Disorders of The Respiratory System

Inflammatory Disorders

Chronic obstructive pulmonary disease (COPD) is a group of disorders in which there is a long-term obstruction that reduces airflow to and from the lungs. The two most important COPDs are chronic bronchitis and emphysema.

Bronchitis is inflammation of the bronchi, and it is characterized by excessive mucus production that partially obstructs air flow. Acute bronchitis is usually caused by viral or bacterial infections. Chronic bronchitis occurs in chronic asthmatics, and it is common in smokers due to persistent exposure to irritants in tobacco smoke.

Emphysema results from long-term exposure to airborne irritants, especially tobacco smoke. It is characterized by a rupture of the alveoli, forming larger spaces in the lungs, and excess mucus production, which plugs terminal bronchioles, trapping air in the alveoli.    These changes reduce the respiratory surface area and impairs gas exchange.

Exhaling requires voluntary effort by the patient. The disease is uncommon except among long-term smokers, and people with long-term exposure to second hand smoke. It usually can be prevented and progressive deterioration can be stopped by removing the airborne irritant- usually tobacco smoke. Otherwise, there is no cure.

Asthma (az’-mah) is another COPD but differs in that reduction in airflow is usually intermittent rather than constant. It is characterized by wheezing upon exhilation and dyspnea (labored breathing) that result from bronchoconstriction. It is often caused by an allergic reaction to airborne substances but also may result from hypersensitivity to bacteria or viruses infecting the bronchial tree.

The common cold is an infection of the upper respiratory tract. It may be caused by a number of viruses, and often involves rhinitis, laryngitis, and sinusitis. Excessive mucus production, sneezing, and congestion are common symptoms.

Rhinitis (ri-ni ‘-tis), laryngitis, and sinusitis are the inflammation of the mucosae lining the nasal cavity, the larynx, and the sinuses, respectively. They are characterized by an increased mucus secretion. Causes may be viral or bacterial infections or airborne allergens.

Influenza, or flu, is an infectious disease that may involve both the upper and the lower respiratory tracts. It is caused by one of several viruses. Symptoms are fever, chills, headache, and muscular aches, followed by cold like symptoms. In comparison to the common cold, the effects of influenza are much more severe and may lead to the development of pneumonia.

Pneumonia (nu-mon’-yah) is an acute inflammation of the alveoli that may be caused by viral or bacterial infections. The alveoli become filled with fluid, pathogens, and white blood cells, which reduce space for air exchange. Blood oxygen levels may be greatly reduced. Pneumonia is one of the common causes of death among older people.

Pleurisy (pler’-i-se) is inflammation of the pleurae. It often results in a decrease in secretion of pleural fluid, which causes sharp pains with each breath. Pleurisy can also cause the opposite effect: an increase in pleural fluid secretion. This type exerts pressure on the lungs and impairs expansion of the lungs.

Tuberculosis (tu-ber”-ku-lo’-sis) is an inflammation caused by the bacterium Mycobacterium tuberculosis, which is transmitted by inhalation. When it infects the lungs, the destroyed lung tissue is replaced by dense irregular connective tissue that retards gas exchange and reduces lung elasticity. Fortunately, modern drugs are effective in treating this disease.

Non inflammatory Disorders

Lung cancer is the second most common cancer and the leading cause of death from cancer in American males and females. It usually develops from long-term exposure to irritants, and the most common irritant producing this malignancy is tobacco smoke. The link between lung cancer and cigarette smoking has been firmly established. Lung cancer metastasizes rapidly and is not usually detected until it has spread to other parts of the body. Treatment includes surgical removal of the diseased lung, if detected prior to metastasis, and chemotherapy. More than 90% of lung cancers occur in smokers, so the most effective prevention is the elimination of cigarette smoking.

Pulmonary edema is the accumulation of fluid in the lungs. It results from excessive fluid passing from alveolar capillaries into the alveoli, which may be due to congestive heart failure. Symptoms include labored breathing and a feeling of suffocation. Treatment includes administration of oxygen, diuretics, drugs that dilate the bronchioles, suctioning air passageways, and mechanical ventilation.

Pulmonary embolism refers to a blood clot or gas bubble that blocks a small artery in the lung and prevents blood from reaching a portion of a lung. Gas exchange cannot occur in the affected parts of the lung. A massive embolism affecting a large portion of a lung may cause cardiac arrest.

Infant respiratory distress syndrome (IRDS), or hyaline membrane disease, is a disease of newborn infants, especially premature infants. It results from an insufficient production of surfactant in the alveoli, leading to alveolar collapse.

At birth, the respiratory system of an infant goes through a transition from a nonfunctional, fluid-filled system to a functional, air-filled system. Normally, an infant’s first breath is the most difficult because it must open the collapsed alveoli. Succeeding breaths are easier because surfactant keeps the alveoli open after expiration. Without adequate surfactant, alveoli tend to collapse at each expiration and the infant must expend a great amount of energy to force them open at each inspiration.