Respiratory System Quiz

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Questions and Answers

What is the main function of the mucus secreted by specialized cells in the paranasal sinuses?

To enhance taste during swallowing

To block airflow to the lungs

To warm and humidify inhaled air (correct)

To increase the speed of ciliary movement

What primarily causes sinusitis according to the content?

Bacterial infections

Pollution and smoke exposure

Viruses and inhaled allergens (correct)

Fungal infections

Which of the following statements about epiglottitis is true?

It can result from certain infections and is a medical emergency. (correct)

It primarily affects the paranasal sinuses.

It is a common non-emergency condition.

It is caused by exposure to allergens only.

What role do the cilia in the upper respiratory tract play?

Sweeping debris and mucus toward the nose and mouth Signup and view all the answers

What is the main impact of sinus congestion?

It creates pressure on surrounding structures. Signup and view all the answers

Which symptom is commonly associated with respiratory infections?

Stridor Signup and view all the answers

What is laryngitis primarily characterized by?

Voice loss Signup and view all the answers

What condition is defined by inflammation of the bronchi and/or bronchioles?

Bronchitis Signup and view all the answers

Who is most likely to have a different normal microbiota profile in the respiratory tract?

Individuals with cystic fibrosis Signup and view all the answers

What term describes the inflammation and swelling of the trachea?

Tracheitis Signup and view all the answers

What role do resident microbiota typically play in the respiratory tract?

Competing with pathogens Signup and view all the answers

What is pneumonia characterized by?

Inflammation of the alveoli Signup and view all the answers

What type of genome does SARS-CoV-2 possess?

Single-stranded RNA genome Signup and view all the answers

How does SARS-CoV-2 primarily spread?

Via respiratory droplets and aerosols Signup and view all the answers

What is the main cause of death in patients with COVID-19?

Sudden reduction in blood oxygenation Signup and view all the answers

SARS-CoV-2 variants are classified based on what criteria?

Potential impact on public health Signup and view all the answers

What distinguishes a new viral strain from a viral variant?

Alteration of viral functions Signup and view all the answers

Which type of SARS-CoV-2 variant is associated with reduced efficacy of diagnostics and vaccines?

Variants of Concern Signup and view all the answers

What is a key characteristic of Variants of High Consequence?

Significant reduction in efficacy of existing diagnostics and vaccines Signup and view all the answers

What timeframe is noted for symptom development after SARS-CoV-2 exposure?

2 to 14 days Signup and view all the answers

Which enzyme is encoded by the genome of SARS-CoV-2?

RNA-dependent RNA polymerase Signup and view all the answers

What is a common clinical feature of typical pneumonia?

Shortness of breath Signup and view all the answers

Which symptom is typically associated with atypical pneumonia?

Cough with little or no sputum Signup and view all the answers

Which of the following is a common finding in the chest X-ray of typical pneumonia?

Opaque white area in at least one lung lobe Signup and view all the answers

What type of bacteria are typically revealed in a sputum culture for pneumonia?

Gram-positive or Gram-negative bacteria Signup and view all the answers

How is the onset of symptoms different in atypical pneumonia compared to typical pneumonia?

Onset is usually more gradual for atypical pneumonia Signup and view all the answers

What is a typical prevalence ratio of pneumonia cases?

4 out of 5 pneumonia cases are typical Signup and view all the answers

What respiratory examination finding is likely in typical pneumonia?

Crackling sound (or rales) observed Signup and view all the answers

Which of the following better describes the sputum associated with typical pneumonia?

Cough with sputum (productive cough) Signup and view all the answers

Which of the following features differentiates atypical pneumonia?

Community-acquired infections Signup and view all the answers

Study Notes

Microbiology: Basic and Clinical Principles - Chapter 16

Chapter 16 covers Respiratory System Infections.
The chapter was presented by Janet Dowding, Ph.D.
The Case of the Suffering Spelunker is a clinical case study.
Students should describe the parts of the upper and lower divisions of the human respiratory system after reading the chapter.

Overview of the Respiratory System

The respiratory system is responsible for bringing oxygen into the body and removing carbon dioxide.
It's the most common portal of entry for microbes.
The impact and destination of microbes varies based on the pathogen.
The respiratory tract is divided into upper and lower respiratory tracts.
The upper respiratory tract includes the mouth, nasal passages, paranasal sinuses, pharynx, and epiglottis, which warm, humidify, and filter inhaled air and trap microbes and debris via cilia.
The lower respiratory tract consists of the larynx, trachea, bronchi, bronchioles, lungs, and alveoli, directing air to the lungs, the site of gas exchange.
The information can be found in the Mastering Microbiology Study Area.

The Respiratory System is the Most Common Portal of Entry for Microbes

The respiratory system brings oxygen into the body and removes carbon dioxide.
It's the primary route of entry for microorganisms.
The specific effect and location of the microbe depend on the pathogen.

Paranasal sinuses: Four pairs of hollow cavities lined by mucous membranes, specialized cells and glands secrete mucus to warm and humidify inhaled air. Cilia sweep debris and mucus toward the nose and mouth.
Sinusitis: Inflammation of the sinuses can be caused by infectious agents or inhaled allergens. Drainage of mucus is blocked, causing buildup in hollow sinuses, which causes pressure on surrounding structures. Trapped mucus can lead to bacterial growth.
The majority of sinusitis cases are caused by viruses, not bacteria. Antibiotics do not usually treat sinusitis.
Pharynx: The end of the upper respiratory tract. It acts as a gatekeeper between the respiratory and digestive systems.
Pharyngitis: Inflammation of the pharynx. Viral, bacterial, or allergic causes are possible.
Epiglottis: A cartilage structure that seals off the airway during swallowing, preventing food and drinks from entering the lungs.
Epiglottitis: Inflammation and swelling of the epiglottis, possibly blocking the airway. Haemophilus influenzae type b is a common cause.

Clinical Vocabulary

Sinusitis: Inflammation and swelling of the sinus membranes.
Pharyngitis: Inflammation of the pharynx (throat).
Epiglottitis: Inflammation and swelling of the epiglottis, potentially blocking the airway.

Mucociliary escalator: Ciliated mucous membranes in the lower respiratory tract that trap inhaled debris and sweep it toward the mouth to prevent it from entering the lungs.
Alveolar macrophages: Cells residing in the alveoli (air sacs) of the lungs that clear out debris and pathogens.

Inhaled Allergens and Microbes

Inhaled allergens and microbes can cause inflammation of lower respiratory tract tissues.
Laryngitis: Inflammation of the larynx (voice box). Can cause temporary voice loss due to swelling in the vocal cords.
Tracheitis: Inflammation of the trachea.
Bronchitis: Inflammation of the bronchi and/or bronchioles
Croup: Combined inflammation of the larynx, trachea, bronchi, and bronchioles, often caused by viruses. Characteristic is a barking cough and respiratory stridor.
Pneumonia: Inflammation of the lung tissue. Can upset the delicate oxygen balance, potentially becoming life-threatening.
Signs and symptoms like coughing, stridor, dyspnea (shortness of breath), fatigue, sneezing, sore throat, and fever are often seen in respiratory tract infections.

Clinical Vocabulary (Respiratory Tract Infections)

Laryngitis: Inflammation and swelling of the larynx; can cause voice loss.
Tracheitis: Inflammation and swelling of the trachea.
Bronchitis: Inflammation and swelling of the bronchi and/or bronchioles.
Croup: Inflammation of the larynx, trachea, bronchi, and bronchioles (combined).
Stridor: Wheezing or loud breathing associated with a blocked or narrowed airway.
Pneumonia: Inflammation of the alveoli (air sacs in the lungs) where gas exchange occurs.
Dyspnea: Shortness of breath.

Respiratory Tract Microbiome

Many microorganisms colonize the respiratory tract.
Healthy lungs were previously thought to be sterile.
Resident microbiota are typically more helpful than harmful, competing with pathogens and secreting antimicrobial peptides to limit the growth of would-be pathogens.
Normal microbiota profiles vary between individuals and those with underlying health issues like asthma, COPD, cystic fibrosis, and lung cancer.
Healthy microbiome displays high diversity of species, mainly dominated by bacteria from the phyla Bacteroides, Firmicutes, Actinobacteria, Proteobacteria, and Fusobacteria (found in different parts of the tract).
Detailed profiles of microbiota are in the Mastering Microbiology Study Area.

Viral Infections of the Respiratory System

Many viruses can infect the respiratory tract.
Common cold symptoms overlap with other viral illnesses.
Common cold severity and prognosis depend on the infectious agent and patient factors like age and general health.

Influenza (“the flu”)

Influenza ("the flu") has symptoms resembling a severe cold
Influenza mechanism involves binding to ciliated cells in the upper respiratory tract and sometimes impacting the lungs directly.
Complications can be deadly in those with pre-existing conditions.
Disease and death rates vary annually depending on circulating influenza strains (outbreaks or pandemics).
There are three influenza virus types, A, B, and C with type A being most common, causing outbreaks.
Influenza has virulence factors hemagglutinin (HA) and neuraminidase (NA) that are glycoprotein spikes.
HA allows the virus to attach and invade cells, while NA helps new viral particles leave the cell.
HA and NA subtypes are a basis for naming subtypes and classifying strains; multiple subtypes exist, and new strains emerge due to the virus's ability to mutate and genetically recombine its RNA.
Vaccines are created annually based on predicted circulating strains to prevent and mitigate outbreaks.
Inactivated and live-attenuated formulations are among the vaccines recommended.

Seasonal Outbreaks Versus Worldwide Pandemics

Antigenic drift (random mutations): Causes minor changes to HA and NA spikes, enabling the virus to evade the immune system.
Antigenic shift (major genetic change): Causes major alterations in viral antigens, allowing for pandemics.
In the 1918 pandemic (Spanish flu), cytokine storms leading to out-of-control immune responses are implicated in the high mortality rates, primarily in 15–34-year-olds.

Clinical Vocabulary (Respiratory Tract Infections) (continued)

Exudate: Pus-like or clear fluid discharge from inflamed tissues.
Paroxysm: Sudden, violent attack (e.g., coughing).
Convalescent: Recovering but not completely better.
Latent infection: Infectious agent is present but not causing symptoms until conditions are right.
Induration: Hardening of tissue caused by inflammation.
Bacteremia: Presence of bacteria in the blood.

Cold, Otitis Media

Common cold is the most frequent respiratory infection, caused by various viruses (over ~200 genetic types).
Serovars of rhinoviruses and coronaviruses cause 60–80% of all colds.
Cold viruses are highly contagious, spreading via personal contact, respiratory droplets, and fomites.
Symptoms of colds include sore throat, runny nose, cough, sneezing, fatigue, body aches, low-grade fever (common in children), and thickened, discolored mucus.
Most colds are self-limiting, though secondary bacterial infections are possible (as they are secondary infections complicating viral ones).
Adults typically develop ~3 colds per year, and children often develop ~6 colds per year.
Cold illnesses can lead to sinus, ear, or lower respiratory tract infections. Antibiotics are usually ineffective in most cases.

Otitis Media

Otitis media is mainly caused by Streptococcus pneumoniae, Moraxella catarrhalis, and non-typable Haemophilus influenzae.
During a cold, inflamed membranes can cause mucus accumulation, creating a growth environment for bacteria.
Eustachian tubes connecting the middle ear to the pharynx can become inflamed with a cold, hindering mucus drainage and leading to bacterial infections.
Children are more susceptible due to shorter and narrower eustachian tubes, resulting in inefficient drainage.
Tubes may be surgically inserted to help with drainage.

Streptococcus Pyogenes

Streptococcus pyogenes is a gram-positive cocci bacterium often present in the upper respiratory tract and skin.
Some strains cause diseases like endocarditis, pharyngitis, meningitis, genitourinary infections, sepsis, dental caries, skin infections, and pneumonia.
Streptococcal pharyngitis (strep throat) is an acute pharyngitis resulting in a sore throat, swollen lymph nodes, low-grade fever, exudate, and absence of cough.
Complications following strep throat include otitis, sinusitis, and pneumonia.
Rapid antigen detection and bacterial cultures are ways to diagnose strep throat.
Penicillin is a common effective treatment for strep throat.

Scarlet Fever

Scarlet fever is caused by the lysogenized S. pyogenes strain acquiring the ability to produce erythrogenic toxins.
This leads to <10% of strep throat cases developing scarlet fever; this is more common in children under 10 years old
Symptoms of scarlet fever include a red, sandpaper-like rash, often starting on the face and neck and spreading downwards, and a strawberry-like red tongue.

Autoimmune Complications of S. pyogenes

Certain M proteins in S. pyogenes closely resemble proteins in the heart valves, kidneys, and joints.
These M proteins stimulate production of antibodies that also react with human tissue.
Rheumatic heart disease is a primary complication brought on by these cross-reacting antibodies.

Corynebacterium Diphtheriae and Diphtheria

Corynebacterium diphtheriae is a gram-positive rod.
Diphtheria commonly affects children under five years old.
Diphtheria is spread by respiratory droplets.
Initial signs are cold-like symptoms, sore throat, low-grade fever, and hoarseness.
The characteristic "bull neck" pseudomembrane develops in the upper airways after a few days
Severe complications, including coma and death, can occur from the strains producing potent exotoxins that enter the bloodstream and affect protein synthesis; untreated cases carry a high risk of death.
Treatments include antibiotics and antitoxin from the vaccine.

Pertussis (Whooping Cough)

Pertussis is an infection of the respiratory tract caused by Bordetella pertussis, a gram-negative bacterium.
Pertussis has three distinct stages: catarrhal (cold-like symptoms), paroxysmal (severe coughing), and convalescent (less frequent coughing).
Complications include vomiting, fractured ribs, and loss of bladder control (more severe in young children and babies), and potentially bleeding behind the eyes and in the brain.
A booster vaccine (Tdap) is recommended and is part of routine childhood vaccinations to decrease the risk of recurrence.

Tuberculosis (TB)

Tuberculosis (TB) is a disease caused by Mycobacterium tuberculosis, an acid-fast rod.
TB is transmitted from person to person via respiratory droplets.
In most affected cases, people have latent TB, which is asymptomatic and not contagious.
Active TB progression involves bloody sputum (bloody-tinged), fever, night sweats, fatigue, and weight loss.
The BCG vaccine is routinely given to children in various countries, while TB screenings and molecular diagnostics are used in areas with limited routine vaccination.

Antibiotic Resistance in TB

Multidrug-resistant (MDR) TB and extensively drug-resistant (XDR) TB strains are resistant to first-line defense drugs.
MDR TB is commonly found across various countries, increasing from 2018 to 2019 globally by ~10%.
MDR TB has a ~57% chance of being cured.
XDR TB carries a ~39% chance of being cured.
Active TB caused by MDR or XDR strains is treated for around two years with costly, side-effect prone medication; cure rates are lower.

Pneumonia

Pneumonia is an inflammation of the lower respiratory tract, particularly the alveoli; several types of organisms cause pneumonia.
Common causes include bacteria and viruses.
Healthcare-acquired infections (HAIs) frequently include pneumonia types like hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP).
Community-acquired pneumonia (CAP) is pneumonia developing outside healthcare facilities.
Typical pneumonia (e.g., pneumococcal pneumonia caused by S. pneumoniae) often presents with consolidation on X-rays.
Atypical pneumonia (e.g., those caused by Chlamydia pneumoniae, Mycoplasma pneumoniae, Legionella pneumophila, or Francisella tularensis) lack this consolidation feature.
Other microorganisms are also causative agents of pneumonia (such as viruses or parasites).

Haemophilus influenzae (Hib) Pneumonia.

Haemophilus influenzae (Hib) pneumonia is caused by the gram-negative bacteria H. influenzae.
Specific typable strains are based on the analysis of polysaccharide capsules (6 types a-f); others lack them.
Hib does not cause influenza but can cause epiglottitis, cellulitis, pneumonia, and meningitis and most commonly infects individuals below age six.
Prevention is with the five licensed vaccines in the United States successfully reducing occurrences to less than ~50 cases each year.

Atypical Pneumonia, Part 1

Mycoplasma pneumoniae (walking pneumonia) is an infection caused by a gram-positive bacterium, the smallest self-replicating organism without a cell wall, living inside host cells
Mycoplasma pneumonia is the most frequent case of community-acquired pneumonia (~2 million cases each year), with about 100,000 requiring hospitalization.
The infection progresses slowly, and up to 20% of infections are asymptomatic.
Chlamydophila pneumoniae is another atypical pneumonia cause; it causes sinusitis, pneumonia, bronchitis, and pharyngitis and can be present during 2-5 million cases each year. Around ~500,000 require hospitalization, and symptoms can present as a sore throat progressing to coughing, lasting for up to six weeks.

Atypical Pneumonia, Part 2

Legionnaires' disease and Pontiac fever, two similar atypical pneumonia diseases, although distinct, both are caused by the Gram-negative bacterium Legionella pneumophilia.
Legionnaires' disease presents as high fever, cough, chest discomfort, and respiratory distress.
Pontiac fever has less severe symptoms, like a mild flu
The microorganisms that cause this disease tend to survive inside phagocytic cells and thus are resistant to several treatments.
Diagnostics often include cultures, antigen tests, PCR, and serology. They are treated with quinolones or macrolides.
Psittacosis or ornithosis, caused by Chlamydophila psittaci, the gram-negative bacterium, is usually spread through birds (particularly pet birds).
The causative organism commonly causes muscle aches and stiffness; untreated infections can trigger fever recurrences over multiple weeks and can be fatal in about ~10%~40% of cases.
Q fever is an atypical pneumonia caused by the Gram-negative bacterium Coxiella burnetii.
Q fever is characterized by flu-like symptoms that can be accompanied by pneumonia.
Q fever is transmitted from livestock (cattle, sheep) to people through ticks, airborne dust from feces, urine, or birthing products, or by eating unpasteurized milk products.
Tularemia, caused by Francisella tularensis, is a zoonotic disease with a broad host range.
The gram-negative bacterium has high infectivity and is transmitted via inhaling aerosols from animal matter or from direct handling of animals.

Fungal Respiratory Infections

Mycoses, fungal infections, are relatively rare in comparison to bacterial and viral infections of the respiratory tract, but they are increasing due to factors like increased urban development, deforestation, climate change, and an increased number of immunosuppressed people.
Some are endemic (only spread in specific geographic areas). Examples include blastomycosis.
Others are ubiquitous (spread in varied climates).
Many respiratory mycoses are contracted by inhaling the fungal spores.

Blastomycosis (Chicago Disease)

Blastomycosis (Chicago Disease) is caused by Blastomyces dermatitidis, a dimorphic endemic fungus.
This fungus is found in parts of the U.S. (Mississippi and Ohio River valleys, Great Lakes region, parts of Canada, Great Lakes and St. Lawrence Seaway).
It's transmitted via airborne conidia spores, generated by the fungi in the environment. Soil disturbances can increase exposure.
Disease progression involves the spores settling in the lungs, causing them to become yeast-like. Disseminated blastomycosis is a complication.
Antifungal treatments are used to address the infection.

Coccidioidomycosis (Valley Fever)

Coccidioidomycosis (Valley Fever) is caused by Coccidioides immitis and Coccidioides posadasii fungal species, endemic to the southwestern U.S., northern Mexico, and Central and South America.
Transmission is by inhalation of arthroconidia spores that disperse via wind.
Spores develop into spherules within the lungs and release endospores, initiating infections.
Common symptoms include fever, headache, cough, muscle aches, joint pain, and rash. Dissemination can occur in immune-compromised patients.
Treatment includes antifungal drugs like fluconazole, itraconazole, ketoconazole, or amphotericin B.

Histoplasmosis

Histoplasmosis is caused by Histoplasma capsulatum, a dimorphic fungus found worldwide, concentrated near river valleys, and particularly the Mississippi and Ohio River valleys in the United States.
The infection occurs via inhalation of macroconidia and microconidia spores present in soil enriched with bat and bird droppings.
Symptoms are rare in immunocompetent individuals.
Dissemination is more prevalent in immune-compromised individuals.
Treatment is with antifungal drugs (e.g., amphotericin B, fluconazole, itraconazole, ketoconazole).

Invasive Aspergillosis

Invasive aspergillosis is caused by Aspergillus species, mainly A. fumigatus, a common soil fungus found worldwide.
Inhalation of spores causes infection in immunocompromised patients.
Treatments are often multi-drug regimens including voriconazole, caspofungin, amphotericin B, and echinocandins.

Mucormycosis

Mucormycosis is caused by Rhizopus arrhizus, a fungus in soil enriched with rotting wood.
Transmission is by inhalation of spores.
Treatment varies depending on the patient's factors and the detection time.
Mortality rates are high without early treatment.

Pneumocystis Pneumonia (PCP)

Pneumocystis pneumonia (PCP) is caused by Pneumocystis jirovecii, which is not native to the soil.
Transmission is predominantly linked to asymptomatic human carriers, potentially via aerosolized transmission.
Untreated PCP is often fatal, and treatment is often ineffective without early assessment.
High-risk patients are often treated with low doses of trimethoprim-sulfamethoxazole.

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Test your knowledge on the human respiratory system, including the functions of mucus, the causes and symptoms of various illnesses, and the role of microbiota and viruses like SARS-CoV-2. This quiz covers essential concepts related to respiratory health and disease.