Functional Anatomy of Respiratory System — MCQs
In a preterm baby with respiratory distress syndrome, which of the following lipids would be deficient?
What is the uppermost structure in left lung hilum?
Damage to pneumotaxic center along with vagus nerve causes which type of respiration?
The incidence of a foreign body being aspirated into the right lung is higher than into the left lung. All of the following statements support this, EXCEPT?
Which of the following is related to the mediastinal part of the right lung?
Investigation of choice in bronchiectasis?
Arrange lung hilar structure from anterior to posterior:- 1. Primary bronchus 2. Bronchial artery 3. Pulmonary vein 4. Pulmonary artery
Name the muscles being used in climbing a tree as shown in the figure.
Most common cause of death in burns patients is
Which of the following is not included in the Child-Turcotte-Pugh scoring system?
Functional Anatomy of Respiratory System Indian Medical PG Practice Questions and MCQs
Question 1: In a preterm baby with respiratory distress syndrome, which of the following lipids would be deficient?
- A. Cardiolipin
- B. Sphingomyelin
- C. Phosphatidylinositol
- D. Lecithin (Correct Answer)
Explanation: ***Lecithin*** - **Lecithin** (also known as **phosphatidylcholine**) is the primary component of **surfactant** in the lungs, which reduces surface tension and prevents alveolar collapse. - In **preterm babies**, insufficient production of lecithin due to immature lung development leads to **respiratory distress syndrome (RDS)**. *Cardiolipin* - **Cardiolipin** is a major phospholipid found in the **inner mitochondrial membrane**, crucial for oxidative phosphorylation. - Deficiency is associated with mitochondrial disorders like **Barth syndrome**, not primary respiratory distress. *Sphingomyelin* - **Sphingomyelin** is a significant component of **cell membranes** and **myelin sheaths**, important for nerve insulation. - While present in the lungs, its primary role is not in surface tension reduction, and its deficiency is not directly linked to RDS. *Phosphatidylinositol* - **Phosphatidylinositol** is a precursor for various **signaling molecules** and plays a role in cell membrane structure. - While involved in cellular processes, it is not the critical surfactant component whose deficiency causes RDS.
Question 2: What is the uppermost structure in left lung hilum?
- A. Pulmonary artery (Correct Answer)
- B. Pulmonary vein
- C. Bronchial artery
- D. Left mainstem bronchus
Explanation: ***Pulmonary artery*** - In the **left lung hilum**, the **pulmonary artery** typically lies superior to the bronchus. - This anatomical position helps differentiate it from the relations in the right lung hilum, where the pulmonary artery is anterior to the bronchus. *Pulmonary vein* - The **pulmonary veins** are usually located anterior and inferior to the bronchus in both lung hila. - They tend to be the most anterior and inferior structures carrying oxygenated blood from the lungs. *Bronchial artery* - **Bronchial arteries** are smaller vessels that typically run on the posterior surface of the bronchi. - They are not considered the uppermost main structure in the hilum. *Left mainstem bronchus* - The **left mainstem bronchus** is usually found inferior to the pulmonary artery and posterior to the pulmonary veins in the left hilum. - It is a prominent structure but not the most superior.
Question 3: Damage to pneumotaxic center along with vagus nerve causes which type of respiration?
- A. Cheyne-Stokes breathing
- B. Deep and slow breathing
- C. Shallow and rapid breathing
- D. Apneustic breathing (Correct Answer)
Explanation: ***Apneustic breathing*** - Damage to the **pneumotaxic center** prevents the normal inhibition of inspiration, leading to **prolonged inspiratory gasps**. - **Vagal nerve damage** further removes the inhibitory feedback from the lungs, exacerbating the inspiratory "holds" characteristic of apneustic breathing. *Cheyne-Stokes breathing* - This pattern is characterized by a **crescendo-decrescendo pattern** of breathing, interspersed with periods of **apnea**. - It is often associated with conditions like **heart failure**, stroke, or severe neurological damage, not specifically the pneumotaxic center and vagus nerve. *Deep and slow breathing* - This pattern can be seen in conditions like **Kussmaul breathing** (due to metabolic acidosis) or as a compensatory mechanism. - It does not directly result from the combined damage of the **pneumotaxic center** and the **vagus nerve**. *Shallow and rapid breathing* - This pattern is commonly seen in restrictive lung diseases, anxiety, or pain, where tidal volume is decreased and respiratory rate increased. - It does not reflect the **prolonged inspiration** that would result from a compromised pneumotaxic center and vagal input.
Question 4: The incidence of a foreign body being aspirated into the right lung is higher than into the left lung. All of the following statements support this, EXCEPT?
- A. Tracheal bifurcation directs the foreign body to the right lung
- B. Right lung is shorter and wider than left lung (Correct Answer)
- C. Right inferior lobar bronchus is in continuation with the right principal bronchus
- D. Right principal bronchus is more vertical than the left bronchus
Explanation: ***Right lung is shorter and wider than left lung*** - This statement, while anatomically true, does **NOT directly explain** why foreign bodies preferentially enter the right lung - The dimensions of the **lung parenchyma itself** (shorter due to the diaphragm being pushed up by the liver, and wider) are unrelated to aspiration patterns - What determines aspiration is the **bronchial tree geometry** (angle, diameter, verticality), not the overall lung size - This is the EXCEPTION - it's a true anatomical fact but doesn't support the aspiration phenomenon *Incorrect - Tracheal bifurcation directs the foreign body to the right lung* - This statement DOES support higher right aspiration, so it cannot be the answer - The **carina angle** and bifurcation geometry favor the right side, directing foreign bodies preferentially to the right main bronchus - This is a key anatomical reason for the higher incidence *Incorrect - Right inferior lobar bronchus is in continuation with the right principal bronchus* - This statement DOES support higher right aspiration - After the right superior lobar bronchus branches off, the **intermediate bronchus** continues more directly toward the inferior lobe - This creates a straighter pathway from trachea → right main bronchus → intermediate bronchus → inferior lobar bronchus - Foreign bodies follow this direct path, often lodging in the right inferior lobe *Incorrect - Right principal bronchus is more vertical than the left bronchus* - This statement DOES support higher right aspiration - The right main bronchus diverges at approximately **25 degrees** from vertical, while the left diverges at **45 degrees** - This more vertical orientation makes the right bronchus a more direct continuation of the trachea - Gravity and airflow naturally direct aspirated material down this straighter path
Question 5: Which of the following is related to the mediastinal part of the right lung?
- A. Arch of aorta
- B. SVC (Correct Answer)
- C. Pulmonary trunk
- D. Left atrium
Explanation: ***SVC*** - The **superior vena cava (SVC)** lies to the right side of the mediastinum and is intimately related to the mediastinal surface of the **right lung** [1]. - The SVC drains into the **right atrium** and forms an important landmark in the superior mediastinum, immediately adjacent to the right lung hilum [1]. - Creates a prominent **vertical groove** on the mediastinal surface of the right lung [1]. *Arch of aorta* - The **arch of aorta** is located in the superior mediastinum but lies to the **left** of the trachea and mediastinal structures, thus relating more to the **left lung**. - It arches over the root of the left lung and creates an impression on the **left mediastinal surface**, not the right. *Pulmonary trunk* - The **pulmonary trunk** arises from the right ventricle and ascends in the mediastinum, but it is primarily situated **anterior and to the left** of the ascending aorta. - It bifurcates into the right and left pulmonary arteries **anterior to the left main bronchus**, creating impressions mainly on the **left lung's mediastinal surface**. *Left atrium* - The **left atrium** forms the base of the heart and is located on the **left and posterior** aspect of the mediastinum. - It creates an impression on the **left lung's mediastinal surface**, particularly the lower part, but has no direct relation to the right lung.
Question 6: Investigation of choice in bronchiectasis?
- A. Bronchoscopy
- B. Chest X-ray
- C. MRI
- D. HRCT (Correct Answer)
Explanation: ***HRCT*** - **High-resolution computed tomography (HRCT)** is the gold standard for diagnosing bronchiectasis, as it provides detailed images of the bronchial tree. - It effectively visualizes the characteristic **bronchial dilation**, **lack of bronchial tapering**, and **"signet-ring" appearance** of the airways. *MRI* - **Magnetic resonance imaging (MRI)** is generally not the primary imaging modality for bronchiectasis due to its lower spatial resolution compared to CT for lung parenchyma. - While it can provide functional information, it is not as effective in visualizing the characteristic anatomical changes of bronchiectasis. *Bronchoscopy* - **Bronchoscopy** is an invasive procedure primarily used to identify the cause of bronchiectasis (e.g., foreign body, infection, endobronchial obstruction) or for therapeutic lavage. - It is not the initial diagnostic investigation of choice for confirming the presence and extent of bronchiectasis itself. *Chest X-ray* - A **chest X-ray** may show non-specific findings such as increased bronchial wall opacity or tram-track lucencies, which are suggestive of bronchiectasis but not definitive. - It lacks the sensitivity and specificity of HRCT to confirm the diagnosis and delineate the extent of the disease.
Question 7: Arrange lung hilar structure from anterior to posterior:- 1. Primary bronchus 2. Bronchial artery 3. Pulmonary vein 4. Pulmonary artery
- A. 4,3,2,1
- B. 3,4,1,2 (Correct Answer)
- C. 1,2,3,4
- D. 2,3,4,1
Explanation: ***3,4,1,2*** - This order represents the typical arrangement of major structures in the **lung hilum** from anterior to posterior: **pulmonary vein (most anterior)**, **pulmonary artery**, **primary bronchus**, and finally the **bronchial artery (most posterior)**. - The **pulmonary vein** is usually the most anterior structure, while the **bronchial artery** often runs along the posterior aspect of the bronchus [1]. *4,3,2,1* - This order incorrectly places the **pulmonary artery** as the most anterior structure, which is generally not the case in the hilum. - The **primary bronchus** is usually more posterior than the main pulmonary artery. *1,2,3,4* - This order is incorrect as it places the **primary bronchus** as the most anterior structure, which is anatomically inaccurate for the lung hilum. - The **pulmonary veins** are typically the most anterior hilar structures. *2,3,4,1* - This order incorrectly positions the **bronchial artery** as the most anterior component, while it is usually the most posterior or associated closely with the posterior aspect of the bronchus. - The **pulmonary vein** should be anterior to the pulmonary artery and bronchus.
Question 8: Name the muscles being used in climbing a tree as shown in the figure.
- A. Latissimus dorsi and pectoralis major (Correct Answer)
- B. Teres major and pectoralis major
- C. Teres minor and pectoralis minor
- D. External oblique and pectoralis major
Explanation: ***Latissimus dorsi and pectoralis major*** - The **latissimus dorsi** is a large, powerful muscle responsible for adduction, extension, and internal rotation of the arm, all crucial for pulling the body upward during climbing. - The **pectoralis major** is a large, fan-shaped muscle that helps with adduction, flexion, and internal rotation of the humerus, also vital for pulling oneself up against gravity. *Teres major and pectoralis major* - While the **pectoralis major** is involved, the **teres major** is a smaller muscle that primarily assists the latissimus dorsi in extension, adduction, and internal rotation of the humerus, but is not as dominant in the main pulling action as the latissimus dorsi. - The primary pulling force comes from larger muscles, making the teres major a less significant contributor to the overall climbing action. *Teres minor and pectoralis minor* - The **teres minor** is part of the rotator cuff and primarily functions in external rotation of the humerus, which is not a primary movement for pulling oneself up. - The **pectoralis minor** is a small, thin muscle that stabilizes the scapula and depresses the shoulder; it does not directly contribute to the powerful pulling action needed for climbing. *External oblique and pectoralis major* - The **external oblique** is an abdominal muscle involved in trunk rotation and flexion, providing core stability but not directly contributing to the primary upper body pulling motion for climbing. - While the **pectoralis major** is correctly identified, the external oblique is not a primary muscle used for the upward pulling motion in climbing.
Question 9: Most common cause of death in burns patients is
- A. Asphyxia
- B. Cardiac arrest
- C. Hypovolemic shock
- D. Septic shock (Correct Answer)
Explanation: ***Septic shock*** - **Septic shock** is the leading cause of death in burn patients, particularly in cases involving **large surface area burns**, due to compromised skin barrier allowing bacterial entry and systemic inflammatory response. - The extensive tissue damage, altered immune response, and requirement for invasive procedures (e.g., catheters, ventilator support) significantly increase the risk of developing **severe infections** leading to sepsis. *Asphyxia* - While **asphyxia** can be an immediate cause of death in fire-related incidents due to smoke inhalation and airway obstruction, it is less common as the primary cause of death overall in burn patients who survive the initial injury. - Patients who develop asphyxia often die at the **scene of the fire** or shortly after arrival, not during later stages of burn care. *Cardiac arrest* - **Cardiac arrest** can occur as a complication of severe burns due to **hypovolemia**, electrolyte imbalances, or direct cardiac injury, but it is often a *consequence* of other primary issues like sepsis or severe hypovolemic shock. - It is not typically cited as the most common *initial* or *primary* cause of death across the entire course of burn injury management. *Hypovolemic shock* - **Hypovolemic shock** is a major concern in the **initial phase** of burn injury due to massive fluid loss through the damaged skin. - While critical and a significant contributor to early mortality, effective **fluid resuscitation** protocols usually manage and prevent death from hypovolemic shock in patients who receive timely medical care.
Question 10: Which of the following is not included in the Child-Turcotte-Pugh scoring system?
- A. Encephalopathy
- B. ALT (Correct Answer)
- C. Albumin
- D. Ascites
Explanation: ***ALT*** - The **Child-Turcotte-Pugh (CTP) score** assesses the severity of **liver cirrhosis** and its prognosis, using parameters like bilirubin, albumin, INR, ascites, and encephalopathy. [1] - **Alanine aminotransferase (ALT)** levels are indicators of hepatocellular injury or inflammation but are not used in the CTP scoring system for chronic liver disease severity. [1] *Encephalopathy* - **Hepatic encephalopathy** is a crucial component of the CTP score, reflecting the liver's inability to detoxify harmful substances. [1] - Its presence and severity (graded 1-4) strongly correlate with a worse prognosis in **cirrhotic patients**. *Albumin* - **Albumin** levels are inversely correlated with the severity of liver dysfunction, as synthetic function of the liver declines. [1] - Low albumin (hypoalbuminemia) indicates poor **synthetic capacity** of the liver and is a prognostic marker in the CTP score. [1] *Ascites* - **Ascites**, the accumulation of fluid in the abdominal cavity, is a common complication of **portal hypertension** in advanced liver disease. [1] - Its presence and refractoriness are critical components of the CTP score, indicating significant fluid imbalance and circulatory dysfunction. [1]
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