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StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-.

StatPearls [Internet].

Case study: 33-year-old female presents with chronic sob and cough.

Sandeep Sharma ; Muhammad F. Hashmi ; Deepa Rawat .

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Last Update: February 20, 2023 .

• Case Presentation

History of Present Illness:  A 33-year-old white female presents after admission to the general medical/surgical hospital ward with a chief complaint of shortness of breath on exertion. She reports that she was seen for similar symptoms previously at her primary care physician’s office six months ago. At that time, she was diagnosed with acute bronchitis and treated with bronchodilators, empiric antibiotics, and a short course oral steroid taper. This management did not improve her symptoms, and she has gradually worsened over six months. She reports a 20-pound (9 kg) intentional weight loss over the past year. She denies camping, spelunking, or hunting activities. She denies any sick contacts. A brief review of systems is negative for fever, night sweats, palpitations, chest pain, nausea, vomiting, diarrhea, constipation, abdominal pain, neural sensation changes, muscular changes, and increased bruising or bleeding. She admits a cough, shortness of breath, and shortness of breath on exertion.

Social History: Her tobacco use is 33 pack-years; however, she quit smoking shortly prior to the onset of symptoms, six months ago. She denies alcohol and illicit drug use. She is in a married, monogamous relationship and has three children aged 15 months to 5 years. She is employed in a cookie bakery. She has two pet doves. She traveled to Mexico for a one-week vacation one year ago.

Allergies:  No known medicine, food, or environmental allergies.

Past Medical History: Hypertension

Past Surgical History: Cholecystectomy

Medications: Lisinopril 10 mg by mouth every day

Physical Exam:

Vitals: Temperature, 97.8 F; heart rate 88; respiratory rate, 22; blood pressure 130/86; body mass index, 28

General: She is well appearing but anxious, a pleasant female lying on a hospital stretcher. She is conversing freely, with respiratory distress causing her to stop mid-sentence.

Respiratory: She has diffuse rales and mild wheezing; tachypneic.

Cardiovascular: She has a regular rate and rhythm with no murmurs, rubs, or gallops.

Gastrointestinal: Bowel sounds X4. No bruits or pulsatile mass.

• Initial Evaluation

Laboratory Studies:  Initial work-up from the emergency department revealed pancytopenia with a platelet count of 74,000 per mm3; hemoglobin, 8.3 g per and mild transaminase elevation, AST 90 and ALT 112. Blood cultures were drawn and currently negative for bacterial growth or Gram staining.

Chest X-ray

Impression:  Mild interstitial pneumonitis

• Differential Diagnosis
• Aspiration pneumonitis and pneumonia
• Bacterial pneumonia
• Immunodeficiency state and Pneumocystis jiroveci pneumonia
• Carcinoid lung tumors
• Tuberculosis
• Viral pneumonia
• Chlamydial pneumonia
• Coccidioidomycosis and valley fever
• Recurrent Legionella pneumonia
• Mediastinal cysts
• Mediastinal lymphoma
• Recurrent mycoplasma infection
• Pancoast syndrome
• Pneumococcal infection
• Sarcoidosis
• Small cell lung cancer
• Aspergillosis
• Blastomycosis
• Histoplasmosis
• Actinomycosis
• Confirmatory Evaluation

CT of the chest was performed to further the pulmonary diagnosis; it showed a diffuse centrilobular micronodular pattern without focal consolidation.

On finding pulmonary consolidation on the CT of the chest, a pulmonary consultation was obtained. Further history was taken, which revealed that she has two pet doves. As this was her third day of broad-spectrum antibiotics for a bacterial infection and she was not getting better, it was decided to perform diagnostic bronchoscopy of the lungs with bronchoalveolar lavage to look for any atypical or rare infections and to rule out malignancy (Image 1).

Bronchoalveolar lavage returned with a fluid that was cloudy and muddy in appearance. There was no bleeding. Cytology showed Histoplasma capsulatum .

Based on the bronchoscopic findings, a diagnosis of acute pulmonary histoplasmosis in an immunocompetent patient was made.

Pulmonary histoplasmosis in asymptomatic patients is self-resolving and requires no treatment. However, once symptoms develop, such as in our above patient, a decision to treat needs to be made. In mild, tolerable cases, no treatment other than close monitoring is necessary. However, once symptoms progress to moderate or severe, or if they are prolonged for greater than four weeks, treatment with itraconazole is indicated. The anticipated duration is 6 to 12 weeks total. The response should be monitored with a chest x-ray. Furthermore, observation for recurrence is necessary for several years following the diagnosis. If the illness is determined to be severe or does not respond to itraconazole, amphotericin B should be initiated for a minimum of 2 weeks, but up to 1 year. Cotreatment with methylprednisolone is indicated to improve pulmonary compliance and reduce inflammation, thus improving work of respiration. [1] [2] [3]

Histoplasmosis, also known as Darling disease, Ohio valley disease, reticuloendotheliosis, caver's disease, and spelunker's lung, is a disease caused by the dimorphic fungi  Histoplasma capsulatum native to the Ohio, Missouri, and Mississippi River valleys of the United States. The two phases of Histoplasma are the mycelial phase and the yeast phase.

Etiology/Pathophysiology 

Histoplasmosis is caused by inhaling the microconidia of  Histoplasma  spp. fungus into the lungs. The mycelial phase is present at ambient temperature in the environment, and upon exposure to 37 C, such as in a host’s lungs, it changes into budding yeast cells. This transition is an important determinant in the establishment of infection. Inhalation from soil is a major route of transmission leading to infection. Human-to-human transmission has not been reported. Infected individuals may harbor many yeast-forming colonies chronically, which remain viable for years after initial inoculation. The finding that individuals who have moved or traveled from endemic to non-endemic areas may exhibit a reactivated infection after many months to years supports this long-term viability. However, the precise mechanism of reactivation in chronic carriers remains unknown.

Infection ranges from an asymptomatic illness to a life-threatening disease, depending on the host’s immunological status, fungal inoculum size, and other factors. Histoplasma  spp. have grown particularly well in organic matter enriched with bird or bat excrement, leading to the association that spelunking in bat-feces-rich caves increases the risk of infection. Likewise, ownership of pet birds increases the rate of inoculation. In our case, the patient did travel outside of Nebraska within the last year and owned two birds; these are her primary increased risk factors. [4]

Non-immunocompromised patients present with a self-limited respiratory infection. However, the infection in immunocompromised hosts disseminated histoplasmosis progresses very aggressively. Within a few days, histoplasmosis can reach a fatality rate of 100% if not treated aggressively and appropriately. Pulmonary histoplasmosis may progress to a systemic infection. Like its pulmonary counterpart, the disseminated infection is related to exposure to soil containing infectious yeast. The disseminated disease progresses more slowly in immunocompetent hosts compared to immunocompromised hosts. However, if the infection is not treated, fatality rates are similar. The pathophysiology for disseminated disease is that once inhaled, Histoplasma yeast are ingested by macrophages. The macrophages travel into the lymphatic system where the disease, if not contained, spreads to different organs in a linear fashion following the lymphatic system and ultimately into the systemic circulation. Once this occurs, a full spectrum of disease is possible. Inside the macrophage, this fungus is contained in a phagosome. It requires thiamine for continued development and growth and will consume systemic thiamine. In immunocompetent hosts, strong cellular immunity, including macrophages, epithelial, and lymphocytes, surround the yeast buds to keep infection localized. Eventually, it will become calcified as granulomatous tissue. In immunocompromised hosts, the organisms disseminate to the reticuloendothelial system, leading to progressive disseminated histoplasmosis. [5] [6]

Symptoms of infection typically begin to show within three to17 days. Immunocompetent individuals often have clinically silent manifestations with no apparent ill effects. The acute phase of infection presents as nonspecific respiratory symptoms, including cough and flu. A chest x-ray is read as normal in 40% to 70% of cases. Chronic infection can resemble tuberculosis with granulomatous changes or cavitation. The disseminated illness can lead to hepatosplenomegaly, adrenal enlargement, and lymphadenopathy. The infected sites usually calcify as they heal. Histoplasmosis is one of the most common causes of mediastinitis. Presentation of the disease may vary as any other organ in the body may be affected by the disseminated infection. [7]

The clinical presentation of the disease has a wide-spectrum presentation which makes diagnosis difficult. The mild pulmonary illness may appear as a flu-like illness. The severe form includes chronic pulmonary manifestation, which may occur in the presence of underlying lung disease. The disseminated form is characterized by the spread of the organism to extrapulmonary sites with proportional findings on imaging or laboratory studies. The Gold standard for establishing the diagnosis of histoplasmosis is through culturing the organism. However, diagnosis can be established by histological analysis of samples containing the organism taken from infected organs. It can be diagnosed by antigen detection in blood or urine, PCR, or enzyme-linked immunosorbent assay. The diagnosis also can be made by testing for antibodies again the fungus. [8]

Pulmonary histoplasmosis in asymptomatic patients is self-resolving and requires no treatment. However, once symptoms develop, such as in our above patient, a decision to treat needs to be made. In mild, tolerable cases, no treatment other than close monitoring is necessary. However, once symptoms progress to moderate or severe or if they are prolonged for greater than four weeks, treatment with itraconazole is indicated. The anticipated duration is 6 to 12 weeks. The patient's response should be monitored with a chest x-ray. Furthermore, observation for recurrence is necessary for several years following the diagnosis. If the illness is determined to be severe or does not respond to itraconazole, amphotericin B should be initiated for a minimum of 2 weeks, but up to 1 year. Cotreatment with methylprednisolone is indicated to improve pulmonary compliance and reduce inflammation, thus improving the work of respiration.

The disseminated disease requires similar systemic antifungal therapy to pulmonary infection. Additionally, procedural intervention may be necessary, depending on the site of dissemination, to include thoracentesis, pericardiocentesis, or abdominocentesis. Ocular involvement requires steroid treatment additions and necessitates ophthalmology consultation. In pericarditis patients, antifungals are contraindicated because the subsequent inflammatory reaction from therapy would worsen pericarditis.

Patients may necessitate intensive care unit placement dependent on their respiratory status, as they may pose a risk for rapid decompensation. Should this occur, respiratory support is necessary, including non-invasive BiPAP or invasive mechanical intubation. Surgical interventions are rarely warranted; however, bronchoscopy is useful as both a diagnostic measure to collect sputum samples from the lung and therapeutic to clear excess secretions from the alveoli. Patients are at risk for developing a coexistent bacterial infection, and appropriate antibiotics should be considered after 2 to 4 months of known infection if symptoms are still present. [9]

Prognosis 

If not treated appropriately and in a timely fashion, the disease can be fatal, and complications will arise, such as recurrent pneumonia leading to respiratory failure, superior vena cava syndrome, fibrosing mediastinitis, pulmonary vessel obstruction leading to pulmonary hypertension and right-sided heart failure, and progressive fibrosis of lymph nodes. Acute pulmonary histoplasmosis usually has a good outcome on symptomatic therapy alone, with 90% of patients being asymptomatic. Disseminated histoplasmosis, if untreated, results in death within 2 to 24 months. Overall, there is a relapse rate of 50% in acute disseminated histoplasmosis. In chronic treatment, however, this relapse rate decreases to 10% to 20%. Death is imminent without treatment.

• Pearls of Wisdom

While illnesses such as pneumonia are more prevalent, it is important to keep in mind that more rare diseases are always possible. Keeping in mind that every infiltrates on a chest X-ray or chest CT is not guaranteed to be simple pneumonia. Key information to remember is that if the patient is not improving under optimal therapy for a condition, the working diagnosis is either wrong or the treatment modality chosen by the physician is wrong and should be adjusted. When this occurs, it is essential to collect a more detailed history and refer the patient for appropriate consultation with a pulmonologist or infectious disease specialist. Doing so, in this case, yielded workup with bronchoalveolar lavage and microscopic evaluation. Microscopy is invaluable for definitively diagnosing a pulmonary consolidation as exemplified here where the results showed small, budding, intracellular yeast in tissue sized 2 to 5 microns that were readily apparent on hematoxylin and eosin staining and minimal, normal flora bacterial growth. 

• Enhancing Healthcare Team Outcomes

This case demonstrates how all interprofessional healthcare team members need to be involved in arriving at a correct diagnosis. Clinicians, specialists, nurses, pharmacists, laboratory technicians all bear responsibility for carrying out the duties pertaining to their particular discipline and sharing any findings with all team members. An incorrect diagnosis will almost inevitably lead to incorrect treatment, so coordinated activity, open communication, and empowerment to voice concerns are all part of the dynamic that needs to drive such cases so patients will attain the best possible outcomes.

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Histoplasma Contributed by Sandeep Sharma, MD

Disclosure: Sandeep Sharma declares no relevant financial relationships with ineligible companies.

Disclosure: Muhammad Hashmi declares no relevant financial relationships with ineligible companies.

Disclosure: Deepa Rawat declares no relevant financial relationships with ineligible companies.

This book is distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ), which permits others to distribute the work, provided that the article is not altered or used commercially. You are not required to obtain permission to distribute this article, provided that you credit the author and journal.

• Cite this Page Sharma S, Hashmi MF, Rawat D. Case Study: 33-Year-Old Female Presents with Chronic SOB and Cough. [Updated 2023 Feb 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-.

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116 13.1 Case Study: Respiratory System and Gas Exchange

Created by CK-12 Foundation/Adapted by Christine Miller

 Case Study: Cough That Won’t Quit

Three weeks ago, 20-year-old Erica came down with symptoms typical of the common cold. She had a runny nose, fatigue, and a mild cough. Her symptoms were starting to improve, but recently, her cough has been getting worse. She is coughing up a lot of thick mucus, her throat is sore from frequent coughing, and her chest feels very congested. According to her grandmother, Erica has a “chest cold.” Erica is a smoker and wonders if her habit is making her cough worse. She decides that it’s time to see a doctor.

Dr. Choo examines Erica and asks about her symptoms and health history. She checks the level of oxygen in Erica’s blood by attaching a device called a pulse oximeter to Erica’s finger.

Dr. Choo concludes that Erica has bronchitis , which is an infection that commonly occurs after a person has a cold or flu. Bronchitis is sometimes referred to as a “chest cold,” so Erica’s grandmother was right! Bronchitis causes inflammation and a build up of mucus in the bronchial tubes in the chest.

Because bronchitis is usually caused by viruses and not bacteria , Dr. Choo tells Erica that antibiotics are not likely to help. Instead, she recommends that Erica try to thin out and remove the mucus by drinking plenty of fluids and using a humidifier or spending time in a steamy shower. She recommends that Erica get plenty of rest as well.

Dr. Choo also tells Erica some things not to do — most importantly, to stop smoking while she is sick, and to try to quit smoking in the long-term. She explains that smoking can make people more susceptible to bronchitis and can hinder recovery. Finally, she advises Erica to avoid taking over-the-counter cough suppressant medication.

As you read this chapter about the respiratory system, you will be able to better understand what bronchitis is, and why Dr. Choo made the treatment recommendations that she did. At the end of the chapter, you will learn more about acute bronchitis, which is the type that Erica has. This information may come in handy to you personally, because chances are high that you will get this common infection at some point in your life — there are millions of cases of bronchitis every year!

Chapter Overview: Respiratory System

In this chapter, you will learn about the respiratory system — the system that exchanges gases (such as oxygen and carbon dioxide) between the body and the outside air. Specifically, you will learn about:

• The process of respiration, in which oxygen moves from the outside air into the body and carbon dioxide and other waste gases move from inside the body into the outside air.
• The organs of the respiratory system, including the lungs, bronchial tubes, and the rest of the respiratory tract.
• How the respiratory tract protects itself from pathogens and other potentially harmful substances in the air.
• How the rate of breathing is regulated to maintain homeostasis of blood gases and pH.
• How ventilation, or breathing, allows us to inhale air into the body and exhale air out of the body.
• The conscious and unconscious control of breathing.
• Nasal breathing compared to mouth breathing.
• What happens when a person is drowning.
• How gas exchange occurs between the air and blood in the alveoli of the lungs, and between the blood and cells throughout the body.
• Disorders of the respiratory system, including asthma, pneumonia, chronic obstructive pulmonary disease (COPD), and lung cancer.
• The negative health effects of smoking.

As you read the chapter, think about the following questions:

• Where are the bronchial tubes? What is their function?
• What is the function of mucus? Why can too much mucus be a bad thing?
• Why did Dr. Choo check Erica’s blood oxygen level?
• Why do you think Dr. Choo warned Erica to avoid cough suppressant medications?
• How does acute bronchitis compare to chronic bronchitis? How do they both relate to smoking?

Attributions

Figure 13.1.1

Cold/ Look into my eyes forever [photo] by Spencer Backman on Unsplash is used under the Unsplash License (https://unsplash.com/license).

Figure 13.1.2

Wrist-oximeter by UusiAjaja on Wikimedia Commons is used under a CC0 1.0 Universal Public Domain Dedication (https://creativecommons.org/publicdomain/zero/1.0/deed.en) license.

Mayo Clinic Staff. (n.d.). Bronchitis [online article]. Mayoclinic.org. https://www.mayoclinic.org/diseases-conditions/bronchitis/symptoms-causes/syc-20355566

Inflammation of the mucous membrane in the bronchial tubes. It typically causes bronchospasm and coughing

A tiny, nonliving particle that contains nucleic acids but lacks other characteristics of living cells and may cause human disease.

Any member of a large group of unicellular microorganisms which have cell walls but lack organelles and an organized nucleus, including some which can cause disease.

The body system responsible for taking in oxygen and expelling carbon dioxide. The primary organs of the respiratory system are the lungs, which carry out this exchange of gases as we breathe.

Human Biology Copyright © 2020 by Christine Miller is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License , except where otherwise noted.

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7.6: Case Study Conclusion: Bronchitis and Chapter Summary

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Case Study Conclusion: Cough That Won't Quit

The little child shown in Figure \(\PageIndex{1}\) seems to be enjoying the air coming out of a humidifier. Inhaling the moist air from a humidifier or steamy shower can feel particularly good if you have a respiratory system infection, such as bronchitis. The moist air helps to loosen and thin mucus in the respiratory system, allowing you to breathe easier.

At the beginning of this chapter, you learned about Sacheen, who developed acute bronchitis after getting a cold. She had a worsening cough, sore throat due to coughing, and chest congestion. She was also coughing up thick mucus.

Acute bronchitis usually occurs after a cold or flu, usually due to the same viruses that cause cold or flu. Because bronchitis is not usually caused by bacteria (although it can be), antibiotics are not an effective treatment in most cases.

Bronchitis affects the bronchial tubes, which, as you have learned, are air passages in the lower respiratory tract. The main bronchi branch off of the trachea and then branch into smaller bronchi and then bronchioles. In bronchitis, the walls of the bronchi become inflamed, which makes them narrower. Also, there is excessive production of mucus in the bronchi, which further narrows the pathway through which can flow. Figure \(\PageIndex{2}\) shows how bronchitis affects the bronchial tubes.

The function of mucus is to trap pathogens and other potentially dangerous particles that enter the respiratory system from the air. However, when too much mucus is produced in response to an infection (as in the case of bronchitis), it can interfere with normal airflow. The body responds by coughing as it tries to rid itself of the pathogen-laden mucus.

The treatment for most cases of bronchitis involves thinning and loosening the mucus so that it can be effectively coughed out of the airways. This can be done by drinking plenty of fluids, using humidifiers or steam, and in some cases, using over-the-counter medications such as expectorants that are found in some cough medicines. This is why Dr. Tsosie recommended some of these treatments to Sacheen and also warned against using cough suppressants. Cough suppressants work on the nervous system to suppress the cough reflex. When a patient has a “productive” cough—i.e. they are coughing up mucus—doctors generally advise them to not take cough suppressants so that they can cough the mucus out of their bodies.

When Dr. Tsosie was examining Sacheen, she used a pulse oximeter to measure the oxygen level in her blood. Why did she do this? As you have learned, the bronchial tubes branch into bronchioles, which ultimately branch into the alveoli of the lungs. The alveoli are where gas exchange occurs between the air and the blood to take in oxygen and remove carbon dioxide and other wastes. By checking Sacheen’s blood oxygen level, Dr. Tsosie was making sure that her clogged airways were not impacting her level of much-needed oxygen.

Sacheen has acute bronchitis, but you may recall that chronic bronchitis was discussed earlier in this chapter as a term that describes the symptoms of chronic obstructive pulmonary disease (COPD). COPD is often due to tobacco smoking and causes damage to the walls of the alveoli, whereas acute bronchitis typically occurs after a cold or flu and involves inflammation and mucus build-up in the bronchial tubes. As implied by the difference in their names, chronic bronchitis is an ongoing, long-term condition, while acute bronchitis is likely to resolve relatively quickly with proper rest and treatment.

However, Sacheen smokes cigarettes, so she is more likely to develop chronic respiratory conditions such as COPD. As you have learned, smoking damages the respiratory system as well as many other systems of the body. Smoking increases the risk of respiratory infections, including bronchitis and flu, due to its damaging effects on the respiratory and immune systems. Dr. Tsosie strongly encouraged Sacheen to quit smoking, not only so that her acute bronchitis resolves, but so that she can avoid future infections and other negative health outcomes associated with smoking, including COPD and lung cancer.

As you have learned in this chapter, the respiratory system is critical to carry out the gas exchange necessary for life’s functions and to protect the body from pathogens and other potentially harmful substances in the air. But this ability to interface with the outside air has a cost. The respiratory system is prone to infections, as well as damage and other negative effects from allergens, mold, air pollution, and cigarette smoke. Although exposure to most of these things cannot be avoided, not smoking is an important step you can take to protect this organ system—as well as many other systems of your body.

Chapter Summary

In this chapter, you learned about the respiratory system. Specifically, you learned that:

• Respiration is the process in which oxygen moves from the outside air into the body and carbon dioxide and other waste gases move from inside the body into the outside air. It involves two subsidiary processes: ventilation and gas exchange.
• The upper respiratory tract includes the nasal cavity, pharynx, and larynx. All of these organs are involved in conduction or the movement of air into and out of the body. Incoming air is also cleaned, humidified, and warmed as it passes through the upper respiratory tract. The larynx is also called the voice box because it contains the vocal cords, which are needed to produce vocal sounds.
• The lower respiratory tract includes the trachea, bronchi and bronchioles, and the lungs. The trachea, bronchi, and bronchioles are involved in conduction. Gas exchange takes place only in the lungs, which are the largest organs of the respiratory tract. Lung tissue consists mainly of tiny air sacs called alveoli, which is where gas exchange takes place between the air in the alveoli and the blood in capillaries surrounding them.
• The respiratory system protects itself from potentially harmful substances in the air by the mucociliary escalator. This includes mucus-producing cells, which trap particles and pathogens in the incoming air. It also includes tiny hair-like cilia that continually move to sweep the mucus and trapped debris away from the lungs and toward the outside of the body.
• The level of carbon dioxide in the blood is monitored by cells in the brain. If the level becomes too high, it triggers a faster rate of breathing, which lowers the level to the normal range. The opposite occurs if the level becomes too low. The respiratory system exchanges gases with the outside air, but it needs the cardiovascular system to carry the gases to and from cells throughout the body.
• Breathing is one of the few vital bodily functions that can be controlled consciously as well as unconsciously. Conscious control of breathing is common in many activities, including swimming and singing. However, there are limits on the conscious control of breathing. If you try to hold your breath, for example, you will soon have an irrepressible urge to breathe.
• Unconscious breathing is controlled by respiratory centers in the medulla and pons of the brainstem. They respond to variations in blood pH by either increasing or decreasing the rate of breathing as needed to return the pH level to the normal range.
• Nasal breathing is generally considered to be superior to mouth breathing because it does a better job of filtering, warming, and moistening incoming air. It also results in slower emptying of the lungs, which allows more oxygen to be extracted from the air.
• Gas exchange in the lungs takes place in alveoli. The pulmonary artery carries deoxygenated blood from the heart to the lungs, where it travels through pulmonary capillaries, picking up oxygen, and releasing carbon dioxide. The oxygenated blood then leaves the lungs through pulmonary veins.
• Gas exchange occurs by diffusion across cell membranes. Gas molecules naturally move down a concentration gradient from an area of higher concentration to an area of lower concentration. This is a passive process that requires no energy.
• Gas exchange by diffusion depends on the large surface area provided by the hundreds of millions of alveoli in the lungs. It also depends on a steep concentration gradient for oxygen and carbon dioxide. This gradient is maintained by continuous blood flow and constant breathing.
• Asthma is a chronic inflammatory disease of the airways in the lungs, in which the airways periodically become inflamed. This causes swelling and narrowing of the airways, often with excessive mucus production, leading to difficulty breathing and other symptoms. Asthma is thought to be caused by a combination of genetic and environmental factors. Asthma attacks are triggered by allergens, air pollution, or other factors.
• Pneumonia is a common inflammatory disease of the respiratory tract in which inflammation affects primarily the alveoli, which become filled with fluid that inhibits gas exchange. Most cases of pneumonia are caused by viral or bacterial infections. Vaccines are available to prevent pneumonia; treatment often includes prescription antibiotics.
• Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by chronic poor airflow, which causes shortness of breath and a productive cough. It is caused most often by tobacco smoking, which leads to the breakdown of connective tissues in the lungs. Alveoli are reduced in number and elasticity, making it impossible to fully exhale air from the lungs. There is no cure for COPD, but stopping smoking may reduce the rate at which COPD worsens.
• Lung cancer is a malignant tumor characterized by uncontrolled cell growth in tissues of the lung. It results from accumulated DNA damage, most often caused by tobacco smoking. Lung cancer is typically diagnosed late, so most cases cannot be cured. It may be treated with surgery, chemotherapy, and/or radiation therapy.
• The major health risk of smoking is cancer of the lungs. Smoking also increases the risk of many other types of cancer. Tobacco smoke contains dozens of chemicals that are known carcinogens.
• Smoking is the primary cause of COPD. Chemicals such as carbon monoxide and cyanide in tobacco smoke reduce the elasticity of alveoli so the lungs can no longer fully exhale air.
• Smoking damages the cardiovascular system and increases the risk of high blood pressure, blood clots, heart attack, and stroke. Smoking also has a negative impact on levels of blood lipids.
• A wide diversity of additional adverse health effects are attributable to smoking, such as erectile dysfunction, female infertility, and slow wound healing.

Chapter Summary Review

• Describe the relationship between the bronchi, secondary bronchi, tertiary bronchi, and bronchioles.
• Deoxygenated and oxygenated blood both travel to the lungs. Describe what happens to each there.
• True or False. There are radioactive isotopes in cigarette smoke.
• True or False. The right and left lungs are identical in structure.
• Explain the difference between ventilation and gas exchange.
• Why does this happen?
• Which way do oxygen and carbon dioxide flow during the gas exchange between the blood and the body’s cells?
• Why does the body require oxygen and give off carbon dioxide as a waste product?
• True or False. Conduction refers to the movement of gases across cell membranes.
• True or False. Gas exchange does not require energy.
• What do coughing and sneezing have in common?
• phlegmociliary
• mucociliary
• mucoflagellar
• surfactociliary
• Why can COPD cause there to be too much carbon dioxide in the blood?
• What does this do to the blood pH?
• How does the body respond to this change in blood pH?
• Alveoli become inflamed and fill with fluid
• Can be caused by exposure to inhaled carcinogens
• There is a reduction in the number of alveoli
• Airways periodically narrow and fill with mucus
• True or False. Pneumonia can be caused by fungi.
• True or False. The diaphragm contracts during exhalation.
• What are three different types of things that can enter the respiratory system and cause illness or injury? Describe the negative health effects of each in your answer.
• Where are the respiratory centers of the brain located? What is the main function of the respiratory centers of the brain?
• Smoking increases the risk of getting influenza, commonly known as the flu. Explain why this could lead to a greater risk of getting pneumonia.
• If people had a gene that caused them to get asthma, could changes to their environment (such as more frequent cleaning) help their asthma? Why or why not?
• The largest bronchial tube
• An area of the brain that increases breathing rate
• A medication that opens constricted airways
• A medication that clears the nasal cavity
• Explain why nasal breathing generally stops particles from entering the body at an earlier stage than mouth breathing.

Attributions

• Enjoying the Humidifier by Eden, Janine and Jim, CC BY 2.0 via Flickr.com
• Acute Bronchitis by National Heart Lung and Blood Institute, public domain via Wikimedia Commons
• Text adapted from Human Biolog y by CK-12 licensed CC BY-NC 3.0

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Chapter 13 Answers: Respiratory System

13.2  structure and function of the respiratory system: review questions and answers.

• Self-marking
• What is respiration, as carried out by the respiratory system? Name the two subsidiary processes it involves. Respiration is the process in which oxygen moves from the outside air into the body and carbon dioxide and other waste gases move from inside the body into the outside air. It involves ventilation and gas exchange.
• Describe the respiratory tract. The respiratory tract is a continuous system of passages that carry air into and out of the body. It has two major divisions: the upper respiratory tract and the lower respiratory tract.
• Identify the organs of the upper respiratory tract. What are their functions?  The organs of the upper respiratory tract are the nasal cavity, pharynx, and larynx. All of these organs are involved in conduction, or the movement of air into and out of the body. Incoming air is also cleaned, humidified, and warmed as it passes through the organs of the upper respiratory tract. The larynx contains the vocal cords, which have the function of producing vocal sounds.
• List the organs of the lower respiratory tract. Which organs are involved only in conduction? The organs of the lower respiratory tract are trachea, bronchi and bronchioles, and the lungs. The trachea, bronchi, and bronchioles are involved in conduction.
• Where does gas exchange take place? Gas exchange takes place only in the lungs. Lung tissue consists mainly of tiny air sacs called alveoli, which is where gas exchange takes place between air in the alveoli and the blood in capillaries surrounding them.
• How does the respiratory system protect itself from potentially harmful substances in the air? The respiratory system protects itself from potentially harmful substances in the air by the mucociliary escalator. This includes mucus-producing cells, which trap particles and pathogens in incoming air. It also includes tiny hair-like cilia that continually move to sweep the mucus and trapped debris away from the lungs and toward the outside of the body.
• Explain how the rate of breathing is controlled. The rate of breathing is controlled by the nervous system. The level of carbon dioxide in the blood is monitored by cells in the brain. If the level becomes too high, it triggers a faster rate of breathing, which lowers the level to the normal range. The opposite occurs if the level becomes too low.
• Why does the respiratory system need the cardiovascular system to help it perform its main function of gas exchange?  The respiratory system exchanges gases with the outside air, but it needs the cardiovascular system to carry the gases to and from cells throughout the body.
• Describe two ways in which the body prevents food from entering the lungs. Answers may vary. Sample answer:  The epiglottis at the entrance to the larynx closes when swallowing occurs, preventing food from entering the larynx and going deeper into the respiratory tract towards the lungs. Also, if food does start to enter the larynx, it irritates it, which triggers a cough reflex. This usually expels the food out of the larynx and into the throat.
• What is the relationship between respiration and cellular respiration? Answers may vary. Sample answer:  Cellular respiration is the intracellular process by which cells produce energy. Aerobic cellular respiration requires oxygen to “burn” glucose for energy and produces carbon dioxide as a waste product. Respiration refers to the process by which the body obtains the oxygen necessary for cellular respiration and releases the carbon dioxide waste out to the atmosphere.

13.3  Breathing: Review Questions and Answers

• Define breathing. Breathing, or ventilation, is the two-step process of drawing air into the lungs (inhaling) and letting air out of the lungs (exhaling).
• Give examples of activities in which breathing is consciously controlled. Answers may vary. Sample answer: Breathing is consciously controlled in swimming, speech training, singing, playing many musical instruments, and yoga.
• Explain how unconscious breathing is controlled. Unconscious breathing is controlled by respiratory centres in the medulla and pons of the brainstem. These centres monitor and respond to variations in blood pH by either increasing or decreasing the rate of breathing as needed to return the pH level to the normal range.
• Young children sometimes threaten to hold their breath until they get something they want. Why is this an idle threat? This is an idle threat because when they try to hold their breath, they will soon have an irrepressible urge to breathe.
• Why is nasal breathing generally considered superior to mouth breathing? Nasal breathing is generally considered to be superior to mouth breathing because it does a better job of filtering, warming, and moistening incoming air. It also results in slower emptying of the lungs, which allows more oxygen to be extracted from the air.
• Give one example of a situation that would cause blood pH to rise excessively. Explain why this occurs. Answers will vary. Sample answer:  During an asthma attack, involuntary hyperventilation can occur. This causes the loss of too much carbon dioxide from the body due to the rapid rate of breathing. Carbon dioxide decreases blood pH, so the loss of too much carbon dioxide will cause blood pH to rise excessively.

13.4  Gas Exchange: Review Questions and Answers

• What is gas exchange? Gas exchange is the biological process through which gases are transferred across cell membranes to either enter or leave the blood.
• Summarize the flow of blood into and out of the lungs for gas exchange. The pulmonary artery carries deoxygenated blood from the heart to the lungs, where it travels through pulmonary capillaries, picking up oxygen and releasing carbon dioxide. The oxygenated blood then leaves the lungs through pulmonary veins, which carry it to the heart to be pumped to cells throughout the body.
• Describe the mechanism by which gas exchange takes place.  Gas exchange takes place by diffusion across cell membranes. Gas molecules naturally move down a concentration gradient from an area of higher concentration to an area of lower concentration. This is a passive process that requires no energy.
• Identify the two main factors upon which gas exchange by diffusion depends. Gas exchange by diffusion depends on the large surface area provided by the hundreds of millions of alveoli in the lungs. It also depends on a steep concentration gradient for oxygen and carbon dioxide. This gradient is maintained by continuous blood flow and constant breathing.
• If the concentration of oxygen were higher inside of a cell than outside of it, which way would the oxygen flow? Explain your answer. The oxygen would flow out of the cell, because gases diffuse from an area of higher concentration to an area of lower concentration across a cell membrane.
• Why is it important that the walls of the alveoli are only one cell thick? Answers may vary. Sample answer:  The walls of the alveoli being only one cell thick makes gas exchange much easier and more efficient because the gases only have to pass across a thin membrane to get to and from the bloodstream.
• There are so many alveoli because a large surface area is needed for the diffusion necessary for gas exchange.

13.5  Disorders of the Respiratory System: Review Questions and Answers

• How can asthma attacks be prevented? How can symptoms of asthma attacks be controlled? Ways to prevent asthma attacks include taking long-term control medications such as corticosteroids and avoiding things that trigger asthma attacks. Symptoms can be controlled by the use of bronchodilators.
• How can pneumonia be prevented? How is it treated? Pneumonia can often be prevented with vaccines. Treatment of pneumonia depends on its cause. In cases of bacterial pneumonia, it generally includes prescription antibiotics. Treatment may also include hospitalization and supplemental oxygen.
• What is the difference between primary and secondary lung cancer? What is the major cause of primary lung cancer? Discuss lung cancer as a cause of death. How is lung cancer treated? Primary lung cancer is a malignant tumor that originates in lung tissue. Secondary lung cancer is a malignant tumor in the lung that originates elsewhere in the body and spreads to the lung. Lung cancer is the most common cause of cancer-related death in men and the second most common cause in women. Lung cancer is so deadly in part because it is generally diagnosed too late to be cured. Lung cancer typically is treated with surgery, chemotherapy, and/or radiation therapy.
• What is the difference between how COPD and pneumonia affect the alveoli? COPD involves the breakdown of the walls of the alveoli, reducing their number and making them less elastic. Pneumonia involves fluid build up within the alveoli.

13.6  Smoking and Health: Review Questions and Answers

• Create a pamphlet aimed at informing teenagers about the dangers of smoking.  Include information about numbers of deaths associated with smoking, life expectancy of smokers, and long term healthy effects of smoking and exposure to second-hand smoke.  Include a section on the chemicals present in tobacco smoke and e-cigarettes and some of the adverse affects associated with these chemicals.
• What smoking-related factors determine how smoking affects a smoker’s health? The detrimental health effects of smoking depend on the number of years that a person smokes and how much the person smokes.
• What are the two sources of secondhand cigarette smoke? How does exposure to secondhand smoke affect non-smokers? The two sources of secondhand cigarette smoke are smoke that comes directly from burning tobacco and smoke that comes from the lungs of smokers when they exhale. Exposure to secondhand smoke affects non-smokers in much the same way as smokers are affected by smoking. For example, non-smokers exposed to secondhand smoke have as much as a 30 per cent increase in their risk of lung cancer and heart disease.
• Why is it so difficult for smokers to quit the habit? How is their health likely to be affected by quitting? It is so difficult for smokers to quit the habit because tobacco smoke contains nicotine, which is a highly addictive psychoactive drug. After quitting, a former smoker’s risks of smoking-related diseases and death soon start to fall.
• Why does smoking cause cancer? List five types of cancer that are significantly more likely in smokers than non-smokers. Smoking causes cancer because tobacco smoke contains dozens of chemicals that have been proven to be carcinogens. Many of these chemicals bind to DNA in a smoker’s cells and may either kill the cells or cause mutations. If the mutations inhibit programmed cell death, the cells can survive to become cancer cells. Answers may vary. Sample answer:  Five types of cancer that are significantly more likely in smokers than non-smokers are cancers of the lung, kidney, larynx, mouth, and throat.
• Explain how smoking causes COPD. Chemicals such as carbon monoxide and cyanide in tobacco smoke reduce the elasticity of alveoli, leading to COPD. The carcinogen in tobacco smoke called acrolein contributes to the chronic inflammation that is also present in COPD. COPD is almost completely preventable by not smoking and by avoiding exposure to secondhand smoke.
• Do you think e-cigarettes can be addictive? Explain your reasoning. Answers may vary. Sample answer:  I think e-cigarettes can be addictive because they contain nicotine, which is a highly addictive drug.

13.7  Case Study Conclusion and Chapter Summary: Review Questions and Answers

• Describe the relationship between the bronchi, secondary bronchi, tertiary bronchi, and bronchioles. The bronchi are the two tubes of the airway that branch off from the trachea. The secondary bronchi branch off from the bronchi, the tertiary bronchi branch off from the secondary bronchi, and the bronchioles branch off from the tertiary bronchi. These passages get increasingly smaller as they branch off.
• Deoxygenated and oxygenated blood both travel to the lungs. Describe what happens to each there Deoxygenated blood picks up oxygen in the lungs via gas exchange and then transports it to the heart and out to the body’s cells. Oxygenated blood is used by the cells of the lungs to carry out aerobic cellular respiration to provide energy for its functions.
• Explain the difference between ventilation and gas exchange. Ventilation is also called breathing. It is the physical process of moving air to and from the lungs. Gas exchange refers to the biochemical process in which oxygen diffuses out of the air and into the blood while carbon dioxide and other waste gases diffuse out of the blood and into the air.
• Which way do oxygen and carbon dioxide flow during gas exchange in the lungs, and why? Which way do oxygen and carbon dioxide flow during gas exchange between the blood and the body’s cells, and why?  In the lungs, oxygen flows from the air inside the alveoli into the blood and carbon dioxide flows from the blood to the air inside the alveoli. This is because the oxygen concentration is higher in the air inside the alveoli and the carbon dioxide concentration is higher in the blood, and gases naturally diffuse from an area of higher concentration to an area of lower concentration. Oxygen flows from the blood to the body’s cells, and carbon dioxide flows from the body’s cells into the blood. This is because the oxygen concentration is higher in the blood and the carbon dioxide concentration is higher in the body’s cells, and gases naturally diffuse from an area of higher concentration to an area of lower concentration.
• Why does the body require oxygen, and why does it emit carbon dioxide as a waste product?  The body’s cells use oxygen and produce carbon dioxide as waste in the process called aerobic cellular respiration. This process provides energy needed for the body’s functions by “burning” glucose.
• What do coughing and sneezing have in common? Answers may vary. Sample answer:  Coughing and sneezing are involuntary responses that occur when the nerves in the airways or nasal passages are irritated. They are forceful responses that expel mucus and debris out of the respiratory system to keep the airways clear and to keep harmful particles out.
• How does COPD cause there to be too much carbon dioxide in the blood? Answers may vary. Sample answer:  COPD hampers gas exchange because the walls of the alveoli are damaged. Therefore, oxygen intake and carbon dioxide removal are impaired, which can lead to a build up of carbon dioxide in the blood.
• What does this do to the blood pH? Too much carbon dioxide lowers blood pH.
• How does the body respond to this change in blood pH? Answers may vary. Sample answer:  The respiratory centres in the brain detect the drop in pH and cause the body to respond by increasing the rate of breathing.
• What are three different types of things that can enter the respiratory system and cause illness or injury? Describe the negative health effects of each in your answer.   Answers will vary. Sample answer:  Foreign objects such as food can get lodged in the respiratory system and cause choking. Pathogens such as bacteria and viruses can enter the respiratory system and cause infectious diseases such as a cold, flu, or pneumonia. Carcinogenic chemicals, such as those found in tobacco smoke, can enter the respiratory system and cause cancer.
• Where are the respiratory centres of the brain located? What is the main function of the respiratory centres of the brain? The brainstem, specifically the medulla oblongata and the pons. The main function of the respiratory centres of the brain is to regulate the rate of breathing.
• Smoking increases the risk of getting influenza, commonly known as the flu. Explain why this could lead to a greater risk of pneumonia. Pneumonia often develops as a secondary infection after an upper respiratory infection such as the flu. Therefore, a higher risk of getting the flu also raises the risk of getting pneumonia.
• If a person has a gene that caused them to get asthma, could changes to their environment (such as more frequent cleaning) help their asthma? Why or why not? Answers may vary. Sample answer:  Even if a person has asthma due to their genetics, asthma attacks can be triggered by substances in the environment such as pet dander, dust mites, and mold. Therefore, more frequent cleaning may help lessen the frequency or severity of their asthma attacks.
• Explain why nasal breathing generally stops particles from entering the body at an earlier stage than mouth breathing does. Answers may vary. Sample answer:  The nasal passages are lined with hairs that more effectively trap particles when you inhale, as compared to the mouth.

Human Biology Copyright © 2020 by Christine Miller is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License , except where otherwise noted.

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