The respiratory system consists of the lungs and air passages. This system is responsible for taking in oxygen, a gas needed by all body cells, and removing carbon dioxide, a gas that is a metabolic waste product produced by the cells when the cells convert food into energy. Because the body has only a 4–6-minute supply of oxygen, the respiratory system must work continuously to prevent death.

The parts of the respiratory system are the nose, pharynx, larynx, trachea, bronchi, alveoli, and lungs

The [nose](javascript://) has two openings, called nostrils or nares, through which air enters. A wall of cartilage, called the [nasal septum](javascript://), divides the nose into two hollow spaces, called [nasal cavities](javascript://). The nasal cavities are lined with a mucous membrane and have a rich blood supply. As air enters the cavities, it is warmed, filtered, and moistened. Mucus, produced by the mucous membranes, moistens the air and helps trap pathogens and dirt. Tiny, hairlike structures, called [cilia](javascript://), filter inhaled air to trap dust and other particles. The cilia then help move the mucous layer that lines the airways to push trapped particles toward the esophagus, where they can be swallowed. The olfactory receptors for the sense of smell are also located in the nose. The nasolacrimal ducts drain tears from the eye into the nose to provide additional moisture for the air.

Sinuses are cavities in the skull that surround the nasal area ([Figure 7-59](javascript://)). They are connected to the nasal cavity by short ducts. The sinuses are lined with a mucous membrane that warms and moistens air. The sinuses also provide resonance for the voice.The [pharynx](javascript://), or throat, lies directly behind the nasal cavities (refer to [Figure 7-59](javascript://)). As air leaves the nose, it enters the pharynx. The pharynx is divided into three sections. The nasopharynx is the upper portion, located behind the nasal cavities. The pharyngeal tonsils, or adenoids (lymphatic tissue), and the eustachian tube (tube to middle ear) openings are located in this section. The oropharynx is the middle section, located behind the oral cavity (mouth). This section receives both air from the nasopharynx and food and air from the mouth. The laryngopharynx is the bottom section of the pharynx. The esophagus, which carries food to the stomach, and the trachea, which carries air to and from the lungs, branch off the laryngopharynx.

The [larynx](javascript://), or voice box, lies between the pharynx and trachea. It has nine layers of cartilage. The largest, the thyroid cartilage, is commonly called the Adam’s apple. The larynx contains two folds, called vocal cords. The opening between the vocal cords is called the glottis. As air leaves the lungs, the vocal cords vibrate and produce sound. The tongue and lips act on the sound to produce speech. The [epiglottis](javascript://), a special leaflike piece of cartilage, closes the opening into the larynx during swallowing. This prevents food and liquids from entering the respiratory tract.

The [trachea](javascript://) (windpipe) is a tube extending from the larynx to the center of the chest. It carries air between the pharynx and the bronchi. A series of C-shaped cartilages (which are open on the dorsal, or back, surfaces) help keep the trachea open.

The trachea divides into two [bronchi](javascript://) near the center of the chest, a right bronchus and a left bronchus. The right bronchus is shorter, wider, and extends more vertically than the left bronchus. Each bronchus enters a lung and carries air from the trachea to the lung. In the lungs, the bronchi continue to divide into smaller and smaller bronchi until, finally, they divide into the smallest branches, called [bronchioles](javascript://). The smallest bronchioles, called terminal bronchioles, end in air sacs, called alveoli.

The [alveoli](javascript://) resemble a bunch of grapes. An adult lung contains approximately 500 million alveoli. They are made of one layer of squamous epithelial tissue and contain a rich network of blood capillaries. The capillaries allow oxygen and carbon dioxide to be exchanged between the blood and the lungs. The inner surfaces of the alveoli are covered with a lipid (fatty) substance, called surfactant, to help prevent them from collapsing.

The divisions of the bronchi and the alveoli are found in organs called [lungs](javascript://). The right lung has three sections, or lobes: the superior, the middle, and the inferior. The left lung has only two lobes: the superior and the inferior. The left lung is smaller because the heart is located toward the left side of the chest. Each lung is enclosed in a membrane, or sac, called the [pleura](javascript://). The pleura consists of two layers of serous membrane: a visceral pleura attached to the surface of the lung, and a parietal pleura attached to the chest wall. A pleural space, located between the two layers, is filled with a thin layer of pleural fluid that lubricates the membranes and prevents friction as the lungs expand during breathing. Both of the lungs, along with the heart and major blood vessels, are located in the thoracic cavity.

[Ventilation](javascript://) is the process of breathing. It involves two phases: inspiration and expiration. [Inspiration](javascript://) (inhalation) is the process of breathing in air. The diaphragm (dome-shaped muscle between the thoracic and abdominal cavities) and the intercostal muscles (between the ribs) contract and enlarge the thoracic cavity to create a vacuum. Air rushes in through the airways to the alveoli, where the exchange of gases takes place. When the diaphragm and intercostal muscles relax, the process of [expiration](javascript://) (exhalation) occurs. Air is forced out of the lungs and air passages. This process of inspiration and expiration is known as [respiration](javascript://). The process of respiration is controlled by the respiratory center in the medulla oblongata of the brain. An increased amount of carbon dioxide in the blood, or a decreased amount of oxygen as seen in certain diseases (asthma, congestive heart failure, or emphysema), causes the respiratory center to increase the rate of respiration. Although this process is usually involuntary, a person can control the rate of breathing by breathing faster or slower.

There are two main stages of respiration: external respiration and internal respiration ([Figure 7-60](javascript://)). External respiration is the exchange of oxygen and carbon dioxide between the lungs and bloodstream. Oxygen, breathed in through the respiratory system, enters the alveoli. Because the oxygen concentration in the alveoli is higher than the oxygen concentration in the blood capillaries, oxygen leaves the alveoli and enters the capillaries and the bloodstream. Carbon dioxide, a metabolic waste product, is carried in the bloodstream. Because the carbon dioxide concentration in the capillaries is higher than the carbon dioxide concentration in the alveoli, carbon dioxide leaves the capillaries and enters the alveoli, where it is expelled from the body during exhalation. Internal respiration is the exchange of carbon dioxide and oxygen between the tissue cells and the bloodstream. Oxygen is carried to the tissue cells by the blood. Because the oxygen concentration is higher in the blood than in the tissue cells, oxygen leaves the blood capillaries and enters the tissue cells. The cells then use the oxygen and nutrients to produce energy, water, and carbon dioxide. This process is called cellular respiration . Because the carbon dioxide concentration is higher in tissue cells than in the bloodstream, carbon dioxide leaves the cells and enters the bloodstream to be transported back to the lungs, where external respiration takes place.

Asthma

Asthma is a chronic inflammatory disorder of the airways, usually caused by a sensitivity to an allergen such as dust, pollen, an animal, medications, or a food. Stress, overexertion, and infection can also cause an asthma attack, during which bronchospasms narrow the openings of the bronchioles, mucus production increases, and edema develops in the mucosal lining. Symptoms of an asthma attack include dyspnea (difficult breathing), wheezing, coughing accompanied by expectoration of sputum, and tightness in the chest. Treatment methods include bronchodilators (to enlarge the bronchioles), anti-inflammatory medications, allergy shots and medications, epinephrine, and oxygen therapy. In severe cases, bronchial thermoplasty may be helpful. An electrode is used to heat the inside of the airways to reduce smooth muscle and lessen the ability of the airway to tighten. Identification and elimination of or desensitization to allergens are important in preventing asthma attacks.

Bronchitis

Bronchitis is an inflammation of the bronchi and bronchial tubes. Acute bronchitis is very common and frequently develops from a cold or the flu. It is usually caused by a viral infection. It is caused by bacteria in only about 10 percent of the cases. It is characterized by a productive cough, dyspnea, rales (bubbly or noisy breath sounds), chest pain, and fever. If it is bacterial, it is treated with antibiotics. Other treatments include expectorants (to remove excessive mucus), nonsteroidal anti-inflammatory drugs (for fever and sore throat), decongestants, cough suppressants, rest, and drinking large amounts of water. Chronic bronchitis results from frequent attacks of acute bronchitis and long-term exposure to pollutants or smoking. It is characterized by chronic inflammation, damaged cilia, and enlarged mucous glands. Symptoms include excessive mucus resulting in a productive cough, wheezing, dyspnea, chest pain, and prolonged air expiration. Although there is no cure, antibiotics (for bacterial infections), bronchodilators, and/or respiratory therapy (including breathing exercises) are used in treatment.

Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a term used to describe any chronic lung disease that results in obstruction of the airways and limitation of air flow. Disorders such as chronic asthma, chronic bronchitis, emphysema, and tuberculosis lead to COPD. Smoking is the primary cause, but allergies and chronic respiratory infections are also factors. Symptoms include shortness of breath, wheezing, chest tightness, chronic cough, and physical impairment. Treatment methods include bronchodilators, mucolytics (to loosen mucus secretions), cough medications, supplemental oxygen, and pulmonary rehabilitation to optimize respiratory function. The flu and pneumonia vaccines should always be given to prevent infections and exacerbation of COPD. The prognosis is poor because damage to the lungs causes a deterioration of pulmonary function, leading to respiratory failure and death.

Emphysema

Emphysema is a noninfectious, chronic respiratory condition that occurs when the walls of the alveoli deteriorate and lose their elasticity, resulting in an abnormal and permanent enlargement of the airspaces. Carbon dioxide remains trapped in the alveoli, and there is poor exchange of gases. The most common causes are heavy smoking and prolonged exposure to air pollutants. Symptoms include dyspnea, a feeling of suffocation, pain, barrel chest, chronic cough, cyanosis, rapid respirations accompanied by prolonged expirations, and eventual respiratory failure and death. Although there is no cure, treatment methods include bronchodilators, inhaled steroids, breathing exercises, prompt treatment of respiratory infections, oxygen therapy, respiratory therapy, and avoidance of smoking. In advanced cases, lung volume reduction surgery (LVRS) can be done to remove areas of diseased lung. In severe cases, a lung transplant may be an option.

Epistaxis

Epistaxis, or a nosebleed, occurs when capillaries in the nose become congested and bleed. It can be caused by an injury or blow to the nose, hypertension, chronic infection, anticoagulant drugs, nose-picking, dry or cold air, and blood diseases such as hemophilia and leukemia. Compressing the nostrils toward the septum; elevating the head and tilting it slightly forward; and applying cold compresses will usually control epistaxis. A local vasoconstrictive agent can be used to reduce bleeding time. Sometimes it is necessary to insert nasal packs or cauterize (burn and destroy) the bleeding vessels. Treatment of any underlying cause, such as hypertension, is important in preventing epistaxis.

Influenza

Influenza, or flu, is a highly contagious viral infection of the upper respiratory system. Onset is sudden, and symptoms include chills, fever, a cough, sore throat, runny nose, muscle pain, and fatigue. Treatment methods include bed rest, fluids, analgesics (for pain), and antipyretics (for fever). Antiviral medications (Tamiflu), should be started with the onset of symptoms. These drugs can injure the virus and fight the infection, shortening the duration and severity of the illness. Antibiotics are not effective against the viruses that cause influenza, but they are sometimes given to prevent secondary infections such as pneumonia. The CDC recommends that everyone 6 months and older receive an annual flu vaccine. Because many different viruses cause influenza, vaccines are developed each year to immunize against the most common viruses identified.

Laryngitis

Laryngitis is an inflammation of the larynx and vocal cords. It can be caused by a viral infection, vocal cord strain (screaming), or irritation. It frequently occurs in conjunction with other respiratory infections. Symptoms include hoarseness or loss of voice, sore throat, and dysphagia (difficult swallowing). Treatment methods include rest, limited voice use, fluids, corticosteroids (to decrease vocal cord swelling), and salt water gargles. Almost all cases are viral and will not be cured with antibiotics.

Lung Cancer

Lung cancer is the leading cause of cancer death in both men and women, and is the most common type of cancer worldwide ([Figure 7-61](javascript://)). It is a preventable disease because the main cause is exposure to carcinogens in tobacco, either through smoking or through exposure to “second-hand” smoke. Other causes include environmental toxins (asbestos) and radiation from treatment of another cancer. Three common types of lung cancer include small cell, squamous cell, and adenocarcinoma. In the early stages, there are no symptoms. In later stages, symptoms include a chronic cough, hemoptysis (coughing up blood-tinged sputum), dyspnea, fatigue, weight loss, and chest pain. The prognosis (outcome) for lung cancer patients is poor because the disease is usually advanced before it is diagnosed. Treatment includes surgical removal of the cancerous sections of the lung, radiation, and/or chemotherapy.

Lung cancer is the most common type of cancer worldwide, and it is a preventable disease.

Pleurisy

Pleurisy is an inflammation of the pleura, or membranes, of the lungs. The double membrane pleura layers rub when inflamed, causing sharp stabbing pain while breathing. It usually occurs in conjunction with pneumonia or other lung infections and is usually viral. Other symptoms include crepitation (grating sounds in the lungs), dyspnea, and fever. Treatment methods include rest and medications to relieve pain and inflammation. If fluid collects in the pleural space, a thoracentesis (withdrawal of fluid through a needle) is performed to remove the fluid and prevent compression of the lungs.

Pneumonia

Pneumonia is an inflammation or infection of the lungs characterized by exudate (a buildup of fluid) in the alveoli. It is usually caused by bacteria, viruses, protozoa, or chemicals. It often mimics the flu with symptoms being chills, fever, chest pain, productive cough, dyspnea, muscle pain, and fatigue. Treatment methods include bed rest, oxygen therapy, fluids, antibiotics (if indicated), respiratory therapy, and/or pain medication. The flu and pneumonia vaccines are both helpful in preventing pneumonia.

Rhinitis

Rhinitis is an inflammation of the nasal mucous membrane, resulting in a runny nose, watery eyes, sneezing, soreness, and congestion. Common causes are viral respiratory infections and allergens. Treatment consists of administering fluids and medications to relieve congestion and inflammation. Rhinitis is usually self-limiting.

Sinusitis

Sinusitis is an inflammation of the mucous membrane lining the sinuses. One or more sinuses may be affected. Sinusitis is usually caused by a virus, and less often by a bacteria. Symptoms include headache, facial or teeth pain and pressure, dizziness, thick nasal discharge, congestion, and loss of voice resonance. Treatment methods include analgesics (for pain), antibiotics (if indicated), decongestants (medications to loosen secretions), and moist inhalations. In more serious cases, balloon sinuplasty can be performed to expand the opening of the sinuses and improve drainage. Functional endoscopic sinus surgery (FESS) can be done to remove obstructions and allow for normal sinus drainage.

Sleep Apnea

Sleep apnea is a condition in which an individual stops breathing while asleep, causing a measurable decrease in blood oxygen levels. There are two main kinds of sleep apnea: obstructive and central. Obstructive sleep apnea is caused by a blockage in the air passage that occurs when the muscles that keep the airway open relax and allow the tongue and palate to block the airway. Central sleep apnea is caused by a disorder in the respiratory control center of the brain. The condition is more common in men. Factors such as obesity, hypertension, smoking, alcohol ingestion, and/or the use of sedatives may increase the severity. Sleep apnea is diagnosed when more than 5 periods of apnea lasting at least 10 seconds each occur during 1 hour of sleep. The periods of apnea reduce the blood oxygen level. This causes the brain to awaken the individual, who then gasps for air and snores loudly. This interruption of the sleep cycle leads to excessive tiredness and drowsiness during the day. Treatment involves losing weight, abstaining from smoking and the use of alcohol or sedatives, and sleeping on the side or stomach. An oral appliance or mouth piece designed to maintain airway patency may be helpful if worn while sleeping. In more severe cases of obstructive sleep apnea, a continuous positive airway pressure, or CPAP (pronounced see-pap), is used to deliver pressure to the airway to keep the airway open while the individual sleeps ([Figure 7-62](javascript://)). The CPAP consists of a mask that is fit securely against the face. Tubing connects the mask with a blower device that can be adjusted to deliver air at different levels of pressure. If other treatments are ineffective, a maxillomandibular advancement surgery (MMA) may be performed to move the jaw forward. The obstructing tissue may be surgically removed by uvulopalatopharyngoplasty (UPPP). In severe life-threatening cases, a tracheostomy (surgical opening in the neck) must be performed. Treatment of central sleep apnea usually involves the use of medications to stimulate breathing.

The continuous positive airway pressure (CPAP) mask attaches to a blower device that uses air pressure to keep the airway open and prevent sleep apnea.

Tuberculosis

Tuberculosis (TB) is an infectious lung disease caused by the bacterium Mycobacterium tuberculosis. At times, white blood cells surround the invading TB organisms and wall them off, creating nodules, called tubercles, in the lungs. The TB organisms remain dormant in the tubercles but can cause an active case of TB later, if body resistance is lowered (as with HIV, or cancer). Symptoms of an active case of TB include fatigue, fever, night sweats, weight loss, hemoptysis (coughing up blood-tinged sputum), and chest pain. Treatment includes administering drugs for one or more years to destroy the bacteria. In cases where there is massive hemoptysis, bronchial artery embolization may be required. Good nutrition and rest are also important. In recent years, a new strain of the TB bacteria resistant to drug therapy has created concern that TB will become a widespread infectious disease again.

Upper Respiratory Infection

An upper respiratory infection (URI), or common cold, is an inflammation of the mucous membrane lining the upper respiratory tract. Caused by viruses, URIs are highly contagious. Symptoms include fever, runny nose, watery eyes, congestion, sore throat, and hacking cough. There is no cure, and symptoms usually last approximately one week. Analgesics (for pain), antipyretics (for fever), rest, vitamin C, increased fluid intake, and antihistamines (to relieve congestion) are used to treat the symptoms.

Lungs and Air Passages

1. Nose, pharynx, *larynx, trachea, bronchi, alveoli and lungs

2. Responsible for:

   1. Taking in *O2 (needed by all body cells)

   2. Removing *CO2 (metabolic waste product)

3. Body has 4-6 minute supply of O2

Must work continuously or death will occur

Paranasal Sinuses

1. Hollow *air-containing spaces within the skull

2. Cavities in the skull around the nasal area

3. Connected to the nasal cavity by short ducts

4. Lined with mucous membrane that warms and moistens air

5. Provide *resosance for the voiceNose

6. Has 2 nostrils or nares

   1. Openings through which *air enters

   2. Removing CO2 (metabolic waste product)

7. Nasal septum

   1. Partition or wall of *cartilage

   2. Divides the nose into 2 hollow spaces called nasal cavities

Nasal Cavities

1. Lined with mucous membrane

2. Rich *blood supply

3. As air enters it is warmed, filtered and moistened

4. Mucous also helps trap pathogens and dirt

5. Cilia: tiny hair-like structures which also trap dirt and pathogens, pushing them toward the *esophogus to be swallowed

6. Olfactory receptors for the sense of *smell

7. Nasolacrimal ducts drain tears from the eye into the nose to provide additional moisture for the air

Pharynx

1. The *throat

2. Lies directly behind the nasal cavities

3. As air leaves the nose it enters the pharynx

4. Has three sections: **on next slide**

Pharynx has 3 sections:

1. *nasopharynx

   1. Upper portion behind the nasal cavities

2. *oropharynx

   1. Middle section located behind the oral cavity

   2. Receives both air from the nasopharynx and food and air from the mouth

3. *Laryngopharnyx

   1. Bottom section of the pharynx

   2. Branches into the trachea, which carries air to and from the lungs and esophagus

Epiglottis

1. A flap of *cartilage attached to the root of the tongue

2. Prevents choking or aspiration of food

3. Acts as a lid over the opening of the larynx

4. During swallowing when food and liquid move through the throat, the epiglottis closes over the *larynx

Larynx

1. Voice box

2. Lies between the pharynx and trachea

3. Has a framework of cartilage commonly called the “*Adams apple”

4. Contains two folds called vocal cords

   1. Opening between the vocal cords is the glottis

   2. As air leaves the lungs, the vocal cords *vibrate and produce sound

   3. Tongue and lips act on the sound to produce speech

Trachea

1. Windpipe

2. Tube extending from the larynx to the center of the chest (about *4.5 long)

3. Carries air between the *pharynx and bronchi

4. Series of c-shaped cartilages, which are open on the dorsal or back surface, and help keep the trachea open

Bronchi

1. Two divisions of the *trachea near the center of the chest

   1. Right and left bronchus (singular)

   2. Right bronchus is shorter, wider and extends more vertically than the left bronchus

2. Each bronchus enters a *lung and carries air from the trachea to the lungs

3. In the lungs, the bronchi continue to divide into smaller and smaller bronchi

4. Smaller branches are called *bronchioles

5. Smallest bronchioles, called terminal bronchioles; end in the air sacs called alveoli

Alveoli

1. Air sacs that resemble a bunch of *grapes

2. Adult lung contains approximately 300 million alveoli

3. Made of one layer of squamous epithelium tissue

4. Contains a rich network of blood capillaries

5. Capillaries allow O2 and CO2 to be *exchanged between the blood and the lungs

6. Inner surface of alveoli are covered with *surfactant

   1. Lipid or fatty substance

   2. Helps prevent alveoli from collapsing

Lungs

1. Organs that contain divisions of the bronchi and alveoli

2. Right lung has 3 sections or *lobes: superior, middle and inferior

3. Left lung has only *two lobes, superior and inferior

4. Left lung is smaller because the heart lies more to the left side of the chest

5. Both the lungs are located in the thoracic cavity

6. Apex: *uppermost part of the lung

7. Base: lower part of the lung

8. Hilum: the midline region in which blood vessels, nerves, lymphatic tissue, and bronchial tubes enter and exit the lung

9. The lungs extend form the collarbone to the diaphragm

Diaphragm

1. A muscular partition

2. Separates the thoracic from the *abdominal cavity

3. Aids in the process of breathing

   1. Contracts

      1. Moves *downlward, enlarging the area in the thoracic cavity

      2. Decreasing internal air pressure, so that air flows into the lungs to equalize the pressure

   2. Relaxes

      1. When the lungs are full, the diaphragm relaxes and elevates

      2. Makes the area in the thoracic cavity smaller, thus increasing air pressure in the chest

      3. Air is expelled out of the lungs to *equalize pressure

Pathway of air

1. Nose

2. Nasal cavities and paranasal sinuses

3. pharynx (adenoids and tonsils)

4. Larnyx

5. Trachea

6. Bronchi

7. Bronchioles

8. Alveoli

9. Lung capillaries

Inspiration + Expiration = *Respiration

1. The mechanical process of breathing

2. The exchange of air between the lungs and the external environment

3. Process is controlled by the respiratory center in the medulla oblongata of the brain

Respiration is a Vital Sign

1. Normal adult respiration rate is *12-20 breaths/minute

2. How do we know if a person is breathing? *we can see the chest rise and fall \