Respiratory System Practice Questions

Q: In an asthma attack, what causes the difficulty in exhaling air?

Increased airway resistance. ***Increased airway resistance*** - During an asthma attack, **bronchoconstriction**, **mucus plugs**, and **airway inflammation** narrow the bronchioles, significantly increasing the resistance to airflow. - This increased resistance makes it much harder for air to be expelled from the lungs, leading to the characteristic symptom of **difficulty exhaling**, and often trapping air within the lungs. *Decreased airway resistance* - **Decreased airway resistance** would make it easier to exhale, as there would be less impedance to airflow out of the lungs. - This is the opposite of what occurs in an asthma attack, where airways narrow and obstruct flow. *Decreased residual volume* - **Residual volume** is the amount of air remaining in the lungs after a maximal exhalation. In asthma, **air trapping** due to obstructed airways typically leads to an *increase* in residual volume, not a decrease. - A decreased residual volume would imply more efficient exhalation, which is not characteristic of an asthma attack. *Increased tidal volume* - **Tidal volume** is the amount of air inhaled or exhaled with each normal breath. During an asthma attack, while a person may try to breathe more deeply, the overall **efficiency of gas exchange** and air movement is compromised. - An uncontrolled asthma attack often leads to **shallow, rapid breathing** rather than an increased tidal volume, and the primary problem is difficulty moving air out, not the volume itself.

Q: A 60-year-old male with COPD is experiencing difficulty in breathing. Which alteration in lung compliance is most likely contributing to his symptoms?

Increased lung compliance due to alveolar destruction. ***Increased lung compliance due to alveolar destruction*** - In **COPD**, particularly **emphysema**, the destruction of alveolar walls and elastic fibers leads to a significant **loss of elastic recoil**. - This results in **increased lung compliance**, meaning the lungs are easier to inflate but struggle to expel air effectively, leading to air trapping and difficulty exhaling. *Increased airway resistance due to COPD* - While **increased airway resistance** is a hallmark of COPD, this option describes the resistance to airflow rather than lung compliance itself. - Airway resistance is primarily due to **bronchoconstriction**, mucus production, and airway wall thickening, which contribute to the overall breathing difficulty but are distinct from changes in compliance. *Normal lung compliance with isolated airway obstruction* - This option is incorrect because **COPD** is characterized by significant structural changes in the lungs, including alveolar destruction (emphysema) and inflammation of peripheral airways (chronic bronchitis), which directly impact lung compliance. - Therefore, lung compliance is typically **abnormal**, not normal, in COPD. *Decreased lung compliance due to restrictive lung disease* - **Decreased lung compliance** is characteristic of **restrictive lung diseases** (e.g., pulmonary fibrosis), where the lungs are stiff and difficult to inflate. - This is the opposite of what is seen in **COPD**, where the lungs become overly compliant due to the loss of elastic tissue.

Q: Which shift in the oxygen-hemoglobin dissociation curve facilitates oxygen unloading in the tissues?

Shift to the right. ***Shift to the right*** - A **rightward shift** of the oxygen-hemoglobin dissociation curve indicates that hemoglobin has a **decreased affinity for oxygen**. - This decreased affinity facilitates the **unloading of oxygen** from hemoglobin to the tissues where it is needed, especially in conditions of higher metabolic activity. *Shift to the left* - A **leftward shift** indicates an **increased affinity** of hemoglobin for oxygen, leading to **less oxygen unloading** in the tissues. - This shift is typically seen in conditions like **higher pH (alkalosis)**, lower temperature, and decreased 2,3-BPG. *No shift* - **No shift** would imply a constant affinity of hemoglobin for oxygen, which does not account for the physiological needs of oxygen delivery to metabolically active tissues. - The oxygen-hemoglobin dissociation curve **dynamically shifts** in response to metabolic demands. *Downward shift* - The term "downward shift" is **not a standard descriptor** for changes in the oxygen-hemoglobin dissociation curve and does not accurately represent a change in affinity. - Shifts are typically described as **right (decreased affinity)** or **left (increased affinity)**.

Q: A patient with severe asthma is found to have a decreased FEV1/FVC ratio. Which of the following best describes the underlying physiological change?

Increased airway resistance. ***Increased airway resistance*** - In **asthma**, bronchospasm and inflammation narrow the airways, substantially increasing the **resistance to airflow**. - This increased resistance preferentially impedes expiratory flow, leading to a disproportionate drop in **FEV1** relative to **FVC**. *Decreased lung compliance* - **Decreased lung compliance** typically characterizes **restrictive lung diseases**, where the lungs become stiff and difficult to inflate. - While severe asthma can result in some reduction in compliance due to hyperinflation, the primary physiological issue and cause of reduced FEV1/FVC is increased airway resistance, not decreased compliance. *Increased diffusion capacity* - **Increased diffusion capacity** (DLCO) is generally not seen in asthma; in fact, it can be normal or slightly reduced in severe cases due to air trapping. - Increased DLCO would suggest conditions like pulmonary hemorrhage or polycythemia, which are unrelated to the pathology of asthma. *Decreased pulmonary capillary pressure* - **Decreased pulmonary capillary pressure** is not a primary physiological feature of asthma. - Changes in pulmonary capillary pressure are more relevant to conditions affecting pulmonary circulation, such as heart failure or pulmonary hypertension, and do not directly explain a reduced FEV1/FVC ratio.

Q: A patient with chronic obstructive pulmonary disease (COPD) exhibits signs of respiratory acidosis. What is the primary cause?

Increased carbon dioxide retention. ***Increased carbon dioxide retention*** - In **COPD**, impaired gas exchange (due to airway obstruction and lung damage) leads to inefficient elimination of **carbon dioxide** from the body via exhalation. - The buildup of **CO2** in the blood, an acidic gas, results in a decrease in pH, causing **respiratory acidosis**. - This is the primary mechanism underlying respiratory acidosis in COPD patients. *Decreased carbon dioxide retention* - **Decreased CO2 retention** would imply efficient or excessive CO2 elimination, which would lead to **respiratory alkalosis**, the opposite of what is seen in this patient. - This scenario would be characterized by a **low PCO2**, not the elevated PCO2 found in respiratory acidosis. *Decreased bicarbonate reabsorption* - **Decreased bicarbonate reabsorption** by the kidneys would lead to a loss of bicarbonate, a base, from the body. - This would result in **metabolic acidosis**, not respiratory acidosis, and is not a primary respiratory issue. *Increased bicarbonate reabsorption* - **Increased bicarbonate reabsorption** is a compensatory mechanism by the kidneys in response to **respiratory acidosis**. - While it occurs to buffer the excess CO2, it is not the primary cause of the acidosis itself; rather, it is the body's attempt to correct it.

Q: A patient with diabetic ketoacidosis (DKA) presents with Kussmaul breathing. Which compensatory mechanism is he demonstrating?

Increased CO2 elimination. ***Increased CO2 elimination*** - Kussmaul breathing is a deep, rapid breathing pattern that represents the body's attempt to **compensate for metabolic acidosis** by expelling more carbon dioxide [1], [3]. - By increasing the rate and depth of breathing, the lungs remove more **acidic CO2**, thereby raising the blood pH [2]. *Increased CO2 retention* - **Increased CO2 retention** would worsen the patient's acidosis, as CO2 forms carbonic acid in the blood when combined with water, lowering the pH [4]. - This mechanism is characteristic of **respiratory acidosis**, not respiratory compensation for metabolic acidosis. *Decreased bicarbonate reabsorption* - **Bicarbonate reabsorption** primarily occurs in the kidneys and affects acid-base balance over a longer period, rather than being a rapid respiratory compensatory mechanism [2]. - **Decreased bicarbonate reabsorption** would lead to a loss of base, which would exacerbate acidosis, not compensate for it. *Increased bicarbonate excretion* - Similar to decreased bicarbonate reabsorption, **increased bicarbonate excretion** by the kidneys would result in a loss of base from the body. - This would further acidify the blood and is not a compensatory response for metabolic acidosis; instead, the kidneys would typically try to **conserve bicarbonate**.

Q: A 60-year-old man with chronic obstructive pulmonary disease (COPD) presents with hypercapnia. Which of the following physiological mechanisms is most likely contributing to his elevated CO2 levels?

Decreased alveolar ventilation. ***Decreased alveolar ventilation*** - In **COPD**, structural changes in the lungs (e.g., **emphysema**, chronic bronchitis) lead to **airway obstruction**; this reduces the amount of fresh air reaching the **alveoli**, leading to decreased gas exchange. - A reduction in **alveolar ventilation** directly impairs the body's ability to eliminate **carbon dioxide**, causing it to accumulate in the blood (**hypercapnia**). *Decreased metabolic CO2 production* - **Hypercapnia** signifies an excess of CO2 in the blood, which is usually due to inadequate elimination, not reduced production. - A decrease in **metabolic CO2 production** would lead to lower, not higher, CO2 levels, assuming normal ventilation. *Increased gas diffusion capacity* - **COPD** is characterized by alveolar damage (emphysema) that significantly **reduces the surface area** available for gas exchange, thus **decreasing**, not increasing, gas diffusion capacity. - Reduced diffusion capacity would primarily affect **oxygen uptake**, but it also contributes to overall impaired gas exchange efficiency, worsening CO2 retention. *Increased dead space ventilation* - While **COPD** can lead to an **increase in dead space ventilation** (ventilation of areas that do not participate in gas exchange, like severely damaged alveoli or large airways), this is a *consequence* or *type* of inefficient ventilation. - **Increased dead space ventilation** contributes to the overall reduction in *effective* alveolar ventilation, but the most direct cause of hypercapnia is the insufficient total amount of fresh air reaching the viable alveoli for gas exchange, hence "decreased alveolar ventilation" is a more encompassing and direct answer.

Q: Which process describes the transfer of oxygen from the lungs to the blood?

Diffusion. ***Diffusion*** - **Diffusion** is the primary mechanism by which **oxygen** moves from the **alveoli** in the lungs into the **pulmonary capillaries**. This movement occurs down a **concentration gradient** from an area of higher oxygen partial pressure (alveoli) to an area of lower oxygen partial pressure (blood). - Similarly, **carbon dioxide** moves from the blood into the **alveoli** by diffusion, following its own concentration gradient. *Filtration* - **Filtration** is a process by which fluids and solutes are forced through a membrane due to **hydrostatic pressure**, commonly seen in the **kidneys** for urine formation. - This mechanism is not involved in the direct transfer of gases between the lungs and the blood. *Reabsorption* - **Reabsorption** is the process by which filtered substances are taken back into the blood from the **renal tubules** in the kidneys. - It is not applicable to the gas exchange process in the respiratory system. *Active transport* - **Active transport** uses **cellular energy** (ATP) to move substances across a membrane against their **concentration gradient**. - Gas exchange in the lungs does not require active transport as it relies solely on **passive diffusion** down an electrochemical gradient.

Question 1

In evaluating spirometry results, explain why a patient with restrictive lung disease would have a normal or increased FEV1/FVC ratio.

Accepted Answer

Decreased lung compliance leads to a normal or increased FEV1/FVC ratio.

Answer

Increased airway resistance does not significantly affect the FEV1/FVC ratio in restrictive lung disease.

Answer

Increased residual volume is more relevant in obstructive conditions, not restrictive ones.

Answer

Decreased tidal volume does not directly affect the FEV1/FVC ratio.

Question 2

In an asthma attack, what causes the difficulty in exhaling air?

Accepted Answer

Increased airway resistance

Answer

Decreased airway resistance

Answer

Decreased residual volume

Answer

Increased tidal volume

Question 3

A 60-year-old male with COPD is experiencing difficulty in breathing. Which alteration in lung compliance is most likely contributing to his symptoms?

Accepted Answer

Increased lung compliance due to alveolar destruction

Answer

Increased airway resistance due to COPD

Answer

Normal lung compliance with isolated airway obstruction

Answer

Decreased lung compliance due to restrictive lung disease

Question 4

Which shift in the oxygen-hemoglobin dissociation curve facilitates oxygen unloading in the tissues?

Accepted Answer

Shift to the right

Answer

Shift to the left

Answer

No shift

Answer

Downward shift

Question 5

A patient with severe asthma is found to have a decreased FEV1/FVC ratio. Which of the following best describes the underlying physiological change?

Accepted Answer

Increased airway resistance

Answer

Decreased lung compliance

Answer

Increased diffusion capacity

Answer

Decreased pulmonary capillary pressure

Question 6

A patient with chronic obstructive pulmonary disease (COPD) exhibits signs of respiratory acidosis. What is the primary cause?

Accepted Answer

Increased carbon dioxide retention

Answer

Decreased carbon dioxide retention

Answer

Decreased bicarbonate reabsorption

Answer

Increased bicarbonate reabsorption

Question 7

A patient with diabetic ketoacidosis (DKA) presents with Kussmaul breathing. Which compensatory mechanism is he demonstrating?

Accepted Answer

Increased CO2 elimination

Answer

Increased CO2 retention

Answer

Decreased bicarbonate reabsorption

Answer

Increased bicarbonate excretion

Question 8

A 50-year-old male with COPD is experiencing increasing dyspnea, cyanosis, hypercapnia, and hypoxemia. What is the PRIMARY pathophysiological mechanism responsible for impaired gas exchange in this patient?

Accepted Answer

Ventilation-perfusion mismatch and reduced alveolar surface area impairing gas exchange

Answer

Airflow limitation due to chronic inflammation and structural changes leading to decreased alveolar ventilation

Answer

Increased airway resistance leading to reduced minute ventilation and alveolar hypoventilation

Answer

Decreased pulmonary capillary blood flow due to hypoxic vasoconstriction

Question 9

A 60-year-old man with chronic obstructive pulmonary disease (COPD) presents with hypercapnia. Which of the following physiological mechanisms is most likely contributing to his elevated CO2 levels?

Accepted Answer

Decreased alveolar ventilation

Answer

Decreased metabolic CO2 production

Answer

Increased gas diffusion capacity

Answer

Increased dead space ventilation

Question 10

Which process describes the transfer of oxygen from the lungs to the blood?

Accepted Answer

Diffusion

Answer

Filtration

Answer

Reabsorption

Answer

Active transport

Respiratory System — MCQs

Respiratory System — MCQs

On this page

Practice by Chapter

Want unlimited practice?