Question 1: What is the narrowest part of the airway in an adult?
A) Trachea
B) Glottis
C) Cricoid cartilage
D) Bronchioles
Explanation: The glottis is formed by the vocal cords and the space between them. In adults, it is the narrowest part of the upper airway due to its variable size, depending on the position and tension of the vocal cords. In contrast, the cricoid cartilage (answer c), although the narrowest part of the airway in children, is relatively wider in adults and no longer the anatomical bottleneck. Conditions such as vocal cord paralysis, laryngeal edema (e.g., due to anaphylaxis), or foreign body aspiration can severely restrict airflow at the glottis. This leads to symptoms like stridor or respiratory distress. When inserting an endotracheal tube during anesthesia or critical care, passing the tube through the glottis can be challenging because of its narrow size. Proper visualization (using a laryngoscope) is critical to avoid trauma.
Question 2: Which cartilage is shaped like a signet ring and forms a complete ring around the airway?
A) Thyroid cartilage
B) Cricoid cartilage
C) Arytenoid cartilage
D) Epiglottis
Explanation:The cricoid cartilage is the only complete circular cartilage in the airway, distinguishing it from other cartilages like the thyroid and arytenoid cartilages, which are not complete rings. The posterior portion of the cricoid cartilage is broader and taller (resembling the signet part of the ring), while the anterior portion, known as the arch, is narrower and lower. The cricoid cartilage is a critical landmark for performing an emergency cricothyrotomy. The cricothyroid membrane, located between the cricoid and thyroid cartilages, is punctured to establish a temporary airway when intubation is not possible. During intubation, pressure is sometimes applied to the cricoid cartilage (Sellick’s maneuver) to compress the esophagus and prevent regurgitation of stomach contents into the airway. This technique helps reduce the risk of aspiration, although its routine use is debated.
Question 3: Which structure prevents food from entering the trachea during swallowing?
A) Arytenoid cartilage
B) Epiglottis
C) Glottis
D) Cricoid cartilage
Explanation: The epiglottis is a leaf-shaped cartilage located at the root of the tongue, above the laryngeal inlet. During swallowing, the larynx elevates, and the epiglottis tilts downward to cover the glottis (the opening of the larynx). This action ensures that ingested material is diverted away from the airway and into the esophagus. Dysfunction of the epiglottis, such as in neurological disorders (e.g., stroke or Parkinson’s disease), can lead to aspiration, where food or liquids enter the airway. This can result in aspiration pneumonia, a serious complication. An inflammation of the epiglottis, commonly caused by bacterial infection (e.g., Haemophilus influenzae type b in unvaccinated individuals), can lead to swelling and airway obstruction. Symptoms include stridor, drooling, and respiratory distress. Prompt airway management is crucial to prevent fatal outcomes.
Question 4: What is the primary epithelial lining of the trachea?
A) Stratified squamous epithelium
B) Simple columnar epithelium
C) Pseudostratified ciliated columnar epithelium
D) Simple squamous epithelium
Explanation: The primary epithelial lining of the trachea is pseudostratified ciliated columnar epithelium (answer c). The cells appear to be layered (hence "pseudostratified") because their nuclei are at different levels, but all cells are attached to the basement membrane, making it a single layer. This epithelium is ciliated, meaning it has hair-like projections (cilia) on its surface that help in the coordinated movement of mucus and trapped particles out of the respiratory tract, a process known as the mucociliary escalator. Goblet cells interspersed within this epithelium produce mucus, which traps dust, bacteria, and other inhaled debris. Chronic exposure to irritants like cigarette smoke can cause metaplasia, where the pseudostratified ciliated columnar epithelium is replaced by stratified squamous epithelium. While squamous epithelium offers better mechanical protection, it lacks cilia and goblet cells, impairing mucociliary clearance and predisposing to respiratory infections.
Question 5: Which of the following is NOT a part of the conducting zone?
A) Trachea
B) Bronchioles
C) Alveolar ducts
D) Main bronchi
Explanation: The alveolar ducts (answer c) belong to the respiratory zone, which is responsible for gas exchange. In contrast, the conducting zone consists of structures that provide a passage for air to move into and out of the lungs but do not directly participate in gas exchange. The walls of the conducting zone structures are too thick for gas exchange to occur. The Respiratory Zone begins at the respiratory bronchioles and includes alveolar ducts and alveoli. These structures have thin walls and are richly supplied with capillaries, allowing for the diffusion of oxygen and carbon dioxide. The alveolar ducts specifically lead to clusters of alveoli where gas exchange primarily occurs.
Question 6: How many lobar bronchi are present in the human body?
A) 2
B) 3
C) 5
D) 6
Explanation: The lungs are divided into lobes, and each lobe is supplied by a corresponding lobar (secondary) bronchus. The Right lung has three lobes (upper, middle, and lower). Therefore, it has three lobar bronchi. The Left lung has two lobes (upper and lower). Consequently, it has two lobar bronchi.
Question 7: Which structure divides the trachea into the left and right main bronchi?
A) Carina
B) Cricoid cartilage
C) Thyroid cartilage
D) Trachealis muscle
Explanation: The carina is situated at the level of the T4-T5 vertebrae and marks the bifurcation of the trachea into the right main bronchus and the left main bronchus. It is shaped like a keel (ridge) and has sensitive mucosa, making it highly responsive to mechanical stimulation, which can trigger the cough reflex.
Question 8: What is the function of the trachealis muscle?
A) Open the trachea during swallowing
B) Opens the trachea during breathing
C) Adjust the diameter of the trachea
D) Anchors the trachea to the esophagus
Explanation: The trachealis muscle spans the gap between the free ends of the C-shaped tracheal cartilage rings.It lies adjacent to the esophagus, forming the posterior boundary of the trachea. Contraction of the muscle narrows the tracheal diameter, which increases the velocity of airflow. This is particularly useful during actions like coughing, helping to expel mucus or foreign particles. Relaxation of the muscle expands the tracheal diameter, allowing for greater airflow during heavy breathing or increased oxygen demand, such as during exercise.
Question 9: Which bronchi is more vertical and wider, making it a common site for aspiration?
A) Right main bronchus
B) Left main bronchus
C) Lobar bronchi
D) Segmental bronchi
Explanation: The right main bronchus is wider, shorter, and more vertically aligned with the trachea, forming an angle of approximately 20–25 degrees, while the left main bronchus deviates more sharply at an angle of 45–55 degrees. The right lower lobe is the most common site for aspiration of foreign bodies and aspiration pneumonia because of the anatomy of the right main bronchus. During intubation, an endotracheal tube can accidentally enter the right main bronchus due to its orientation, leading to inadequate ventilation of the left lung and resultant hypoxemia. Proper positioning of the tube is confirmed using chest X-ray or auscultation.
Question 10: What is the innervation of the larynx below the vocal cords?
A) Superior laryngeal nerve
B) Recurrent laryngeal nerve
C) Glossopharyngeal nerve
D) Phrenic nerve
Explanation: The recurrent laryngeal nerve branches from the vagus nerve (cranial nerve X). On the right side, it loops around the subclavian artery. On the left side, it loops around the aortic arch. It innervates all intrinsic muscles of the larynx except the cricothyroid muscle, which is innervated by the external branch of the superior laryngeal nerve. Injury to the recurrent laryngeal nerve, such as during thyroid surgery or due to a tumor in the neck or mediastinum, can result in vocal cord paralysis. This can cause hoarseness, breathy voice, or even stridor if bilateral. Left-sided nerve palsy is more common due to the longer course of the left recurrent laryngeal nerve around the aortic arch. Compression by an aortic aneurysm or mediastinal tumors can cause symptoms.
Question 11: Which layer of the trachea contains the cartilage rings?
A) Mucosa
B) Submucosa
C) Adventitia
D) Muscularis
Explanation: The submucosa of the trachea contains the C-shaped cartilage rings that provide structural support to the trachea, preventing it from collapsing during respiration. Conditions like tracheomalacia can occur when the cartilage rings in the submucosa become weak or malformed, leading to tracheal collapse, especially during exhalation. This can cause difficulty breathing and wheezing. Mucosa (A): The innermost layer, consisting of pseudostratified ciliated columnar epithelium and a thin layer of connective tissue (lamina propria). It is responsible for trapping and moving particles out of the airway. Submucosa (B): Located beneath the mucosa, the submucosa contains mucus glands, blood vessels, and the C-shaped cartilage rings. Adventitia(C): The outermost layer that binds the trachea to surrounding structures, providing stability. Muscularis(D): This refers to the trachealis muscle, which connects the ends of the cartilage rings on the posterior aspect of the trachea and helps adjust the diameter of the trachea.
Question 12: How many generations of airway branching are there before the alveoli?
A) 10
B) 16
C) 23
D) 30
Explanation: The 23 generations of branching occur as follows: Trachea: The starting point of the airways, where the first division occurs into the left and right main bronchi. Main bronchi (1st generation): These split into secondary or lobar bronchi (2nd generation), which further divide into tertiary or segmental bronchi (3rd generation). Bronchioles: These are smaller airways that do not contain cartilage and continue to branch into even smaller bronchioles, known as terminal bronchioles. The final divisions after the 16th generation give rise to the respiratory bronchioles (17th generation) and the alveolar ducts (18th-23rd generations). Alveoli: The 23rd generation is the point where the alveolar sacs form, and gas exchange occurs through the thin walls of the alveoli.
Question 13: What type of cartilage forms the tracheal rings?
A) Elastic cartilage
B) Fibrocartilage
C) Hyaline cartilage
D) Calcified cartilage
Explanation: Hyaline cartilage is the most common type of cartilage in the body and is composed of a matrix with a high content of collagen fibers. This type of cartilage is smooth, flexible, and provides structural support without being as rigid as bone. Elastic cartilage is more flexible than hyaline cartilage and is found in structures that require elasticity, such as the epiglottis and external ear. Fibrocartilage is tougher and more resistant to compression, often found in areas that withstand high pressure, such as in the intervertebral discs and pubic symphysis. Calcified cartilage is cartilage that has been infiltrated with calcium salts, and while it is part of the developmental process of bone, it is not a major component of the adult trachea.
Question 14: Which of the following is NOT part of the upper airway?
A) Nasopharynx
B) Oropharynx
C) Trachea
D) Larynx
Explanation: The trachea is not part of the upper airway; it is considered part of the lower airway. The upper airway consists of structures responsible for the passage of air to the lower respiratory tract. It includes the nasopharynx, oropharynx, and larynx. The lower airway begins at the trachea.
Question 15: What is the primary function of goblet cells in the airway?
A) Secrete mucus to trap particles
B) Produce surfactant
C) Clear mucus via ciliary action
D) Generate cartilage
Explanation: Goblet cells are mucus-producing cells located in the epithelial lining of the airways, particularly in the trachea and bronchi. These cells are a type of unicellular gland and are named for their goblet-like shape when viewed under a microscope.
Question 16: Which part of the airway is responsible for warming and humidifying inspired air?
A) Nasal cavity
B) Trachea
C) Bronchioles
D) Alveoli
Explanation: The nasal cavity contains a highly vascularized area, which allows for the warming of the incoming air to body temperature. This is important because air that is too cold could damage the respiratory tract and decrease the efficiency of gas exchange in the lungs. The mucous membranes lining the nasal cavity secrete moisture, which humidifies the air before it reaches the lungs. This helps prevent the drying out of the delicate respiratory tissues in the lower airways and ensures that the air entering the alveoli is properly moistened, optimizing gas exchange. The nasal cavity also plays an important role in filtering out dust, bacteria, and other airborne particles through the mucous membranes and the cilia that line the nasal passages.
Question 17: What anatomical landmark is used to perform a cricothyrotomy?
A) Thyrohyoid membrane
B) Cricoid cartilage
C) Cricothyroid membrane
D) Tracheal rings
Explanation: The cricothyroid membrane is a flexible, thin membrane located between the cricoid cartilage and the thyroid cartilage in the neck. It serves as a crucial site for accessing the trachea in cases of airway obstruction or respiratory distress when other methods of securing the airway (such as intubation) are not possible. A cricothyrotomy involves making an incision through the cricothyroid membrane to insert a tube directly into the trachea. This allows for direct ventilation and is typically done in situations where there is an acute upper airway obstruction or severe trauma. Although cricothyrotomy is a life-saving procedure, there are potential complications, including bleeding, damage to surrounding structures, such as the vocal cords or thyroid gland, and infection.
Question 18: Which of the following structures forms the anterior wall of the larynx?
A) Thyroid cartilage
B) Cricoid cartilage
C) Epiglottis
D) Hyoid bone
Explanation: The thyroid cartilage is the largest cartilage in the larynx and is located at the front of the neck. It is composed of two laminae that meet at the midline to form the laryngeal prominence, commonly known as the Adam's apple. It provides a rigid structure that helps maintain the shape of the larynx and protects the more delicate structures inside, including the vocal cords. The thyroid cartilage serves as an attachment site for muscles and ligaments that control the movement of the vocal cords, allowing for speech, swallowing, and breathing.
Question 19: What is the functional unit of gas exchange in the lungs?
A) Alveoli
B) Bronchioles
C) Terminal bronchioles
D) Respiratory ducts
Explanation: The alveoli are tiny, sac-like structures located at the end of the respiratory bronchioles. They are surrounded by a network of capillaries, where the exchange of gases (oxygen and carbon dioxide) occurs. The walls of the alveoli are extremely thin, allowing for the efficient diffusion of gases between the alveolar air and the blood in the capillaries. This is the primary site where oxygen from inhaled air diffuses into the blood, and carbon dioxide from the blood is exhaled into the alveolar space.
Question 20: Which of the following marks the end of the conducting zone of the airway?
A) Terminal bronchioles
B) Respiratory bronchioles
C) Alveolar ducts
D) Alveoli
Explanation: The conducting zone starts at the nose and includes the nasal cavity, pharynx, larynx, trachea, bronchi, and bronchioles. The terminal bronchioles represent the end of the conducting zone because they are the last airway structures that do not participate in gas exchange. The respiratory bronchioles, which come after the terminal bronchioles, mark the beginning of the respiratory zone, where gas exchange begins. Respiratory bronchioles contain alveoli, which are the functional units of the lung involved in gas exchange.
Question 21: Which structure forms the roof of the nasal cavity?
A) Nasal septum
B) Cribriform plate
C) Palatine
D) Vomer
Explanation: The roof of the nasal cavity is formed by the cribriform plate, which is a thin, sieve-like structure located at the base of the ethmoid bone. The cribriform plate separates the nasal cavity from the cranial cavity and provides a passage for the olfactory nerves (CN I). These nerves pass through small holes in the cribriform plate to reach the olfactory bulb, which is located in the cranial cavity. The olfactory bulb is responsible for processing the sense of smell. Damage to the cribriform plate can lead to anosmia (loss of the sense of smell). The cribriform plate is located near the ethmoid sinuses, which are among the paranasal sinuses. In cases of sinus infections (e.g., ethmoid sinusitis), the infection can spread to the cribriform plate, potentially affecting the olfactory nerves.The palatine bone (option c) is located in the posterior part of the hard palate, contributing to the floor of the nasal cavity, not the roof.
Question 22: What is the primary blood supply to the trachea?
A) Subclavian arteries
B) Inferior thyroid arteries
C) Bronchial arteries
D) Pulmonary arteries
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