Anatomy and Physiology I (BIO 2010)

Correct Answer C. Diaphragm

Explanation

The diaphragm is the primary muscle of inspiration, responsible for creating negative intrathoracic pressure that allows air to enter the lungs. Unlike accessory muscles, which assist during forced inspiration, the diaphragm functions in both normal and deep breathing. Accessory muscles, such as the scalene and sternocleidomastoid, are recruited when increased respiratory effort is needed.

Why Other Options Are Wrong

A. Scalene

The scalene muscles assist in inspiration by elevating the first and second ribs, helping to expand the thoracic cavity. They become more active during deep or labored breathing, such as in respiratory distress. Unlike the diaphragm, they are not involved in passive breathing.

B. Sternocleidomastoid

The sternocleidomastoid muscle aids inspiration by elevating the sternum and clavicle, increasing lung volume. It is particularly active during exertion or respiratory distress but does not function as a primary breathing muscle in normal respiration.

D. Trapezius

The trapezius muscle assists in stabilizing the shoulders and upper thorax during deep inhalation. It indirectly supports respiratory function by maintaining posture and allowing efficient use of the accessory muscles. However, it is not directly involved in normal passive inspiration.

Correct Answer B. Percussion

Explanation

Chest physiotherapy (CPT) involves percussion techniques, such as clapping or vibrating the chest wall, to help loosen and mobilize mucus in the lungs. This technique is particularly useful for patients with conditions like cystic fibrosis, bronchiectasis, or chronic bronchitis, where mucus clearance is impaired. It is often combined with postural drainage to enhance mucus removal.

Why Other Options Are Wrong

A. Hydration

Proper hydration helps thin mucus, making it easier to clear, but it is not a direct component of chest physiotherapy. Hydration is a supportive measure rather than a technique used in CPT itself.

C. Nebulization

Nebulization delivers medications like bronchodilators or mucolytics to the lungs, but it does not involve mechanical mucus clearance techniques like percussion. It can be used in conjunction with CPT but is not a form of physiotherapy itself.

D. Humidification

Humidification helps prevent airway dryness and maintains mucus mobility, but it does not actively mobilize secretions like percussion does. While it is important in respiratory therapy, it is not considered a component of chest physiotherapy.

Correct Answer D. Covers ~95% of alveolar surface

Explanation

Type II pneumocytes are responsible for surfactant production and can proliferate into type I pneumocytes when needed. However, they do not cover 95% of the alveolar surface—this function belongs to type I pneumocytes, which form the thin epithelial lining for gas exchange.

Why Other Options Are Wrong

A. Synthesize pulmonary surfactants

This statement is true. Type II pneumocytes are the primary source of surfactant, which prevents alveolar collapse and reduces surface tension.

B. Secrete cytokines

This statement is also true. Type II pneumocytes contribute to lung immunity by secreting cytokines, which help regulate inflammation and immune responses.

C. Proliferate into type I cells

Correct as well. Type II cells can differentiate into type I cells when alveolar damage occurs, helping in lung repair and regeneration.

Correct Answer D. The gel layer becomes more viscous, while the sol layer becomes thinner, hindering ciliary movement.

Explanation

The gel layer of the mucous blanket traps particles, while the sol layer allows cilia to move efficiently. When mucociliary transport is impaired, the gel layer thickens, making mucus harder to clear, while the sol layer thins, reducing ciliary movement. This combination results in mucus stagnation and an increased risk of airway infections and obstruction.

Why Other Options Are Wrong

A. The gel layer becomes thinner and less viscous, while the sol layer becomes thicker and more viscous.

This is incorrect because in impaired mucociliary transport, the gel layer typically thickens rather than thinning. If it became thinner, mucus clearance would actually improve, which is the opposite of what occurs in conditions like cystic fibrosis or chronic bronchitis.

B. The gel layer remains unchanged, but the sol layer becomes thicker and less able to facilitate ciliary movement.

Both layers are affected in mucociliary dysfunction. If only the sol layer thickened while the gel layer remained normal, cilia might still be able to move mucus effectively, but in reality, the gel layer also becomes too thick to transport properly.

C. Both layers become thicker, leading to improved mucociliary function.

Thickening of both layers does not improve mucociliary function; instead, it hinders it. Thick mucus is harder to move, and if the sol layer also becomes thicker, ciliary motion is further restricted, leading to mucus accumulation and airway congestion.

Correct Answer B. They produce surfactant to lower surface tension

Explanation

Type II alveolar cells play a crucial role in lung function by synthesizing and secreting pulmonary surfactant. This surfactant decreases surface tension within the alveoli, preventing their collapse and ensuring efficient gas exchange.

Why Other Options Are Wrong

A. They are responsible for gas exchange

Gas exchange is the primary function of type I alveolar cells, not type II cells. Type I cells form the thin walls of the alveoli, allowing oxygen and carbon dioxide to diffuse between the air and blood.

C. They help in the immune response

Although the lungs have immune defense mechanisms, type II alveolar cells are not primarily responsible for immunity. Alveolar macrophages play a key role in defending against infections.

D. They transport carbon dioxide

Type II alveolar cells do not directly transport carbon dioxide. Gas transport occurs via red blood cells and plasma, with exchange occurring at the alveolar-capillary interface.

Correct Answer C. Glycoproteins

Explanation

The mucous blanket in the tracheobronchial tree is primarily composed of glycoproteins, which help trap inhaled particles, pathogens, and debris. These glycoproteins, combined with water, create mucus that is moved out of the airways by ciliary action.

Why Other Options Are Wrong

A. Water

Water is an important component of mucus, but glycoproteins provide the necessary adhesive and protective functions. Water alone does not create the sticky consistency needed for trapping particles.

B. Lipids

Lipids are more commonly associated with cell membranes and surfactant production rather than mucus secretion. They do not play a major role in forming the mucous blanket.

D. DNA

DNA is not a primary component of mucus. However, it may be found in mucus when inflammatory cells break down during infection, but it is not part of normal mucus composition.

Correct Answer C. Chest physiotherapy combined with nebulized medications

Explanation

Cystic fibrosis leads to thick, sticky mucus buildup in the airways, making clearance difficult. Chest physiotherapy helps loosen and mobilize secretions, while nebulized medications (such as hypertonic saline or bronchodilators) thin mucus and improve airway clearance. Combining both therapies provides the best strategy to clear mucus and improve lung function.

Why Other Options Are Wrong

A. Only nebulized medications

Nebulized medications help thin mucus and open airways but are not sufficient on their own. Without a mechanical method to remove secretions, mucus may still accumulate, leading to infections and airway obstruction. Cystic fibrosis treatment requires a multi-faceted approach, including airway clearance techniques.

B. Only suctioning

Suctioning can remove secretions from the upper airways but is ineffective in mobilizing mucus from deeper within the lungs. Without chest physiotherapy, secretions may remain trapped in the lower respiratory tract, increasing the risk of lung infections. Additionally, frequent suctioning can cause airway irritation and discomfort.

D. Oxygen therapy combined with suctioning

While oxygen therapy may help with respiratory distress, it does not address the thick mucus buildup that characterizes cystic fibrosis. Suctioning alone is also insufficient to clear deep-seated secretions. The best approach is to combine physical mobilization techniques with medication to effectively clear mucus from the airways.

Correct Answer B. The epiglottis may not close properly, increasing the risk of aspiration into the lungs

Explanation

The epiglottis acts as a protective structure that prevents food and liquids from entering the airway during swallowing. If it fails to close properly, substances can enter the trachea and lungs, leading to aspiration pneumonia or choking.

Why Other Options Are Wrong

A. The epiglottis may become inflamed, leading to increased airflow

While inflammation can affect the epiglottis, it does not lead to increased airflow. Inflammation can actually obstruct the airway and make breathing more difficult.

C. The epiglottis will enhance the swallowing reflex, improving airway protection

If the epiglottis is not functioning properly, it does not enhance the swallowing reflex. Instead, it compromises airway protection, increasing the risk of aspiration.

D. The epiglottis will have no effect on respiratory health in this scenario

An improperly functioning epiglottis can have serious consequences for respiratory health, including aspiration pneumonia, airway obstruction, and breathing difficulties.

Correct Answer A. The mucous blanket would become thicker and more viscous, potentially impairing mucociliary transport.

Explanation

Hydration is essential for maintaining the proper consistency of mucus, allowing cilia to transport it effectively. When a person is dehydrated, mucus becomes thicker and stickier, making it harder for the cilia to move it up the airways. This can lead to mucus buildup, increasing the risk of respiratory infections and airway obstruction.

Why Other Options Are Wrong

B. The mucous blanket would become thinner, improving airflow through the airways.

Dehydration does not thin mucus; instead, it makes it more viscous. Thin mucus typically results from excessive hydration or certain medications, not dehydration.

C. The mucous blanket would remain unchanged, as it is not affected by hydration levels.

Mucus production and consistency are directly influenced by hydration. Dehydration reduces the water content of mucus, making it thicker and more difficult to clear.

D. The mucous blanket would increase in volume, enhancing its protective function.

Instead of increasing in volume, dehydration reduces mucus production, leading to drier, thicker secretions that impair clearance rather than enhancing protection.