Respiratory System — MCQs
What is the uppermost structure in left lung hilum?
Damage to pneumotaxic center along with vagus nerve causes which type of respiration?
Inlet of larynx is formed by:
All of the following are features of Lymph node histology except:
Angle of tracheal bifurcation is increased in which chamber of heart enlargement.
Bifurcation of the trachea is at which level?
Which structure is most likely injured in a 25-year-old man with a bullet wound in the neck, resulting in a tension pneumothorax and collapse of the right lung?
During thyroidectomy, damage to which nerve leads to loss of high-pitched voice?
Cobra poison is:
Which is associated with vasculitis of medium sized vessels
Respiratory System Indian Medical PG Practice Questions and MCQs
Question 1: 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 2: 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 3: Inlet of larynx is formed by:
- A. Aryepiglottic fold (Correct Answer)
- B. Vocal cord
- C. False vocal cord
- D. Folds from the base of the tongue to the epiglottis
Explanation: ***Aryepiglottic fold*** - The **inlet of the larynx** is the opening into the laryngeal cavity from the pharynx. - It is bordered anteriorly by the **epiglottis**, laterally by the **aryepiglottic folds**, and posteriorly by the **arytenoid cartilages** and **interarytenoid notch**. *False vocal cord* - The **false vocal cords** (ventricular folds) are located within the laryngeal cavity, inferior to the inlet. - They play a protective role but do not form the boundaries of the laryngeal inlet itself. *Folds from the base of the tongue to the epiglottis* - These folds, including the **glossoepiglottic folds**, connect the tongue to the epiglottis. - They are superior to the laryngeal inlet and are part of the oropharynx, not direct borders of the inlet. *Vocal cord* - The **true vocal cords** are responsible for voice production and are located deeper within the larynx, inferior to the false vocal cords. - They do not form any part of the laryngeal inlet.
Question 4: All of the following are features of Lymph node histology except:
- A. Both Efferent and Afferent are present
- B. Subcapsular sinus present
- C. Cortex and Medulla are present
- D. Red pulp and White pulp are present (Correct Answer)
Explanation: ***Red pulp and White pulp are present*** - **Red pulp** and **white pulp** are characteristic histological features of the **spleen**, not lymph nodes [1]. - The white pulp contains lymphoid follicles (PALS - periarteriolar lymphoid sheaths), while the red pulp is involved in filtering blood and destroying old red blood cells [1]. - This is the feature that does NOT belong to lymph node histology. *Both Efferent and Afferent are present* - Lymph nodes have multiple **afferent lymphatic vessels** that bring lymph into the node and usually one or two **efferent lymphatic vessels** that carry lymph away [2]. - This arrangement allows for efficient filtering of lymph and immune surveillance [2]. - This IS a feature of lymph nodes. *Subcapsular sinus present* - The **subcapsular sinus** is a space located directly beneath the capsule of the lymph node, which receives lymph from the afferent lymphatic vessels. - It contains a network of reticular fibers and macrophages, acting as the initial filtering area. - This IS a feature of lymph nodes. *Cortex and Medulla are present* - Lymph nodes are histologically divided into an outer **cortex** and an inner **medulla**. - The cortex contains lymphoid follicles (B-cell areas) and paracortical areas (T-cell areas), while the medulla consists of medullary cords and sinuses. - This IS a feature of lymph nodes.
Question 5: Angle of tracheal bifurcation is increased in which chamber of heart enlargement.
- A. Left ventricle
- B. Right atrium
- C. Right ventricle
- D. Left atrium (Correct Answer)
Explanation: ***Left atrium*** - An enlarged **left atrium** can lift the **left main bronchus**, increasing the angle between the two main bronchi, known as the **carinal angle** (or angle of tracheal bifurcation), visible on a chest X-ray. - This is a common radiological sign seen in conditions causing left atrial enlargement, such as **mitral stenosis** [2]. *Left ventricle* - **Left ventricular enlargement** primarily causes the cardiac apex to shift downward and laterally, but it typically does not directly impinge on the main bronchi to increase the carinal angle [1]. - While it can indirectly affect lung fields due to **pulmonary congestion**, it doesn't cause this specific sign [1]. *Right atrium* - **Right atrial enlargement** causes a bulging of the right border of the heart on a chest X-ray [1]. - It does not directly interact with or displace the main bronchi in a way that would alter the **tracheal bifurcation angle**. *Right ventricle* - **Right ventricular enlargement** can cause the heart to push into the retrosternal space and elevate the apex, but it generally does not impinge upon the main bronchi to change the **carinal angle** [1]. - Its effects are more focused on the anterior and rightward aspects of the heart.
Question 6: Bifurcation of the trachea is at which level?
- A. Opposite the disc between the T3-T4 vertebrae
- B. Opposite the disc between the T5-T6 vertebrae
- C. Opposite the disc between the T4-T5 vertebrae (Correct Answer)
- D. Opposite the disc between the T7-T8 vertebrae
Explanation: ***Opposite the disc between the T4-T5 vertebrae*** - The **trachea** bifurcates into the right and left main bronchi at the level of the **carina**. - In adults, this anatomical landmark consistently corresponds to the intervertebral disc between the **fourth and fifth thoracic vertebrae (T4-T5)**. *Opposite the disc between the T3-T4 vertebrae* - This level is generally **above the tracheal bifurcation** in most individuals. - The superior margin of the **manubrium sterni** is typically at the level of the T3 vertebral body, which is too high for the tracheal carina. *Opposite the disc between the T5-T6 vertebrae* - This level is generally **below the tracheal bifurcation**. - The **inferior mediastinum** begins roughly at the T5 level, which is after the carina. *Opposite the disc between the T7-T8 vertebrae* - This level is significantly **below the carina** and corresponds to the approximate level of the inferior aspect of the **heart** or the **diaphragmatic domes**. - No major tracheal branching occurs at this lower thoracic vertebral level.
Question 7: Which structure is most likely injured in a 25-year-old man with a bullet wound in the neck, resulting in a tension pneumothorax and collapse of the right lung?
- A. Costal pleura
- B. Cupula (Correct Answer)
- C. Right mainstem bronchus
- D. Right upper lobe bronchus
Explanation: ***Cupula*** - The **cupula** (or cervical pleura) extends into the root of the neck, superior to the first rib, making it vulnerable to neck injuries [1]. - A penetrating injury to this region can directly damage the pleura, leading to **pneumothorax** and subsequent lung collapse [1]. *Costal pleura* - The **costal pleura** lines the inner surface of the thoracic wall and would primarily be affected by injuries directly to the chest wall, not the neck [1]. - Injury to this part of the pleura is less likely to result from a **neck wound** causing a pneumothorax unless the wound extended significantly downwards. *Right mainstem bronchus* - The **right mainstem bronchus** is located deep within the mediastinum and would typically require a much deeper and more centrally located injury to be affected. - While mainstem bronchial injuries can cause **pneumothorax**, a bullet wound in the neck is less likely to reach this structure without causing more extensive mediastinal damage. *Right upper lobe bronchus* - The **right upper lobe bronchus** is also situated within the mediastinum, deep to the pleura and lung parenchyma. - An isolated injury to this bronchus from a neck wound is unlikely; simpler, more superficial structures like the **cupula** are more probable targets.
Question 8: During thyroidectomy, damage to which nerve leads to loss of high-pitched voice?
- A. External branch of the superior laryngeal nerve (Correct Answer)
- B. Hypoglossal nerve
- C. Vagus nerve
- D. Recurrent laryngeal nerve
Explanation: ***External branch of the superior laryngeal nerve*** - The **external branch of the superior laryngeal nerve** innervates the **cricothyroid muscle**, which is responsible for tensing the vocal cords. - Damage to this nerve paralyzes the cricothyroid muscle, leading to an inability to tense the vocal cords, resulting in a **monotonous voice** and **loss of high-pitched tones**. *Hypoglossal nerve* - The **hypoglossal nerve (CN XII)** controls the muscles of the **tongue**, affecting articulation and swallowing, but not vocal pitch directly. - Damage primarily causes **tongue deviation** and **difficulty with speech (dysarthria)** and swallowing. *Vagus nerve* - The **vagus nerve (CN X)** gives rise to both the **superior laryngeal nerve** and the **recurrent laryngeal nerve**. - While damage to the vagus nerve trunk would affect vocalization, the question specifically asks about loss of high-pitched voice, which points to a more localized injury to one of its branches. *Recurrent laryngeal nerve* - The **recurrent laryngeal nerve** innervates most of the intrinsic laryngeal muscles, including the **thyroarytenoid** and **posterior cricoarytenoid muscles**, primarily affecting vocal cord adduction and abduction. - Damage typically causes **hoarseness** due to vocal cord paralysis, and in severe cases, difficulty breathing, but it does not specifically lead to the *loss of high-pitched voice* as directly as superior laryngeal nerve damage.
Question 9: Cobra poison is:
- A. Vasculotoxic
- B. Myotoxic
- C. Neurotoxic (Correct Answer)
- D. Cardiotoxic
Explanation: ***Neurotoxic*** - Cobra venom contains **alpha-neurotoxins** that block **nicotinic acetylcholine receptors** at neuromuscular junctions, causing flaccid paralysis. - The primary cause of death is **respiratory failure** due to paralysis of respiratory muscles, making neurotoxicity the dominant mechanism. *Vasculotoxic* - Vasculotoxic effects are characteristic of **viper venoms**, causing bleeding, swelling, and tissue necrosis. - Cobra venom's primary action targets the **nervous system**, not blood vessels. *Myotoxic* - Myotoxic venoms directly damage **muscle tissue**, leading to rhabdomyolysis and muscle pain. - While minor muscle effects may occur, **neurotoxicity** remains the predominant and life-threatening mechanism in cobra envenomation. *Cardiotoxic* - Some cobra venoms contain **cardiotoxins**, but these are secondary to the primary neurotoxic effects. - The main cause of cardiovascular collapse is **respiratory paralysis**, not direct cardiac toxicity.
Question 10: Which is associated with vasculitis of medium sized vessels
- A. Wegener's granulomatosis
- B. Temporal arteritis
- C. Polyarteritis nodosa (Correct Answer)
- D. Henoch-Schönlein purpura
Explanation: ***Polyarteritis nodosa*** - **Polyarteritis nodosa (PAN)** is a **necrotizing vasculitis** of **medium-sized or small arteries**, but not arterioles, capillaries, or venules [1]. - It classically affects the **renal and visceral arteries**, sparing the pulmonary circulation, and is associated with **aneurysms** and stenoses. *Temporal arteritis* - This is a form of **large-vessel vasculitis** primarily affecting the **temporal and other cranial arteries** [1]. - It is typically seen in older adults and can cause **headache**, **jaw claudication**, and **blindness**. *Wegener's granulomatosis* - Now known as **Granulomatosis with Polyangiitis (GPA)**, this vasculitis affects **small vessels** and is characterized by a **granulomatous inflammation** of the upper and lower respiratory tracts and kidneys [1]. - It is associated with **PR3-ANCA (c-ANCA)** positivity. *Henoch-Schönlein purpura* - This is an **IgA vasculitis** affecting **small vessels**, typically presenting with **palpable purpura**, arthritis, abdominal pain, and renal involvement (nephritis) [1]. - It is the most common form of vasculitis in children.
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