Anatomy and Physiology I (BIO 2010)

Correct Answer C. Delivering exogenous surfactant therapy

Explanation

Exogenous surfactant therapy is used to treat surfactant deficiency, particularly in neonatal respiratory distress syndrome (NRDS). This therapy helps reduce alveolar surface tension, preventing alveolar collapse and improving gas exchange. It is most effective when administered soon after birth in preterm infants or in conditions where surfactant production is impaired.

Why Other Options Are Wrong

A. Administering bronchodilators

Bronchodilators help relax airway smooth muscles, but they do not address the root cause of surfactant deficiency. While they may be beneficial in obstructive lung diseases like asthma, they do not prevent alveolar collapse or restore normal lung compliance in surfactant-deficient conditions.

B. Providing supplemental oxygen

Oxygen therapy can improve blood oxygen levels but does not resolve the underlying issue of alveolar collapse due to surfactant deficiency. In severe cases, oxygen alone may not be sufficient and could even contribute to complications like oxygen toxicity if delivered at high concentrations for prolonged periods.

D. Increasing fluid intake

While adequate hydration is important for overall lung function, increasing fluid intake does not directly correct surfactant deficiency. In some cases, excessive fluids can worsen respiratory conditions by contributing to pulmonary edema and fluid buildup in the lungs.

Correct Answer C. Oxytocin

Explanation

Oxytocin is produced by the hypothalamus and stored in the posterior pituitary, from where it is released. It plays a crucial role in uterine contractions during childbirth and milk ejection during breastfeeding. Unlike the other hormones listed, oxytocin is not synthesized in the anterior pituitary.

Why Other Options Are Wrong

A. TSH (Thyroid-Stimulating Hormone)

TSH is secreted by the anterior pituitary and regulates the thyroid gland’s production of T3 and T4, which are essential for metabolism. It is a key hormone in the hypothalamic-pituitary-thyroid axis.

B. Growth Hormone (GH)

GH is produced by the anterior pituitary and stimulates growth, cell regeneration, and metabolism. It affects multiple organs, including muscles, bones, and the liver, where it promotes IGF-1 production.

D. FSH (Follicle-Stimulating Hormone)

FSH is secreted by the anterior pituitary and regulates reproductive functions in both males and females. It stimulates spermatogenesis in men and follicular development in women, playing a key role in fertility.

Correct Answer B. It leads to alveolar collapse, impaired gas exchange and causing respiratory failure.

Explanation

Surfactant reduces alveolar surface tension, preventing alveolar collapse and ensuring proper lung expansion. In conditions like neonatal respiratory distress syndrome (NRDS) and acute respiratory distress syndrome (ARDS), surfactant deficiency causes increased work of breathing, impaired oxygen exchange, and respiratory distress. Without surfactant, alveoli collapse upon exhalation, making it difficult for patients to maintain adequate ventilation.

Why Other Options Are Wrong

A. It increases lung compliance and facilitates gas exchange.

Surfactant deficiency actually decreases lung compliance, making the lungs stiffer and harder to expand. Without surfactant, the increased surface tension makes it more difficult for the alveoli to remain open, impairing normal gas exchange.

C. It enhances mucociliary transport, improving airway clearance.

Mucociliary transport involves the movement of mucus and trapped particles by cilia in the airways, which is not related to surfactant function. Surfactant is crucial for alveolar stability, but it does not directly influence mucus clearance.

D. It has no significant effect on lung function.

Surfactant deficiency has severe effects on lung function, leading to hypoxia, respiratory distress, and the need for mechanical ventilation. Without surfactant, breathing becomes extremely difficult, particularly in premature infants and patients with ARDS.

Correct Answer B. Lung compliance when the lungs are still

Explanation

Static compliance measures how easily the lungs expand in response to pressure without airflow occurring. It is determined by the elasticity of lung tissue and is useful in diagnosing restrictive lung diseases, where lung stiffness impairs expansion.

Why Other Options Are Wrong

A. Lung compliance during movement

Lung compliance during movement refers to dynamic compliance, which considers both lung elasticity and airway resistance. Static compliance specifically excludes airway flow factors.

C. Airway resistance during breathing

Airway resistance is a separate measure that assesses how much force is needed to move air through the respiratory tract. While compliance deals with lung tissue elasticity, airway resistance focuses on factors like bronchoconstriction and mucus obstruction.

D. Gas exchange efficiency in the alveoli

Gas exchange efficiency is assessed by measuring factors such as oxygen diffusion and alveolar-capillary membrane thickness. Static compliance does not evaluate gas exchange directly but rather how easily the lungs expand at a given pressure.

Correct Answer B. To line the thoracic cavity.

Explanation

The parietal pleura is the outer layer of the pleural membrane and lines the inner surface of the thoracic cavity. It helps maintain negative pressure within the pleural space, allowing smooth lung expansion and contraction during breathing.

Why Other Options Are Wrong

A. To cover the lungs directly.

The visceral pleura, not the parietal pleura, covers the lungs directly. The visceral pleura and parietal pleura together create the pleural cavity, which helps facilitate lung movement.

C. To facilitate gas exchange.

Gas exchange occurs in the alveoli, not within the pleural membranes. The pleura do not play a direct role in oxygen and carbon dioxide diffusion.

D. To produce surfactant.

Surfactant is produced by type II alveolar cells within the lungs, not the pleural membranes. Surfactant reduces alveolar surface tension to prevent lung collapse, whereas the pleura primarily functions in lung movement and protection.

Correct Answer C. Bronchioles and terminal bronchioles

Explanation

Non-cartilaginous airways lack rigid cartilage support and are primarily composed of smooth muscle, allowing them to regulate airflow dynamically. Bronchioles and terminal bronchioles play a key role in controlling airway resistance and gas distribution.

Why Other Options Are Wrong

A. Trachea and primary bronchi

These airways contain significant cartilage to maintain structure and keep the airway open. They do not rely on smooth muscle for support like non-cartilaginous airways do.

B. Bronchi and bronchioles

While bronchioles are non-cartilaginous, the bronchi contain cartilage. This mix makes this answer incorrect since only bronchioles and terminal bronchioles are fully non-cartilaginous.

D. Alveoli and alveolar ducts

Alveoli and alveolar ducts are part of the gas exchange region of the lungs, not airways. These structures are primarily involved in diffusion of oxygen and carbon dioxide rather than airway resistance or airflow regulation.

Correct Answer B. Remove the tube and attempt re-intubation while ensuring proper placement.

Explanation

Esophageal intubation results in a lack of effective ventilation, leading to hypoxia. The tube should be immediately removed, and re-intubation should be performed using proper technique while confirming placement via auscultation and capnography. Delayed correction increases the risk of severe hypoxia, cardiac arrest, and patient deterioration.

Why Other Options Are Wrong

A. Monitor the patient's vital signs and wait for further instructions.

Monitoring the patient's vital signs and waiting for further instructions would allow hypoxia to worsen, leading to rapid oxygen desaturation and potentially fatal complications. Waiting does not resolve the incorrect placement of the tube, and corrective action must be taken immediately. Without proper ventilation, the patient's condition will continue to decline, making re-intubation an urgent necessity.

C. Administer supplemental oxygen through the malpositioned tube.

Administering supplemental oxygen through the malpositioned tube is ineffective because the air will enter the stomach instead of the lungs. Oxygen delivery through an esophageal tube does not contribute to oxygenation of the blood, increasing the risk of gastric distension and aspiration. This can worsen respiratory failure rather than correcting the issue.

D. Continue ventilation through the esophagus until help arrive

Continuing ventilation through the esophagus until help arrives does not provide oxygen to the lungs and will lead to severe hypoxia. The correct response is to recognize the error immediately and take action to remove the tube. Ventilation must be redirected into the trachea to ensure effective gas exchange.

Correct Answer B. Abdominal muscles and internal intercostals

Explanation

Accessory muscles of expiration, including the abdominal muscles and internal intercostals, assist in forcibly expelling air from the lungs. These muscles become active during forced expiration, such as during exercise or in respiratory conditions like chronic obstructive pulmonary disease (COPD). Unlike passive expiration, which relies on lung recoil, these muscles contract to push air out more forcefully.

Why Other Options Are Wrong

A. Diaphragm and external intercostals

The diaphragm and external intercostals are primary muscles of inspiration, not expiration. The diaphragm contracts to create negative pressure for inhalation, while the external intercostals assist in expanding the rib cage.

C. Sternocleidomastoid and scalene muscles

These muscles are accessory muscles of inspiration, helping to elevate the rib cage during deep breathing. They are primarily recruited in conditions that require increased ventilatory effort, such as respiratory distress, but do not contribute to expiration.

D. Pectoralis major and minor

The pectoralis muscles primarily control upper limb movement and chest expansion. While they may assist in forced breathing under certain conditions, they are not classified as accessory expiratory muscles.

Correct Answer B. It prevents food and liquids from entering the airway.

Explanation

The epiglottis is a flap of cartilage that covers the opening of the trachea during swallowing. This prevents food and liquids from entering the airway, reducing the risk of aspiration pneumonia. It plays a critical role in ensuring that the respiratory and digestive systems function separately without interference.

Why Other Options Are Wrong

A. It allows air to pass freely into the trachea.

While the epiglottis opens during breathing to allow air passage, its primary function is to close off the airway during swallowing. Allowing free airflow is important, but this is not its main role in the swallowing process.

C. It aids in the production of sound.

The vocal cords, located in the larynx, are responsible for sound production, not the epiglottis. The epiglottis indirectly affects phonation by modifying airflow but does not directly generate sound.

D. It regulates airflow during breathing.

Airflow is primarily controlled by the trachea, bronchi, and bronchial smooth muscles, not the epiglottis. The epiglottis only temporarily alters airflow during swallowing, not as part of normal respiratory regulation.