cancer
Lung cancer is abnormal, uncontrolled cell growth in lung tissues, resulting in a tumor. A tumor in the lung may be primary when it develops in lung tissue. It may be secondary when it spreads (metastasizes) from cancer in other areas of the body such as the liver, brain, or kidneys.
There are two major categories of lung cancer: small cell and non-small cell. Repetitive exposure to inhaled irritants increases a person’s risk for lung cancer. Cigarette smoke, occupational exposures, air pollution containing benzopyrenes, and hydrocarbons have all been shown to increase risk.
- Small Cell:
Oat Cell: Fast-growing, early metastasis
- Non-Small Cell:
Adenocarcinoma: Moderate growth rate, early metastasis
Squamous Cell: Slow-growing, late metastasis
Large Cell: Fast-growing, early metastasis

11. Pleural Effusion
Pleural effusion is the abnormal accumulation of fluid within the pleural space between the parietal and visceral pleura covering the lungs. The fluid may be serous fluid, blood (hemothorax), or pus (empyema). Fluid builds up when the development of the fluid exceeds the body’s ability to remove the fluid. Excess fluid inhibits full expansion of the lung.
A large area of fluid buildup will displace the lung tissue, compromising air exchange in the area. As fluid builds up and takes the place of lung tissue, it may push the collapsing lung past the middle (mediastinum) of the chest. This displaces the central structures, compromising the air exchange of the other lung as well.
Causes of pleural effusion are varied and include congestive heart failure, renal failure, malignancy, lupus erythematosus, pulmonary infarction, infection, or trauma. It can also occur as a postoperative complication.

12. Pneumonia
Infectious pneumonia may result from a variety of microorganisms and can be community acquired or hospital acquired (nosocomial). A patient can inhale bacteria, viruses, parasites, or irritating agents, or aspirate liquids or foods. He or she can also develop increased mucus production and thickening alveolar fluid as a result of impaired gas exchange. All of these can lead to inflammation of the lower airways.
Organisms commonly associated with infection include Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenza, Mycoplasma pneumoniae, Legionella pneumonia, Chlamydia pneumoniae (parasite), and Pseudomonas aeruginosa.

13. Pneumothorax
The pleural sac surrounding the lung normally contains a small amount of fluid to prevent friction as the lungs expand and relax during the respiratory cycle. When air is allowed to enter the pleural space between the lung and the chest wall, a pneumothorax develops. This air pocket takes up space that is normally occupied by lung tissue, causing an area of the lung to partially collapse.
If there is a penetrating chest wound, the patient may have an open pneumothorax, also known as a sucking chest wound (for the sound it makes during breathing).
A closed pneumothorax may be caused by blunt trauma, postcentral line insertion, or postthoracentesis. Spontaneous pneumothorax may be secondary to another disease or occur on its own. As the air accumulates, there may be a partial or complete collapse of the lung—the more air that accumulates, the greater the area of collapse.
If there is a large enough amount of air trapped between the pleural layers, the tension within the area increases. This increase in tension results in pushing the mediastinum toward the unaffected lung, causing it to partially collapse and compromising venous return to the heart. This is a tension pneumothorax.

14. Respiratory Acidosis
Hypoventilation, asphyxia, or central nervous system disorders cause a disturbance in the acid-base balance of the patient’s blood, resulting in increased carbon dioxide in the blood (hypercapnia). The increase in carbon dioxide in the blood combines with water; this combination releases hydrogen and bicarbonate ions.
The brainstem is stimulated and increases the respiratory drive to blow off carbon dioxide. Over time, the sustained elevated arterial carbon dioxide level causes the kidneys to attempt to compensate by retaining bicarbonate and sodium and excreting hydrogen ions.

15. Tuberculosis (TB)
Tuberculosis (TB) is an infectious disease spread by airborne route. Infection is caused by inhalation of droplets that contain the tuberculosis bacteria (Mycobacterium tuberculosis).
An infected person can spread the small airborne particles through coughing, sneezing, or talking. Close contact with those affected increases the chances of transmission. Once inhaled, the organism typically settles into the lung, but can infect any organ in the body. The organism has an outer capsule. Primary TB occurs when the patient is initially infected with the mycobacteria. After being inhaled into the lung, the organism causes a localized reaction.
As the macrophages and sensitized T lymphocytes attempt to isolate and kill off the mycobacterium within the lung, damage is also caused to the surrounding lung tissue. A well-defined granulomatous lesion develops that contains the mycobacterium, macrophages, and other cells. Necrotic changes occur within this lesion. Gaseous granulomas develop along lymph node channels during the same time.
These areas create a Ghon’s complex, which is a combination of the area initially infected by the airborne bacillus (called the Ghon’s focus) and a lymphatic lesion. The majority of people with newly acquired infections and an adequate immune system develop latent infection, as the body walls off the infecting organism within these granulomas. Disease is not active in these patients at this point and will not be transmitted until there is some manifestation of the disease. In patients with inadequate immune response, the TB is progressive, lung tissue destruction continues, and other areas of the lung also become involved. In secondary TB, the disease is reactivated at a later stage.
The patient may be reinfected from droplets or from a prior primary lesion. Since the patient has previously been infected with TB, the immune response is to rapidly wall off the infection. Cavitation of these areas occurs as the organism travels along the airways. Exposure to TB occurs when a person has had recent contact with a person suspected or confirmed of having TB. These patients do not have a positive skin test, signs or symptoms of disease, or chest X-ray changes. They may or may not have disease.
Latent TB infection occurs when a person has a positive tuberculin skin test but no symptoms of disease. Chest X-ray may show granuloma or calcification. TB disease is confirmed when a person has signs and symptoms of TB. The chest X-ray typically has abnormalities in the apical aspects of the lung fields. In HIV patients, other areas may also be affected.

16. Acute Respiratory Failure
The lungs are unable to adequately exchange oxygen and carbon dioxide because of insufficient ventilation. The body is not able to maintain enough oxygen or the body may not get rid of enough carbon dioxide. A respiratory illness can deteriorate into acute respiratory failure. Central nervous system depression (because of trauma or medication) or disease can also lead to acute respiratory failure.

17. Pulmonary Embolism
Blood flow is obstructed in the lungs caused by a thrombus (blood clot), air, or fat emboli that become stuck in an artery, causing impaired gas exchange. Patients may be predisposed to clot formation, have pooling of blood, or damage to vessel walls, or take certain medications that increase the risk of a thrombus formation. A thrombus is commonly found in vessels in lower extremities.
When a thrombus loosens and travels in the peripheral circulation, it is called an embolus. The embolus travels through the right side of the heart and is sent to the lungs where it lodges in one of the arteries. Depending on the size of the artery that the embolus lodges in, a section of lung will have no blood supply and alveolar function will suffer. As blood supply to an area of the lung diminishes, alveoli collapse, causing atelectasis.

18. Influenza
Influenza is a viral infection affecting the respiratory tract that spreads through droplets. The virus can be inhaled or picked up from surfaces through direct contact. Infection can settle into either the upper or lower respiratory tract. The virus causes damage to the upper layers of cells. The natural defenses of the respiratory tract are compromised and it is easier for bacteria to attach to the underlying respiratory tissues.

19. Bronchoscopy
Bronchoscopy is used to view the bronchial tree and remove foreign obstructions, obtain tissues for biopsy, or for suctioning fluid. The patient is anesthetized and a bronchoscope is inserted into the patient’s mouth and down the trachea and bronchial tree. The bronchoscope contains a tiny video camera and probe that the health care provider manipulates to perform the procedure.

20. Pulmonary Angiography
Pulmonary angiography provides a view of the pulmonary circulatory system so that the health care provider can determine the condition of blood flow to the lungs. Radiopaque dye is inserted into the patient’s veins after a catheter has been passed through the heart into the pulmonary artery fluoroscopically. The image is watched on a screen as the dye flows through the pulmonary circulatory system.

21. Sputum Culture and Sensitivity
Sputum from the patient is cultured to determine which, if any, bacterium is contained in the sputum and determine which antibiotic kills the bacterium. Sputum is collected from the patient in a sterile container and sent to the laboratory, where the sample is smeared in petri dishes and incubated to grow the bacterium. Samples of the bacteria are stained and examined under a microscope to identify the bacterium. The samples are checked periodically, but are usually given 72. hours to complete the testing process. Once identified, bacterium are exposed to known antibiotics to determine which antibiotic kills the bacterium.

22. Thoracentesis
Thoracentesis is the removal of fluid from the pleural sac to drain fluid or identify the contents of the fluid. The patient either sits at the edge of the bed or lies on the unaffected side. The affected site is anesthetized. A needle is inserted into the plural sac and fluid is drained using a syringe.

Basic Questions
Respiratory System

1. What is acute respiratory distress syndrome (ARDS)?
Patients develop acute respiratory failure. Lungs stiffen as a result of a buildup of fluid in the lungs. Fluid builds up in the tissue of the lungs (interstitium) and the alveoli. This fluid and stiffness impairs the lungs’ ability to move air in and out (ventilation). There is an inflammatory response in the tissues of the lungs.

2. What causes further impairment to gas exchanges in a patient who has ARDS?
Damage to the surfactant within the alveoli leads to alveolar collapse, further impairing gas exchange.

3. What are common causes of ARDS?
This is most commonly caused by shock, sepsis, or as a result of trauma or inhalation injury. Patients may have no history of pulmonary disorders.

4. What is asbestosis?
Asbestos fibers enter the lungs, causing inflammation in the bronchioles and the walls of the alveoli. After inhalation, the fibers settle into the lung tissue. Fibrosis develops and ultimately pleural plaques form.

5. What is asthma?
The airways become obstructed from either inflammation of the lining of the airways or constriction of the bronchial smooth muscles (bronchospasm).

6. What is extrinsic asthma?
Extrinsic asthma, also known as atopic, is caused by allergens such as pollen, animal dander, mold, or dust. It is often accompanied by allergic rhinitis and eczema; this may run in families.

7. What is intrinsic asthma?
Intrinsic asthma, also known as nonatopic, is caused by a nonallergic factor such as following a respiratory tract infection, exposure to cold air, changes in air humidity, or respiratory irritants.

8. What is atelectasis?
A portion of the lung does not expand completely, decreasing the lung’s capacity to exchange gases, which results in decreased oxygenation of blood.

9. What are common causes of atelectasis?
Obstruction can be from a mucous plug inside the airway, or a tumor or fluid within the pleural space may be pressing on the airway from the outside. Postoperatively, patients are at risk for atelectasis because of pain, immobility, medications for pain, anesthesia, and lack of deep breathing.

10. What is bronchiectasis?
Bronchi and bronchioles become abnormally and permanently dilated, caused by infection and inflammation. This results in excessive production of mucus that obstructs the bronchi. There is some obstruction of the airways and a chronic infection.

11. What is bronchitis?
Increased mucus production, caused by infection and airborne irritants that block airways in the lungs, results in the decreased ability to exchange gases.

12. What is the difference between acute and chronic bronchitis?
There are two forms of bronchitis: acute bronchitis, in which blockage of the airways is reversible; and chronic bronchitis, in which blockage is not reversible.

13. What is cor pulmonale?
In cor pulmonale, the structure and function of the right ventricle are compromised by chronic obstructive pulmonary disease (COPD), obstruction of the airflow into and out of the lungs. The heart tries to compensate, resulting in right-sided heart failure.

14. What is the cause of heart failure in cor pulmonale?
The patient has heart failure caused by a primary lung disorder, which causes pulmonary hypertension and enlargement of the right ventricle.

15. What symptoms are expected in cor pulmonale?
Patients have symptoms of both the underlying pulmonary disorder and the right-sided heart failure.

16. What is chronic obstructive pulmonary disease (COPD)?
COPD consists of chronic bronchitis and emphysema.

17. What is emphysema?
Chronic inflammation reduces the flexibility of the walls of the alveoli, resulting in overdistention of the alveolar walls. This causes air to be trapped in the lungs, impeding gas exchange.

18. What is a common cause of emphysema?
A common cause of emphysema is smoking.

19. What are the two major categories of lung cancer?
Two major categories of lung cancer are small cell and non-small cell.

20. What subcategory of lung cancer grows slowly?
Squamous cell is the subcategory of lung cancer that grows slowly.

21. What is pleural effusion?
Pleural effusion is abnormal accumulation of fluid within the pleural space between the parietal and visceral pleura covering the lungs.

22. What is a result of pleural effusion?
A large area of fluid buildup displaces the lung tissue, compromising air exchange in the area. As fluid builds up and takes the place of lung tissue, it may push the collapsing lung past the middle (mediastinum) of the chest. This displaces the central structures, compromising the air exchange of the other lung as well.

23. What are causes of pleural effusion?
Causes of pleural effusion are varied and include congestive heart failure, renal failure, malignancy, lupus erythematosus, pulmonary infarction, infection, or trauma. It can also occur as a postoperative complication.

24. What is pneumonia?
Infectious pneumonia may result from a variety of microorganisms and can be community acquired or hospital acquired (nosocomial). A patient can inhale bacteria, viruses, parasites, or irritating agents, or aspirate liquids or foods. He or she can also develop increased mucus production and thickening alveolar fluid as a result of impaired gas exchange. All of these can lead to inflammation of the lower airways.

25. What is a pneumothorax?
The pleural sac surrounding the lung normally contains a small amount of fluid to prevent friction as the lungs expand and relax during the respiratory cycle. When air is allowed to enter the pleural space between the lung and the chest wall, a pneumothorax develops