Respiratory System Histology — MCQs
Surfactant acts to maintain lung compliance by decreasing which factor?
A patient presents with hoarseness and laryngoscopy reveals a warty, cauliflower-like growth on the vocal cord. Identify the most likely lesion.
Which condition is characterized by a specific appearance on CT scans that resembles small centrilobular nodules with branching linear structures?
While performing drainage of fluid from the pleural cavity, the needle is introduced through all of the following structures except which one?
Mesothelioma is closely associated with which of the following?
The nasopharynx is primarily lined by which type of epithelium?
Reinke's layer is seen in:
Biopsy of the exposed surface of the palatine tonsil reveals which type of tissue?
Epithelial lining of the urinary bladder is?
The lower two thirds of the following hematoxylin and eosin stained specimen is similar in appearance to which of the following structures?
Respiratory System Histology Indian Medical PG Practice Questions and MCQs
Question 1: Surfactant acts to maintain lung compliance by decreasing which factor?
- A. Surface tension (Correct Answer)
- B. Pleural fluid secretion
- C. Intrathoracic pressure
- D. Pleural pressure
Explanation: ***Surface tension*** - **Surfactant** directly reduces the **surface tension** at the air-liquid interface within the alveoli. - By lowering surface tension, surfactant prevents alveolar collapse, particularly at low lung volumes, and increases **lung compliance**. *Intrathoracic pressure* - **Intrathoracic pressure** (also known as pleural pressure) is the pressure within the chest cavity, which fluctuates with breathing. - While surfactant affects lung mechanics, it doesn't directly influence the overall intrathoracic pressure. *Pleural fluid secretion* - **Pleural fluid** lubricates the pleural surfaces and is secreted by the pleural membranes. - Surfactant's primary role is in the alveoli to reduce surface tension, not to regulate **pleural fluid secretion**. *Pleural pressure* - **Pleural pressure** is the pressure in the space between the parietal and visceral pleura. - Surfactant improves lung compliance, which indirectly affects how pressure changes during breathing, but it doesn't directly control the **pleural pressure** itself.
Question 2: A patient presents with hoarseness and laryngoscopy reveals a warty, cauliflower-like growth on the vocal cord. Identify the most likely lesion.
- A. Laryngeal papilloma (Correct Answer)
- B. Laryngeal malignancy
- C. Tracheomalacia
- D. Reinke’s edema
Explanation: ***Laryngeal papilloma*** - **Hoarseness** and a **warty, cauliflower-like growth** on the vocal cord are classic descriptions of a laryngeal papilloma, often caused by **HPV infection**. - These lesions can be solitary or multiple, and while benign, they can recur and cause voice changes and respiratory obstruction. *Laryngeal malignancy* - While hoarseness is a common symptom of laryngeal malignancy, the description of a **"warty, cauliflower-like growth"** is more characteristic of a papilloma than most typical carcinomas, which might appear more ulcerative or infiltrative. - Malignancies are more commonly associated with risk factors like **smoking and alcohol use**, and often present with other symptoms like dysphagia or weight loss. *Tracheomalacia* - **Tracheomalacia** refers to softening of the tracheal cartilage, leading to airway collapse, typically causing stridor or respiratory distress. - It does not present as a **discrete growth** on the vocal cords but rather as a diffuse structural weakness of the trachea. *Reinke’s edema* - **Reinke's edema** (polypoid corditis) is characterized by a **gelatinous or fluid-filled swelling** of the vocal cords, usually associated with chronic irritation like smoking. - It presents as a swollen, boggy appearance of the vocal cords, not a warty or cauliflower-like growth.
Question 3: Which condition is characterized by a specific appearance on CT scans that resembles small centrilobular nodules with branching linear structures?
- A. Pulmonary tuberculosis (Correct Answer)
- B. Silicosis
- C. Pulmonary hydatid cyst
- D. Small cell carcinoma
Explanation: ***Pulmonary tuberculosis*** - This description ("small centrilobular nodules with **branching linear structures**") is characteristic of the **tree-in-bud pattern** seen on CT scans, which is a hallmark finding in active **endobronchial spread of tuberculosis**. - The tree-in-bud pattern results from the impaction of tuberculous **granulomas** and caseous material in the terminal and respiratory bronchioles. *Silicosis* - Characterized by multiple small, well-defined **nodules** (often in the upper lobes) that tend to calcify, but typically lacks the fine **branching linear structures**. - It’s associated with occupational exposure to **silica dust** and may progress to **massive progressive fibrosis**. *Pulmonary hydatid cyst* - Presents as a well-defined, usually **single, large cystic lesion** on CT, often with internal membranes if ruptured (water lily sign or crumpled membrane sign). - It does not typically manifest with small centrilobular nodules or branching linear structures. *Small cell carcinoma* - Usually appears as a **large central mass**, often with mediastinal lymphadenopathy, and sometimes associated with obstructive pneumonitis. - It does not typically present as diffuse small centrilobular nodules with branching patterns.
Question 4: While performing drainage of fluid from the pleural cavity, the needle is introduced through all of the following structures except which one?
- A. Thoracic fascia
- B. Skin
- C. Pulmonary pleura (Correct Answer)
- D. Intercostal muscles
Explanation: ***Pulmonary pleura*** - The needle for pleural fluid drainage, or thoracentesis, passes through the **parietal pleura** [1] but not the **pulmonary (visceral) pleura**. - Puncturing the pulmonary pleura would indicate the needle has entered the lung parenchyma, which is an avoidable complication. *Skin* - The **skin** is the outermost layer and the first structure the needle penetrates during a thoracentesis. - It must be sterilized prior to the procedure. *Thoracic fascia* - The needle passes through the **superficial fascia** and then the **deep fascia** covering the intercostal muscles. - These fascial layers provide structural support and enclose the musculature of the thoracic wall. *Intercostal muscles* - The needle traverses the **external**, **internal**, and **innermost intercostal muscles** as it moves deeper into the thoracic cavity. - The neurovascular bundle runs between the internal and innermost intercostals, hence the needle is typically inserted over the superior border of the rib to avoid it [1].
Question 5: Mesothelioma is closely associated with which of the following?
- A. Silicosis
- B. Anthracosis
- C. Byssinosis
- D. Asbestosis (Correct Answer)
Explanation: ***Asbestosis*** - Mesothelioma is a rare but aggressive cancer of the **pleura** or **peritoneum**, and its strongest known etiological link is with **asbestos exposure**. - Asbestos fibers can become lodged in the lungs and pleural lining, leading to chronic inflammation, DNA damage, and eventually oncogenic transformation. *Silicosis* - **Silicosis** is a lung disease caused by inhaling **crystalline silica dust**, primarily affecting miners, construction workers, and foundry workers. - While it can lead to pulmonary fibrosis and an increased risk of tuberculosis and lung cancer, it is not directly associated with mesothelioma. *Anthracosis* - **Anthracosis** is often seen in coal miners and urban dwellers due to the inhalation of **carbon dust**, leading to the accumulation of pigment in the lungs. - This condition is generally benign but can contribute to the development of **coal worker's pneumoconiosis**, which is distinct from mesothelioma. *Byssinosis* - **Byssinosis** is an occupational lung disease caused by the inhalation of **cotton dust** or other textile dusts, typically affecting textile workers. - Symptoms include chest tightness and shortness of breath, particularly after beginning work after a break, and it is unrelated to mesothelioma.
Question 6: The nasopharynx is primarily lined by which type of epithelium?
- A. Stratified squamous keratinized
- B. Ciliated columnar (Correct Answer)
- C. Cuboidal
- D. Stratified squamous nonkeratinized
Explanation: ***Ciliated columnar*** - The **nasopharynx** is lined by **pseudostratified ciliated columnar epithelium** with goblet cells, also known as respiratory epithelium [2]. - This specialized epithelium is crucial for **warming**, **humidifying**, and **filtering** inhaled air before it reaches the lungs [1]. *Stratified squamous nonkeratinized* - This type of epithelium is found in areas subject to **abrasion** and needing protection, such as the **oral cavity**, pharynx (oropharynx and laryngopharynx), and esophagus. - It is not primary in the nasopharynx, which requires ciliary action for particle removal. *Stratified squamous keratinized* - This robust epithelium is characteristic of areas that require significant **protection against friction** and **drying**, such as the **epidermis of the skin**. - It is not found in the nasopharynx due to its lack of flexibility and ciliary function. *Cuboidal* - **Cuboidal epithelium** is typically found in glands and kidney tubules, where its function includes **secretion** and **absorption**. - It lacks the specialized cilia and goblet cells necessary for the respiratory function of the nasopharynx [2].
Question 7: Reinke's layer is seen in:
- A. Vocal cord (Correct Answer)
- B. Tympanic membrane
- C. Cochlea
- D. Reissner's membrane
Explanation: ***Vocal cord*** - **Reinke's space**, also known as Reinke's layer, is the superficial layer of the **lamina propria** of the vocal cord. - This layer is crucial for the **vibration of the vocal folds**, which is essential for sound production. *Tympanic membrane* - The **tympanic membrane**, or eardrum, is a thin membrane that separates the external ear from the middle ear [1]. [2]. - It vibrates in response to **sound waves** and transmits these vibrations to the ossicles, playing a role in hearing, not vocalization [1], [2]. *Cochlea* - The **cochlea** is a spiral-shaped cavity in the inner ear involved in the sense of hearing [2]. - It contains the **organ of Corti**, which converts sound vibrations into nerve impulses but has no connection to vocal cord anatomy [2]. *Reissner's membrane* - **Reissner's membrane** (vestibular membrane) is a thin membrane that separates the scala vestibuli from the scala media within the cochlea. - Its primary function is to maintain the **composition of the endolymph** in the scala media, and it is part of the auditory system, not the larynx.
Question 8: Biopsy of the exposed surface of the palatine tonsil reveals which type of tissue?
- A. Stratified squamous epithelium (Correct Answer)
- B. Simple squamous epithelium
- C. Simple columnar epithelium
- D. Pseudostratified columnar ciliated epithelium
Explanation: The palatine tonsils are part of the **oropharynx**, which is subjected to mechanical abrasion from food and drink. **Stratified squamous epithelium** provides robust protection against such friction and is characteristic of surfaces needing high wear resistance. *Simple squamous epithelium* - This type of epithelium is found in areas where **diffusion** or **filtration** is important, such as the lining of blood vessels (endothelium) and alveoli of the lungs. - It would not provide adequate protection for the exposed surface of the tonsil that is subject to frequent mechanical stress. *Simple columnar epithelium* - Characterized by cells taller than they are wide, often found in the **gastrointestinal tract** for absorption and secretion. - It lacks the multi-layered structure needed for protection against the abrasive forces typical in the oropharynx. *Pseudostratified columnar ciliated epithelium* - This epithelium is primarily found in the **respiratory tract**, where its cilia help move mucus and trapped particles. - While it offers some protection, its primary function is not mechanical resistance, and it is not found on the exposed surfaces of the palatine tonsils.
Question 9: Epithelial lining of the urinary bladder is?
- A. Squamous epithelium
- B. Transitional epithelium (Correct Answer)
- C. Cuboidal epithelium
- D. Columnar epithelium
Explanation: ***Transitional epithelium*** - The urinary bladder is lined by **transitional epithelium**, also known as **urothelium** [1]. - This specialized epithelium can stretch and flatten when the bladder fills with urine, and then contract when it empties, a crucial adaptation for its function. *Squamous epithelium* - **Stratified squamous epithelium** is typically found in areas subject to abrasion, such as the skin, esophagus, and vagina. - It does not possess the unique distensibility required for the urinary bladder's function. *Cuboidal epithelium* - **Cuboidal epithelium** is commonly found in glands and kidney tubules, where it is involved in secretion and absorption. - It is not specialized for the significant stretching and recoiling seen in the urinary bladder. *Columnar epithelium* - **Columnar epithelium** is primarily involved in secretion and absorption and is found in regions like the gastrointestinal tract and some glandular ducts. - It lacks the necessary structural characteristics to accommodate the large volume changes of the urinary bladder.
Question 10: The lower two thirds of the following hematoxylin and eosin stained specimen is similar in appearance to which of the following structures?
- A. Articular disk
- B. Pinna
- C. Epiphyseal growth plate
- D. Intervertebral disk (Correct Answer)
Explanation: ***Intervertebral disk*** - The lower two-thirds of the specimen shows **hyaline-like cartilage** that histologically resembles the **transition zone** of the intervertebral disk, where the inner annulus fibrosus transitions from the nucleus pulposus. - While the nucleus pulposus itself is gelatinous and notochordal in origin, the **inner annulus fibrosus** contains fibrocartilage with regions that can appear similar to hyaline cartilage, particularly in the transitional zones. - The specimen's appearance, with **chondrocytes in lacunae** within a relatively homogeneous matrix, matches the cartilaginous components found in intervertebral disk structure. *Articular disk* - Articular disks are composed predominantly of **fibrocartilage**, characterized by **dense parallel collagen fiber bundles** clearly visible in the matrix and chondrocytes arranged in linear rows between collagen bundles. - The homogeneous matrix appearance in the specimen lacks the prominent fibrous architecture typical of articular disks. *Pinna* - The pinna (external ear) is supported by **elastic cartilage**, which contains abundant **elastic fibers** in its extracellular matrix providing flexibility and resilience. - With H&E staining, elastic cartilage would show a more textured matrix, and special stains would demonstrate extensive elastic fiber networks not present in this specimen. *Epiphyseal growth plate* - While the epiphyseal growth plate consists of **hyaline cartilage**, it exhibits highly characteristic **zonal organization**: resting zone, proliferative zone (with columnar arrangement), hypertrophic zone, and zone of calcification. - The specimen lacks the distinct columnar arrangement and zonal stratification that defines an active epiphyseal growth plate.
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