BIOL 252 MODULE 7 EXAM– QUESTIONS AND ANSWERS |
VERIFIED AND WELL DETAILED ANSWERS PLUS RATIONALES |
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1. Which of the following anatomical structures marks the transition point where the upper
respiratory tract ends and the lower respiratory tract begins?
A. Nasopharynx
B. Larynx
C. Trachea
D. Carina
ANSWER: B. Larynx
The larynx serves as the anatomical landmark separating the upper respiratory tract from the
lower respiratory tract. The nasopharynx is strictly part of the upper system, while the trachea
and carina belong entirely to the lower system.
2. A patient presents with labored breathing characterized by prolonged expiration and
wheezing, primarily due to increased resistance within the conducting zone. Which
component of the bronchial tree is primarily responsible for regulating this resistance
through bronchoconstriction?
A. Main bronchi
B. Lobar bronchi
C. Bronchioles
D. Alveolar ducts
ANSWER: C. Bronchioles
Bronchioles possess thick rings of smooth muscle in their walls relative to their diameter,
lacking cartilage support, which enables them to actively alter lumen diameter and airflow
resistance via autonomic nervous control.
3. During a routine physical examination, a physician notes that a patient's resting tidal
volume is approximately 500 mL, and their respiratory rate is 12 breaths per minute. What
,is the approximate alveolar ventilation rate if the anatomical dead space is estimated at 150
mL?
A. 1,800 mL/min
B. 4,200 mL/min
C. 6,000 mL/min
D. 7,800 mL/min
ANSWER: B. 4,200 mL/min
Alveolar ventilation rate accounts for dead space air and is calculated by subtracting the dead
space volume from tidal volume, then multiplying by the respiratory rate: $(500\ \text{mL} -
150\ \text{mL}) \times 12\ \text{breaths/min} = 4,200\ \text{mL/min}$.
4. A researcher measures the partial pressures of gases in a healthy individual at sea level.
If the atmospheric pressure is 760 mmHg and oxygen constitutes approximately 21% of
dry atmospheric air, what is the partial pressure of oxygen (PO2) in dry air?
A. 100 mmHg
B. 150 mmHg
C. 159.6 mmHg
D. 600 mmHg
ANSWER: C. 159.6 mmHg
According to Dalton's law of partial pressures, the partial pressure of a gas equals the total
pressure multiplied by its fractional concentration: $760\ \text{mmHg} \times 0.21 = 159.6\
\text{mmHg}$.
5. Which specialized alveolar cell type is primarily responsible for secreting pulmonary
surfactant to reduce surface tension and prevent alveolar collapse?
A. Type I alveolar cells
B. Type II alveolar cells
C. Alveolar macrophages
D. Dust cells
,ANSWER: B. Type II alveolar cells
Type II alveolar cells secrete surfactant, a complex lipoprotein mixture that decreases surface
tension in the fluid lining alveoli. Type I cells form the thin respiratory membrane, while
macrophages provide immune defense.
6. A clinical patient sustains a traumatic chest wall injury, resulting in a puncture that
allows air to enter the intrapleural space. What immediate physiological consequence
occurs within the affected pleural cavity?
A. Intrapleural pressure becomes positive relative to atmospheric pressure, causing lung
collapse.
B. Intrapleural pressure becomes increasingly negative, causing hyperinflation.
C. Transpulmonary pressure increases sharply, stabilizing the lung.
D. Surface tension within the alveoli disappears entirely.
ANSWER: A. Intrapleural pressure becomes positive relative to atmospheric pressure,
causing lung collapse.
Normally, intrapleural pressure is negative relative to atmospheric pressure, keeping lungs
expanded. A puncture introduces air (pneumothorax), equalizing pressures and eliminating
the transpulmonary pressure gradient, leading to atelectasis (collapse).
7. Which brainstem respiratory center establishes the baseline eupneic rhythm of quiet
breathing by driving motor output to the diaphragm and external intercostal muscles?
A. Pneumotaxic center
B. Apneustic center
C. Ventral respiratory group
D. Dorsal respiratory group
ANSWER: D. Dorsal respiratory group
The dorsal respiratory group (DRG) located in the medulla oblongata acts as the primary
integrator for respiratory rhythm, sending regular impulses to the diaphragm. The ventral
group handles forced breathing, while pontine centers modulate rate and depth.
8. An arterial blood gas (ABG) analysis of a climber at high altitude reveals a low arterial
PCO2 due to hyperventilation. What immediate effect does this hypocapnia have on the pH
of the cerebrospinal fluid and subsequent respiratory drive?
, A. CSF pH increases (alkalosis), which inhibits ventilation.
B. CSF pH decreases (acidosis), which stimulates ventilation.
C. CSF pH remains completely unchanged due to robust renal compensation.
D. CSF sodium levels shift to normalize ventilation.
ANSWER: A. CSF pH increases (alkalosis), which inhibits ventilation.
Hyperventilation blows off CO2, decreasing blood and CSF hydrogen ion concentrations,
which raises pH (alkalosis). Central chemoreceptors detect this rise in pH and reduce the
respiratory drive to restore homeostasis.
9. When oxygen binds to a hemoglobin molecule, it induces a conformational change that
increases the affinity of the remaining subunits for subsequent oxygen molecules. What
term describes this physiological property?
A. Competitive inhibition
B. Cooperative binding
C. Allosteric saturation
D. Bohr effect
ANSWER: B. Cooperative binding
Cooperative binding describes how the binding of the first oxygen molecule alters
hemoglobin's quaternary structure, making it progressively easier for subsequent oxygen
molecules to bind, resulting in a sigmoid dissociation curve.
10. During heavy exercise, metabolically active skeletal muscles experience a drop in pH,
an increase in temperature, and elevated PCO2 levels. How do these physiological shifts
alter the oxygen-hemoglobin dissociation curve?
A. Shift the curve to the left, increasing oxygen affinity.
B. Shift the curve to the right, promoting oxygen unloading to tissues.
C. Shift the curve downward without altering position.
D. Completely halt hemoglobin oxygen binding.
ANSWER: B. Shift the curve to the right, promoting oxygen unloading to tissues.
VERIFIED AND WELL DETAILED ANSWERS PLUS RATIONALES |
GUARANTEED PASS | LATEST EXAM UPDATE | EXAM PREP |
STUDY GUIDE | PRACTICE TEST| DOWNLOAD INSTANT PDF
1. Which of the following anatomical structures marks the transition point where the upper
respiratory tract ends and the lower respiratory tract begins?
A. Nasopharynx
B. Larynx
C. Trachea
D. Carina
ANSWER: B. Larynx
The larynx serves as the anatomical landmark separating the upper respiratory tract from the
lower respiratory tract. The nasopharynx is strictly part of the upper system, while the trachea
and carina belong entirely to the lower system.
2. A patient presents with labored breathing characterized by prolonged expiration and
wheezing, primarily due to increased resistance within the conducting zone. Which
component of the bronchial tree is primarily responsible for regulating this resistance
through bronchoconstriction?
A. Main bronchi
B. Lobar bronchi
C. Bronchioles
D. Alveolar ducts
ANSWER: C. Bronchioles
Bronchioles possess thick rings of smooth muscle in their walls relative to their diameter,
lacking cartilage support, which enables them to actively alter lumen diameter and airflow
resistance via autonomic nervous control.
3. During a routine physical examination, a physician notes that a patient's resting tidal
volume is approximately 500 mL, and their respiratory rate is 12 breaths per minute. What
,is the approximate alveolar ventilation rate if the anatomical dead space is estimated at 150
mL?
A. 1,800 mL/min
B. 4,200 mL/min
C. 6,000 mL/min
D. 7,800 mL/min
ANSWER: B. 4,200 mL/min
Alveolar ventilation rate accounts for dead space air and is calculated by subtracting the dead
space volume from tidal volume, then multiplying by the respiratory rate: $(500\ \text{mL} -
150\ \text{mL}) \times 12\ \text{breaths/min} = 4,200\ \text{mL/min}$.
4. A researcher measures the partial pressures of gases in a healthy individual at sea level.
If the atmospheric pressure is 760 mmHg and oxygen constitutes approximately 21% of
dry atmospheric air, what is the partial pressure of oxygen (PO2) in dry air?
A. 100 mmHg
B. 150 mmHg
C. 159.6 mmHg
D. 600 mmHg
ANSWER: C. 159.6 mmHg
According to Dalton's law of partial pressures, the partial pressure of a gas equals the total
pressure multiplied by its fractional concentration: $760\ \text{mmHg} \times 0.21 = 159.6\
\text{mmHg}$.
5. Which specialized alveolar cell type is primarily responsible for secreting pulmonary
surfactant to reduce surface tension and prevent alveolar collapse?
A. Type I alveolar cells
B. Type II alveolar cells
C. Alveolar macrophages
D. Dust cells
,ANSWER: B. Type II alveolar cells
Type II alveolar cells secrete surfactant, a complex lipoprotein mixture that decreases surface
tension in the fluid lining alveoli. Type I cells form the thin respiratory membrane, while
macrophages provide immune defense.
6. A clinical patient sustains a traumatic chest wall injury, resulting in a puncture that
allows air to enter the intrapleural space. What immediate physiological consequence
occurs within the affected pleural cavity?
A. Intrapleural pressure becomes positive relative to atmospheric pressure, causing lung
collapse.
B. Intrapleural pressure becomes increasingly negative, causing hyperinflation.
C. Transpulmonary pressure increases sharply, stabilizing the lung.
D. Surface tension within the alveoli disappears entirely.
ANSWER: A. Intrapleural pressure becomes positive relative to atmospheric pressure,
causing lung collapse.
Normally, intrapleural pressure is negative relative to atmospheric pressure, keeping lungs
expanded. A puncture introduces air (pneumothorax), equalizing pressures and eliminating
the transpulmonary pressure gradient, leading to atelectasis (collapse).
7. Which brainstem respiratory center establishes the baseline eupneic rhythm of quiet
breathing by driving motor output to the diaphragm and external intercostal muscles?
A. Pneumotaxic center
B. Apneustic center
C. Ventral respiratory group
D. Dorsal respiratory group
ANSWER: D. Dorsal respiratory group
The dorsal respiratory group (DRG) located in the medulla oblongata acts as the primary
integrator for respiratory rhythm, sending regular impulses to the diaphragm. The ventral
group handles forced breathing, while pontine centers modulate rate and depth.
8. An arterial blood gas (ABG) analysis of a climber at high altitude reveals a low arterial
PCO2 due to hyperventilation. What immediate effect does this hypocapnia have on the pH
of the cerebrospinal fluid and subsequent respiratory drive?
, A. CSF pH increases (alkalosis), which inhibits ventilation.
B. CSF pH decreases (acidosis), which stimulates ventilation.
C. CSF pH remains completely unchanged due to robust renal compensation.
D. CSF sodium levels shift to normalize ventilation.
ANSWER: A. CSF pH increases (alkalosis), which inhibits ventilation.
Hyperventilation blows off CO2, decreasing blood and CSF hydrogen ion concentrations,
which raises pH (alkalosis). Central chemoreceptors detect this rise in pH and reduce the
respiratory drive to restore homeostasis.
9. When oxygen binds to a hemoglobin molecule, it induces a conformational change that
increases the affinity of the remaining subunits for subsequent oxygen molecules. What
term describes this physiological property?
A. Competitive inhibition
B. Cooperative binding
C. Allosteric saturation
D. Bohr effect
ANSWER: B. Cooperative binding
Cooperative binding describes how the binding of the first oxygen molecule alters
hemoglobin's quaternary structure, making it progressively easier for subsequent oxygen
molecules to bind, resulting in a sigmoid dissociation curve.
10. During heavy exercise, metabolically active skeletal muscles experience a drop in pH,
an increase in temperature, and elevated PCO2 levels. How do these physiological shifts
alter the oxygen-hemoglobin dissociation curve?
A. Shift the curve to the left, increasing oxygen affinity.
B. Shift the curve to the right, promoting oxygen unloading to tissues.
C. Shift the curve downward without altering position.
D. Completely halt hemoglobin oxygen binding.
ANSWER: B. Shift the curve to the right, promoting oxygen unloading to tissues.
