NEW
Font size
WorksheetsRespiratory Physiology Worksheet Extraction
Total questions: 80
Worksheet time: 40mins
A 25-year-old medical student participates in a charity run. During heavy exercise, which muscles are used for active expiration?
Diaphragm and external intercostals
Diaphragm and internal intercostals
Internal intercostals and abdominal recti
Scaleni and sternocleidomastoid
A premature infant (28 weeks) develops cyanosis and labored breathing. A deficiency in which substance increases surface tension and causes alveolar collapse?
Albumin
Dipalmitoylphosphatidylcholine
Mucus
Carbonic anhydrase
If the transpulmonary pressure is 5 cm H2O and the lung volume increases by 1.0 liter, what is the lung compliance?
0.1 L/cm H2O
0.2 L/cm H2O
0.5 L/cm H2O
1.0 L/cm H2O
Which pressure is defined as the pressure in the thin space between the lung visceral pleura and the chest wall parietal pleura?
Alveolar pressure
Pleural pressure
Transpulmonary pressure
Transthoracic pressure
In a saline‑filled lung, the compliance is much greater than in an air‑filled lung because:
Saline reduces tissue elasticity
Saline removes the air‑fluid interface/surface tension
Saline increases the secretion of surfactant
Saline decreases the recoil of elastic fibers
A patient with emphysema has high lung compliance. This is primarily due to:
Increased surfactant production
Destruction of alveolar septa and elastic fibers
Increased thickness of the respiratory membrane
Reduced airway resistance
Which muscle is considered the primary muscle of inspiration in a healthy adult at rest?
Internal intercostals
Abdominal recti
Diaphragm
Serratus anterior
During inspiration, the pleural pressure becomes:
More positive
More negative
Equal to atmospheric pressure
Zero
The work of breathing is increased in "Restrictive" lung diseases primarily because of an increase in:
Airway resistance work
Compliance work
Tissue resistance work
Surface tension work
What is the normal value of alveolar pressure during the middle of a quiet expiration?
−1 cm H2O
+1 cm H2O
0 cm H2O
+5 cm H2O
A 22‑year‑old woman has a tidal volume (VT) of 500 mL, a residual volume (RV) of 1200 mL, and an expiratory reserve volume (ERV) of 1100 mL. What is her functional residual capacity (FRC)?
1600 mL
2300 mL
2800 mL
3300 mL
Which of the following lung volumes cannot be measured by a simple spirometer?
Tidal volume
Vital capacity
Functional residual capacity
Inspiratory reserve volume
A patient has a vital capacity of 4.5 L and a total lung capacity of 6.0 L. What is their residual volume?
1.0 L
1.5 L
2.0 L
2.5 L
In an obstructive lung disease like chronic bronchitis, the FEV1/FVC ratio is typically:
>0.85
0.80
<0.70
Normal
A 70‑year‑old man with pulmonary fibrosis has a low FVC but a normal or high FEV1/FVC ratio. This is characteristic of:
Obstructive lung disease
Restrictive lung disease
Normal aging
Asthma
The volume of air that remains in the lungs after a maximal forceful expiration is the:
Functional residual capacity
Residual volume
Expiratory reserve volume
Dead space
If a person has a respiratory rate of 15 breaths/min and a tidal volume of 500 mL, what is their minute respiratory volume?
6.0 L/min
7.5 L/min
5.0 L/min
10.0 L/min
Physiological dead space is equal to anatomical dead space in:
Healthy individuals
Patients with emphysema
Patients with pneumonia
Patients with pulmonary edema
A patient with a tidal volume of 600 mL and a dead space of 150 mL has a breathing frequency of 10/min. The alveolar ventilation rate is:
6000 mL/min
4500 mL/min
7500 mL/min
1500 mL/min
Which capacity is defined as the maximum amount of air a person can expel from the lungs after first filling the lungs to their maximum extent?
Inspiratory capacity
Functional residual capacity
Vital capacity
Total lung capacity
In "Zone 3" of the lung (lower parts), blood flow is continuous because:
Alveolar pressure is always higher than arterial pressure
Arterial and venous pressures remain higher than alveolar pressure
Alveolar pressure is zero
Gravity decreases capillary pressure
Which factor causes the most significant increase in pulmonary arterial pressure during heavy exercise?
Massive increase in left atrial pressure
Large increase in cardiac output
Sympathetic vasoconstriction
Decreased lung compliance
What is the normal mean pulmonary arterial pressure?
10 mmHg
15 mmHg
25 mmHg
5 mmHg
Pulmonary edema is most likely to occur when the pulmonary capillary hydrostatic pressure exceeds:
7 mmHg
15 mmHg
28 mmHg
40 mmHg
A patient with mitral stenosis develops left‑sided heart failure. Which pressure rise is the immediate precursor to pulmonary edema?
Right atrial pressure
Left atrial pressure
Pulmonary vein pressure
Both B and C
The shift of blood from the lungs to the systemic circulation occurs during:
Exercise
Blowing a trumpet (high intrathoracic pressure)
Deep inspiration
Lying down
What is the physiological purpose of "hypoxic pulmonary vasoconstriction"?
To increase overall lung blood flow
To shunt blood away from poorly ventilated alveoli
To increase systemic oxygenation
To prevent pulmonary edema
Pleural effusion (excess fluid in the pleural space) can be caused by:
Blockage of lymphatic drainage
Heart failure
Reduced plasma colloid osmotic pressure
All of the above
The "safety factor" against pulmonary edema is approximately:
5 mmHg
14 mmHg
21 mmHg
30 mmHg
Pulmonary capillaries are unique because they:
Are surrounded by air on all sides
Are very thick to prevent rupture
Only carry deoxygenated blood
Do not allow any filtration
The rate of diffusion of a gas across the respiratory membrane is inversely proportional to:
Surface area of the membrane
Partial pressure gradient
Thickness of the membrane
Solubility of the gas
Why is the diffusion capacity of CO2 much higher than that of O2?
CO2 has a lower molecular weight
CO2 has a much higher solubility coefficient
CO2 has a higher pressure gradient
CO2 binds more strongly to hemoglobin
The partial pressure of oxygen (PO2) in humidified tracheal air (at 37°C) is approximately:
159 mmHg
149 mmHg
104 mmHg
40 mmHg
The average PO2 of blood entering the pulmonary capillaries (venous blood) is:
100 mmHg
40 mmHg
46 mmHg
95 mmHg
Which of the following makes up the "respiratory membrane"?
Alveolar epithelium and capillary endothelium
Surfactant layer
Interstitial space
All of the above
During exercise, the diffusion capacity for O2 increases because:
Capillaries dilate and previously dormant capillaries open
The respiratory membrane becomes thinner
Hemoglobin concentration increases
The heart rate decreases
The partial pressure of CO2 in the alveoli is primarily determined by:
Rate of CO2 excretion and rate of alveolar ventilation
Atmospheric PCO2
Thickness of the membrane
Solubility of CO2
Alveolar PO2 is usually 104 mmHg. Why is systemic arterial PO2 only about 95 mmHg?
Diffusion is incomplete
Shunt blood (bronchial circulation) mixes with oxygenated blood
O2 is consumed by the capillary endothelium
Errors in measurement
In a person standing upright, the ventilation‑perfusion (V/Q) ratio is highest at the:
Base of the lung
Apex of the lung
Middle of the lung
Hilum
A V/Q ratio of zero indicates:
Physiological dead space
Physiological shunt (no ventilation)
Normal gas exchange
Perfect ventilation
Most oxygen is transported in the blood:
Dissolved in plasma
As bicarbonate
Bound to hemoglobin
Bound to albumin
The Bohr Effect refers to the shift of the O2–Hb dissociation curve to the right in response to:
Increased pH
Increased CO2 and H+ ions
Decreased temperature
Decreased 2,3-DPG
What is the PO2 at which hemoglobin is 50% saturated (P50)?
40 mmHg
27 mmHg
100 mmHg
60 mmHg
Most CO2 (about 70%) is transported in the blood as:
Dissolved CO2
Carbaminohemoglobin
Bicarbonate ions
Carbonic acid
The Chloride Shift (Hamburger phenomenon) involves the movement of chloride ions into the RBC in exchange for:
Oxygen
Bicarbonate ions
Sodium ions
Potassium ions
The Haldane Effect describes how:
CO2 shifts the O2 curve
Binding of O2 with Hb tends to displace CO2 from the blood
CO binds more strongly to Hb than O2
Temperature affects O2 binding
Carbon monoxide (CO) is dangerous because:
It shifts the O2–Hb curve to the right
It binds to Hb with 250 times the affinity of O2
It dissolves easily in plasma
It stimulates the chemoreceptors directly
What happens to the O2–Hb curve at high altitudes?
Shifts to the left
Shifts to the right (due to increased 2,3-DPG)
Becomes flat
No change
Utilization Coefficient is defined as the:
Percentage of blood that gives up its oxygen as it passes through tissues
Total volume of O2 in blood
Rate of O2 consumption by cells
Solubility of O2
During resting conditions, how many milliliters of O2 are delivered to the tissues per 100 mL of blood?
20 mL
5 mL
15 mL
1.34 mL
The primary chemosensitive area in the medulla is most directly stimulated by:
O2
CO2
Hydrogen ions (H+)
Nitrogen
Peripheral chemoreceptors (carotid and aortic bodies) are most sensitive to changes in:
Arterial PCO2
Arterial PO2 (below 60 mmHg)
Blood pH
CO concentration
The Hering-Breuer Inflation Reflex helps prevent:
Hypoxia
Over-inflation of the lungs
Alveolar collapse
Hypercapnia
Cheyne-Stokes breathing is a type of periodic breathing characterized by:
Rapid breathing due to metabolic acidosis
Waxing and waning of respiration with periods of apnea
Deep gasps followed by expiration
Totally irregular breathing
Obstructive sleep apnea is most commonly associated with:
Damage to the respiratory center
Obesity and airway obstruction by the tongue/soft palate
High altitude
Lack of surfactant
The Pneumotaxic Center in the upper pons primarily functions to:
Stimulate inspiration
Switch off inspiration (limit inspiration duration)
Monitor CO2 levels
Control the diaphragm
What is the most potent stimulus for the central chemoreceptors?
A drop in arterial PO2
A rise in arterial PCO2
A rise in arterial pH
Exercise
In a patient with chronic COPD, the respiratory drive may become dependent on:
CO2 levels
Low O2 levels (hypoxic drive)
High pH
Lung stretch receptors
Acclimatization to low PO2 at high altitude involves:
Increased RBC count (polycythemia)
Increased vascularity of tissues
Increased ventilation
All of the above
The Dorsal Respiratory Group (DRG) is primarily responsible for:
Basic rhythm of inspiration
Forced expiration
Pneumotaxic control
Swallowing
A 45-year-old male with a history of deep vein thrombosis suddenly develops chest pain and shortness of breath. Diagnosis: pulmonary embolism. What happens to the V/Q ratio in the affected area?
It becomes zero
It becomes infinite (dead space)
It remains 0.8
It decreases
A victim of a fire is brought to the ER. Despite a normal arterial PO2, the patient is cyanotic and has cherry-red skin. This is classic for:
Carbon dioxide poisoning
Carbon monoxide poisoning
Cyanide poisoning
Oxygen toxicity
A patient with severe kyphoscoliosis (deformed chest wall) will show which pattern on spirometry?
Decreased FEV1/FVC ratio
Decreased vital capacity and total lung capacity
Increased residual volume
Normal compliance
A 6-year-old child with an acute asthma attack is wheezing. The physiological cause of the wheeze is:
Increased lung compliance
Decreased airway radius (increased resistance)
Pulmonary edema
Decreased surfactant
Mountain sickness (headache, nausea) at high altitudes is primarily due to:
Low PCO2
Hypoxia and cerebral vasodilation
Nitrogen narcosis
High O2 levels
Nitrogen Narcosis occurs in deep-sea divers because:
Nitrogen becomes more soluble at high pressure
Nitrogen is toxic to the lungs
Oxygen levels are too low
Carbon dioxide builds up
A person hyperventilates for 1 minute. Why do they often experience a period of apnea immediately afterward?
O2 levels are too high
CO2 levels have dropped below the threshold to stimulate breathing
The diaphragm is tired
pH has become acidic
A patient has a PaO2 of 50 mmHg and a PaCO2 of 60 mmHg. This condition is:
Respiratory alkalosis
Respiratory acidosis with hypoxia
Metabolic acidosis
Normal
Which factor would cause the O2–Hb dissociation curve to shift to the left?
High altitude
Fetal hemoglobin (HbF)
High temperature
High 2,3-DPG
A patient in a coma has a breathing pattern of deep, rapid breaths (Kussmaul breathing). This is usually due to:
Sleep apnea
Metabolic acidosis (e.g., diabetic ketoacidosis)
Brainstem stroke
Pulmonary embolism
The A–a gradient (alveolar–arterial O2 difference) increases in:
Hypoventilation
High altitude
Diffusion defects (e.g., fibrosis)
Normal breathing
The term Hypercapnia refers to:
Low O2 in blood
High CO2 in blood
High pH
Rapid breathing
In the fetus, the lungs are filled with fluid. The first breath requires very high negative pressure to overcome:
Surface tension in the collapsed alveoli
Thick mucus
Low chest wall compliance
High venous pressure
The solubility of oxygen in plasma is:
0.003 mL/100mL/mmHg
0.03 mL/100mL/mmHg
0.3 mL/100mL/mmHg
3.0 mL/100mL/mmHg
Decompression Sickness (the bends) is caused by the formation of bubbles of:
Oxygen
Carbon dioxide
Nitrogen
Helium
The pressure required to keep an alveolus open is inversely proportional to its radius (Law of Laplace). This explains why:
Large alveoli collapse more easily
Small alveoli would collapse into large ones without surfactant
Surfactant is unnecessary for small alveoli
Compliance is constant
Which of the following is a component of the Work of Breathing?
Compliance work
Tissue resistance work
Airway resistance work
All of the above
During quiet breathing, expiration is a passive process because of:
Diaphragm contraction
Elastic recoil of the lungs
Surfactant activation
Gravity
Chronic high-altitude exposure leads to an increase in 2,3-DPG. This results in:
Easier loading of O2 in lungs
Easier unloading of O2 to the tissues
Decreased RBC production
Left shift of the curve
Alveolar ventilation is more effective at increasing oxygenation than increasing respiratory rate because:
It reduces anatomical dead space
It overcomes the wasted air in the dead space
It prevents surfactant depletion
It decreases CO2 solubility
