Anatomy and Physiology I (BIO 2010)

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 B. Shortness of breath

Explanation

A mediastinal mass pressing on the trachea can narrow the airway, making it difficult for air to pass through. This results in dyspnea (shortness of breath), stridor, and in severe cases, respiratory distress. The degree of breathing impairment depends on the size and location of the mass.

Why Other Options Are Wrong

A. Increased appetite

A mediastinal mass typically does not affect appetite. Conditions affecting appetite are usually related to gastrointestinal function, metabolic disorders, or hormonal imbalances rather than airway compression.

C. Decreased heart rate

A tracheal compression does not directly lower heart rate. However, if severe respiratory distress occurs, oxygen deprivation can affect heart function, potentially leading to an increased heart rate rather than a decrease.

D. Improved lung function

Tracheal compression restricts airflow and can lead to reduced oxygen intake, making lung function worse, not better. Patients may experience stridor, difficulty breathing, and even hypoxia in severe cases.

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. Pulmonary circulation is affected, resulting in reduced oxygen uptake and increased carbon dioxide levels in the blood.

Explanation

A pulmonary embolism (PE) occurs when a blood clot obstructs the pulmonary arteries, reducing blood flow to the lungs. This blockage prevents proper oxygenation of blood, leading to hypoxemia and respiratory distress. Additionally, carbon dioxide removal is impaired, which can result in respiratory acidosis.

Why Other Options Are Wrong

A. Systemic circulation is affected, leading to decreased oxygen delivery to tissues.

While a PE indirectly affects systemic oxygen delivery, the primary issue is within the pulmonary circulation. Oxygen uptake is impaired in the lungs before it can affect systemic circulation.

C. Both circulations are equally affected, causing overall respiratory failure.

While severe cases of PE can contribute to respiratory failure, systemic circulation is not equally affected. Pulmonary circulation is the primary site of obstruction, and systemic effects occur secondary to hypoxia.

D. Only the heart's pumping ability is affected, with no impact on gas exchange.

Although a PE can strain the heart, especially the right ventricle, its main effect is impaired gas exchange. If untreated, a PE can cause right heart failure, but the immediate problem is oxygenation failure in the lungs.

Correct Answer A. Hormonal

Explanation

Hormonal regulation occurs when one hormone stimulates another gland to release its hormones. For example, thyroid-stimulating hormone from the pituitary gland stimulates the thyroid gland to release T3 and T4. This type of control is a key part of the hypothalamic-pituitary-thyroid axis.

Why Other Options Are Wrong

B. Humoral regulation involves direct responses to blood levels of certain ions or nutrients, such as calcium or glucose. An example is the secretion of insulin in response to blood glucose levels, which does not involve stimulating hormones. Unlike hormonal regulation, humoral mechanisms rely on chemical changes in the bloodstream rather than endocrine gland interactions.

C. Synthetic regulation is not a recognized biological mechanism. While synthetic hormones can be administered medically, hormone secretion in the body is regulated by natural feedback mechanisms. Hormonal responses involve endocrine signaling, not artificially induced changes.

D. Neural regulation involves direct nervous system control over hormone release, such as the release of epinephrine from the adrenal medulla due to sympathetic nervous stimulation. The thyroid gland is regulated hormonally, not directly by neural signals. Neural input can influence hormone secretion, but it does not govern thyroid function directly.

Correct Answer B. It prevents the alveoli from collapsing, allowing for easier lung expansion.

Explanation

Surfactant reduces surface tension in the alveoli, preventing their collapse during exhalation and making lung expansion easier. This function is particularly crucial in newborns, as a deficiency in surfactant can lead to neonatal respiratory distress syndrome. By stabilizing alveoli, surfactant ensures efficient gas exchange and reduces the work of breathing.

Why Other Options Are Wrong

A. It increases the effort required for inhalation.

Surfactant actually decreases the effort required for inhalation by reducing surface tension. Without surfactant, the alveoli would collapse more easily, making it much harder for the lungs to expand.

C. It enhances the diffusion of gases across the alveolar membrane.

Surfactant does not directly affect gas diffusion; rather, it prevents alveolar collapse, which indirectly supports consistent oxygen-carbon dioxide exchange. Gas diffusion depends more on alveolar membrane thickness and partial pressure gradients.

D. It regulates the temperature of the air entering the lungs.

Surfactant does not influence air temperature. The warming of air occurs in the nasal passages and upper respiratory tract, where blood vessels help condition inhaled air before it reaches the lungs.

Correct Answer C. They nourish the lungs and associated structures, ensuring proper function and health.

Explanation

The bronchial arteries arise from the aorta and supply oxygenated blood to the lung tissues, including the bronchi, pleura, and connective tissues. Unlike the pulmonary arteries, which carry deoxygenated blood for gas exchange, bronchial arteries provide direct nourishment to lung structures. This dual blood supply ensures that the lungs receive adequate oxygenation and nutrients to maintain normal function.

Why Other Options Are Wrong

A. They supply oxygenated blood to the lungs and support gas exchange.

While the bronchial arteries do supply oxygenated blood to lung tissues, they do not participate in gas exchange. Gas exchange occurs in the alveoli via the pulmonary circulation, not through bronchial artery perfusion.

B. They provide nutrients to the alveoli and enhance surfactant production.

Alveolar cells receive oxygen primarily through the pulmonary circulation, not the bronchial arteries. Surfactant production is regulated by type II alveolar cells, and while they require nourishment, the bronchial arteries do not directly enhance surfactant production.

D. They are responsible for draining deoxygenated blood from the lungs.

Deoxygenated blood from lung tissues is drained by the bronchial veins and pulmonary veins, not the bronchial arteries. Bronchial arteries are part of the systemic circulation, whereas venous drainage is handled by separate pathways.

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. Questionnaire

Explanation

Richard and Mulenga (2019) used a questionnaire-based approach to collect data on energy drink consumption and its effects on sleep quality. This method allowed participants to self-report their intake, sleep patterns, and related behaviors, providing a broad dataset for analysis. Questionnaires are widely used in sleep research to assess subjective sleep quality and lifestyle factors.

Why Other Options Are Wrong

A. Observational study involves researchers directly observing participants over a period of time rather than relying on self-reported data. While this method can provide detailed behavioral insights, it was not the approach used in this study. Instead, a questionnaire allowed for data collection from a larger sample.

C. Interviews involve face-to-face or structured conversations where researchers collect qualitative data. While interviews provide detailed insights, they are time-consuming and typically used for smaller sample sizes. The study by Richard and Mulenga (2019) used a structured questionnaire to gather quantitative data instead.

D. Focus groups involve small participant discussions to explore shared experiences and perspectives. While useful for gathering in-depth insights, focus groups do not generate broad, structured data as questionnaires do. The study relied on self-reported measures rather than group-based discussions.