BIOL 252 | BIOL252 Module 4: Human Anatomy &
Physiology II with Lab Updated and Latest
Questions and Correct Answers with Rationale -
Portage Learning
1. Which of the following structures is responsible for the production of surfactant within the
alveoli?
A. Type I alveolar cells
B. Type II alveolar cells
C. Alveolar macrophages
D. Goblet cells
Correct Answer: B
Explanation: Type II alveolar cells are cuboidal epithelial cells that secrete surfactant to
reduce surface tension. This reduction in surface tension prevents the alveoli from
collapsing during expiration. In contrast, Type I cells are thin and primarily responsible for
gas exchange. Alveolar macrophages serve an immune function by clearing debris from the
respiratory surface. Without sufficient surfactant, the work of breathing increases
significantly, leading to respiratory distress.
2. During inspiration, which of the following changes occurs in the thoracic cavity?
A. The diaphragm relaxes and moves upward.
B. The external intercostal muscles relax.
C. Intrapulmonary pressure becomes lower than atmospheric pressure.
D. The volume of the thoracic cavity decreases.
Correct Answer: C
Explanation: According to Boyle’s law, an increase in thoracic volume leads to a decrease
in intrapulmonary pressure. During inspiration, the diaphragm contracts and moves
inferiorly to expand the chest cavity. The external intercostals also contract to lift the ribs
and increase the lateral and anterior-posterior dimensions. When the pressure inside the
lungs drops below atmospheric pressure, air flows into the lungs. This process is an active
phase of ventilation requiring muscle energy.
3. A patient has an arterial PCO2 of 50 mmHg. Which of the following is the most likely
physiological response?
A. Decreased firing rate of the medullary rhythmicity center
B. Decreased stimulation of central chemoreceptors
,C. Hypoventilation to conserve oxygen
D. Increased rate and depth of breathing
Correct Answer: D
Explanation: An elevated PCO2 level, known as hypercapnia, stimulates both central and
peripheral chemoreceptors. These receptors detect the resulting increase in hydrogen ion
concentration in the cerebrospinal fluid and blood. The signals are sent to the medullary
respiratory centers to increase the rate and depth of ventilation. This compensatory
mechanism helps to ‘blow off’ excess carbon dioxide and restore normal pH levels.
Regulation of breathing is primarily driven by carbon dioxide levels rather than oxygen
levels under normal conditions.
4. Which factor would cause the oxyhemoglobin dissociation curve to shift to the right?
A. Decreased body temperature
B. Increased blood pH (alkalosis)
C. Increased partial pressure of carbon dioxide (PCO2)
D. Decreased 2,3-BPG levels
Correct Answer: C
Explanation: A rightward shift of the oxyhemoglobin dissociation curve indicates a
decreased affinity of hemoglobin for oxygen. This shift occurs in response to increased
PCO2, increased temperature, and decreased pH, known as the Bohr effect. These
conditions are typically found in metabolically active tissues that require more oxygen
delivery. By shifting the curve to the right, hemoglobin more readily unloads oxygen to the
tissues that need it most. Conversely, a leftward shift increases affinity and occurs in cooler,
more alkaline environments like the lungs.
5. How is the majority of carbon dioxide transported in the blood?
A. Dissolved directly in the plasma
B. Bound to the heme group of hemoglobin
C. As bicarbonate ions in the plasma
D. As carbaminohemoglobin within red blood cells
Correct Answer: C
Explanation: Approximately 70% of carbon dioxide is transported in the blood as
bicarbonate ions. Inside red blood cells, carbon dioxide reacts with water to form carbonic
acid, facilitated by the enzyme carbonic anhydrase. Carbonic acid then dissociates into
hydrogen ions and bicarbonate ions. The bicarbonate then moves out of the red blood cell
into the plasma in exchange for chloride. This mechanism provides an efficient way to
transport metabolic waste while also serving as a pH buffer.
, 6. What is the functional significance of the C-shaped cartilaginous rings in the trachea?
A. They allow the trachea to collapse completely during swallowing.
B. They prevent the trachea from collapsing during pressure changes of ventilation.
C. They facilitate the movement of food down the trachea.
D. They serve as the primary site for gas exchange in the upper airway.
Correct Answer: B
Explanation: The C-shaped tracheal cartilages provide structural rigidity to keep the
airway open at all times. This prevents the trachea from collapsing inward during the
negative pressure generated by inspiration. The open part of the ‘C’ faces the esophagus,
allowing it to expand slightly when food is swallowed. This anatomical arrangement
balances the need for a patent airway with the proximity of the digestive tract. Without
these rings, the airway would be prone to obstruction and increased resistance.
7. Which volume represents the amount of air inhaled or exhaled during a normal, quiet
breath?
A. Residual Volume
B. Tidal Volume
C. Inspiratory Reserve Volume
D. Vital Capacity
Correct Answer: B
Explanation: Tidal volume is the volume of air that moves into and out of the lungs during
a single resting respiratory cycle. In a healthy adult, this volume is typically around 500
milliliters. It represents the baseline ventilation needed to maintain gas exchange at rest.
Other volumes like inspiratory reserve represent the extra air that can be inhaled with
effort. Monitoring changes in tidal volume is important in assessing respiratory health and
lung function.
8. Which of the following correctly describes the chloride shift?
A. Chloride ions bind to hemoglobin to increase its affinity for carbon dioxide.
B. Chloride moves out of the RBC to allow oxygen to bind to hemoglobin.
C. Chloride moves into the RBC as bicarbonate moves out to maintain electrical neutrality.
D. Chloride moves into the alveoli to help dissolve surfactant.
Correct Answer: C
Explanation: The chloride shift occurs when bicarbonate ions diffuse out of the red blood
cell and into the plasma. To maintain electrical balance, chloride ions move from the
plasma into the red blood cell. This process happens in systemic capillaries where CO2
Physiology II with Lab Updated and Latest
Questions and Correct Answers with Rationale -
Portage Learning
1. Which of the following structures is responsible for the production of surfactant within the
alveoli?
A. Type I alveolar cells
B. Type II alveolar cells
C. Alveolar macrophages
D. Goblet cells
Correct Answer: B
Explanation: Type II alveolar cells are cuboidal epithelial cells that secrete surfactant to
reduce surface tension. This reduction in surface tension prevents the alveoli from
collapsing during expiration. In contrast, Type I cells are thin and primarily responsible for
gas exchange. Alveolar macrophages serve an immune function by clearing debris from the
respiratory surface. Without sufficient surfactant, the work of breathing increases
significantly, leading to respiratory distress.
2. During inspiration, which of the following changes occurs in the thoracic cavity?
A. The diaphragm relaxes and moves upward.
B. The external intercostal muscles relax.
C. Intrapulmonary pressure becomes lower than atmospheric pressure.
D. The volume of the thoracic cavity decreases.
Correct Answer: C
Explanation: According to Boyle’s law, an increase in thoracic volume leads to a decrease
in intrapulmonary pressure. During inspiration, the diaphragm contracts and moves
inferiorly to expand the chest cavity. The external intercostals also contract to lift the ribs
and increase the lateral and anterior-posterior dimensions. When the pressure inside the
lungs drops below atmospheric pressure, air flows into the lungs. This process is an active
phase of ventilation requiring muscle energy.
3. A patient has an arterial PCO2 of 50 mmHg. Which of the following is the most likely
physiological response?
A. Decreased firing rate of the medullary rhythmicity center
B. Decreased stimulation of central chemoreceptors
,C. Hypoventilation to conserve oxygen
D. Increased rate and depth of breathing
Correct Answer: D
Explanation: An elevated PCO2 level, known as hypercapnia, stimulates both central and
peripheral chemoreceptors. These receptors detect the resulting increase in hydrogen ion
concentration in the cerebrospinal fluid and blood. The signals are sent to the medullary
respiratory centers to increase the rate and depth of ventilation. This compensatory
mechanism helps to ‘blow off’ excess carbon dioxide and restore normal pH levels.
Regulation of breathing is primarily driven by carbon dioxide levels rather than oxygen
levels under normal conditions.
4. Which factor would cause the oxyhemoglobin dissociation curve to shift to the right?
A. Decreased body temperature
B. Increased blood pH (alkalosis)
C. Increased partial pressure of carbon dioxide (PCO2)
D. Decreased 2,3-BPG levels
Correct Answer: C
Explanation: A rightward shift of the oxyhemoglobin dissociation curve indicates a
decreased affinity of hemoglobin for oxygen. This shift occurs in response to increased
PCO2, increased temperature, and decreased pH, known as the Bohr effect. These
conditions are typically found in metabolically active tissues that require more oxygen
delivery. By shifting the curve to the right, hemoglobin more readily unloads oxygen to the
tissues that need it most. Conversely, a leftward shift increases affinity and occurs in cooler,
more alkaline environments like the lungs.
5. How is the majority of carbon dioxide transported in the blood?
A. Dissolved directly in the plasma
B. Bound to the heme group of hemoglobin
C. As bicarbonate ions in the plasma
D. As carbaminohemoglobin within red blood cells
Correct Answer: C
Explanation: Approximately 70% of carbon dioxide is transported in the blood as
bicarbonate ions. Inside red blood cells, carbon dioxide reacts with water to form carbonic
acid, facilitated by the enzyme carbonic anhydrase. Carbonic acid then dissociates into
hydrogen ions and bicarbonate ions. The bicarbonate then moves out of the red blood cell
into the plasma in exchange for chloride. This mechanism provides an efficient way to
transport metabolic waste while also serving as a pH buffer.
, 6. What is the functional significance of the C-shaped cartilaginous rings in the trachea?
A. They allow the trachea to collapse completely during swallowing.
B. They prevent the trachea from collapsing during pressure changes of ventilation.
C. They facilitate the movement of food down the trachea.
D. They serve as the primary site for gas exchange in the upper airway.
Correct Answer: B
Explanation: The C-shaped tracheal cartilages provide structural rigidity to keep the
airway open at all times. This prevents the trachea from collapsing inward during the
negative pressure generated by inspiration. The open part of the ‘C’ faces the esophagus,
allowing it to expand slightly when food is swallowed. This anatomical arrangement
balances the need for a patent airway with the proximity of the digestive tract. Without
these rings, the airway would be prone to obstruction and increased resistance.
7. Which volume represents the amount of air inhaled or exhaled during a normal, quiet
breath?
A. Residual Volume
B. Tidal Volume
C. Inspiratory Reserve Volume
D. Vital Capacity
Correct Answer: B
Explanation: Tidal volume is the volume of air that moves into and out of the lungs during
a single resting respiratory cycle. In a healthy adult, this volume is typically around 500
milliliters. It represents the baseline ventilation needed to maintain gas exchange at rest.
Other volumes like inspiratory reserve represent the extra air that can be inhaled with
effort. Monitoring changes in tidal volume is important in assessing respiratory health and
lung function.
8. Which of the following correctly describes the chloride shift?
A. Chloride ions bind to hemoglobin to increase its affinity for carbon dioxide.
B. Chloride moves out of the RBC to allow oxygen to bind to hemoglobin.
C. Chloride moves into the RBC as bicarbonate moves out to maintain electrical neutrality.
D. Chloride moves into the alveoli to help dissolve surfactant.
Correct Answer: C
Explanation: The chloride shift occurs when bicarbonate ions diffuse out of the red blood
cell and into the plasma. To maintain electrical balance, chloride ions move from the
plasma into the red blood cell. This process happens in systemic capillaries where CO2
