Respiratory System MCQs


# During inspiration when the diaphragm contracts, the intrapleural pressure becomes:
A. More negative
B. Less negative
C. Positive
D. Equal to the intra-alveolar pressure

# A decrease in the arterial pO2 is seen in:

A. Decrease in hemoglobin concentration of arterial blood
B. Paralysis of inspiratory muscles
C. Sluggish blood flow
D. High altitudes


# The major sign of hypoventilation is:

A. Cyanosis
B. Dyspnoea
C. Hypercapnia
D. Hypoxia

# Tidal volume in an adult is :

A. 125 ml
B. 500 ml
C. 1500 ml
D. 2200 ml

# Most effective method of assessing breathing is by measuring:

A. Tidal volume
B. Respiratory rate
C. Alveolar ventilation
D. FEV1

# The volume of gas in the lungs at the end of normal expiration is:

A. Expiratory reserve volume
B. Functional residual capacity
C. Residual volume
D. Inspiratory reserve volume

# Oxygen dissociation curve shifts to the right by all of the following except:

A. Rise in temperature
B. Rise in carbon dioxide tension
C. Rise in pH
D. Rise in H+ ion

# The type of hypoxia present in high altitude is:

A. Anemic hypoxia
B. Hypoxic hypoxia
C. Stagnant hypoxia
D. Histotoxic hypoxia


# The best stimulator of the respiratory center is:

A. Decrease in arterial carbon dioxide level
B. Increase in arterial carbon dioxide level
C. Increase in arterial oxygen level
D. None of the above

# Vital capacity is decreased, timed vital capacity (FEV 1.0%) is normal in:

A. Bronchial asthma
B. Scoliosis
C. Chronic bronchitis
D. Acute bronchitis

# What effect does hyperventilation have on the oxygen binding capacity of hemoglobin?

A. P50 and oxygen affinity decrease
B. P50 and oxygen affinity increase
C. P50 decreases and the oxygen affinity increases
D. P50 increases and the oxygen affinity decreases
# Surfactant is secreted by:
A. Pneumocyte I
B. Pneumocyte II
C. Goblet cells
D. Pulmonary vessels

# During the initial part of inspiration, which of the following does not occur ?
A. Intrapulmonary pressure falls
B. Intrathoracic pressure rises
C. Intraabdominal pressure rises
D. The partial pressure of O2 in dead space rises

# Alveolar O2 tension is :
A. Increased by hyperventilation
B. Decreased by hyperventilation
C. Similar to venous O2 tension
D. Not affected by respiratory depression

# Cyanosis or bluish coloration of skin and mucus membrane depends upon :
A. The relative proportion of reduced and oxygenated hemoglobin
B. The absolute amount of reduced hemoglobin
C. Thickness of the skin
D. Fragility of the capillaries

# Hypoxia is characterized by :
A. Low arterial pO2
B. Intense chemoreceptor response
C. Favourable response to 100 % oxygen
D. All of the above
# Limitation of inspiration by vagal lung inflation signals is called the:
A. Autonomic reflex
B. Bainbridge reflex
C. Hering-Breur reflex
D. Dynamic stretch reflex

# The intrapleural pressure at the end of deep inspiration is :
A. -4 mm of Hg
B. +4 mm of Hg
C. -18 mm of Hg
D. +18 mm of Hg

# Smoking causes :
A. Ciliary motility
B. Cellular hyperplasia
C. Mucous secretion
D. Allof the above

# The alveolar ventilation in an individual with tidal volume 600 ml, dead space 150 ml and respiratory rate of 15/minute is :
A. 2.5 liter/min
B. 4.0 liter/min
C. 6.75 liter/min
D. 9.0 liter/min

# Non- respiratory function of the lung is :
A. Dopamine metabolism
B. Adrenaline metabolism
C. Serotonin metabolism
D. PGE2 production

# Oxygen dissociation curve is shifted to the right in all except :
A. Fall in pH
B. Rise in temperature
C. Increase in 2,3 DPG
D. HbF

# Oxygen affinity is increased by all except :
A. Alkalosis
B. Hypoxia
C. Increased HbF
D. Hypothermia

# Muscle of expiration is :
A. Diaphragm
B. External intercostals
C. Internal intercostals
D. Recti abdominis

# Arterial O2 content is reduced in one of the following :
A. Stagnant hypoxia
B. Anemic hypoxia
C. Histotoxic hypoxia
D. Hypoxic or arterial hypoxia
# In which of the following diseases would you expect to find an increase in thickness of the respiratory membrane ?
A. Emphysema
B. Asthma
C. Pulmonary artery thrombosis
D. Skeletal abnormalities of the chest

# Oxygen affinity decreases in:
A. Hypoxia
B. Hypothermia
C. HbF
D. Increased pH

# Arterial pO2 is reduced in :
A. Anemia
B. KCN poisoning
C. Pulmonary hypoventilation
D. CO poisoning

# Vital capacity is a measure of :
A. Tidal volume
B. Inspiratory reserve volume plus expiratory reserve volume
C. Tidal volume plus inspiratory reserve volume plus expiratory reserve volume
D. Expiratory reserve volume plus residual volume

# Which of the following does not stimulate alveolar hyperventilation ?
A. Hypoxia
B. Hypercapnia
C. Acidosis
D. Stretching of airways

# Ventilation perfusion ratio is maximum in :
A. Base of lung
B. Apex of lung
C. Posterior lobe of lung
D. Middle lobe of lung

# The most common form of hypoxia is :
A. Hypoxic
B. Stagnant
C. Anemic
D. Histotoxic

# Increase in partial pressure of CO2 leading to release of oxygen to the tissues is :
A. Haldane effect
B. Bohr effect
C. Breur effect
D. Hamburger effect

# In Haldane effect , CO2 distribution curve is shifted to :
A. Left
B. Right
C. Does not shift
D. None of the above

# Which of the following statements regarding pulmonary surfactant is false ?
A. It is secreted by type II pneumocytes
B. It contains lecithin and sphingomyelin
C. It increases surface tension
D. It prevents collapse of small alveoli

# The oxygen tension of mixed venous blood is :
A. 25 mm of Hg
B. 40 mm of Hg
C. 55 mm of Hg
D. 70 mm of Hg

# At high altitudes the following changes take place except :
A. Increase in respiratory rate
B. Increase in depth of respiration
C. Increase in oxygen carrying capacity of blood
D. Increase in partial pressure of CO2
# Kussmaul's respiration occurs in response to :
A. Decrease in pH of blood
B. Increase in pH of blood
C. Obstructive pulmonary jaundice
D. Carbon monoxide poisoning

# Shift of the oxygen dissociation curve to the right is caused by all of the following factors except :
A. Increased 2,3 BPG
B. Increased temperature
C. Increased concentration of carbon dioxide
D. Increased concentration of oxygen

# Energy expenditure during normal breathing is :
A. 25-50% of total energy spent
B. 50-75% of total energy spent
C. 15-20% of total energy spent
D. 2-3% of total energy spent

# The work of breathing :
A. is inversely related to lung compliance
B. remains constant during exercise
C. is not affected by respiratory rate
D. decreases in lying posture

# What is true about pneumothorax ?
A. Total chest wall diameter is increased
B. Intrapleural pressure becomes more negative
C. The concentration of surfactant is reduced in alveoli
D. Increased lung compliance

# Oxygen as an emergency drug is contraindicated in :
A. Anaphylaxis
B. Asthma
C. Hyperventilation
D. COPD

# The approximate amount of air left in the lungs after maximal forced expiration in a normal woman is :
A. 0.5 L
B. 2.0 L
C. 1.1 L
D. 1.8 L

# The transport of CO is diffusion limited because :
A. Binds avidly with Hb
B. Partial pressure of CO is less
C. CO is less absorbed in water
D. Alveolar membrane is less permeable

# Inability of exchange of oxygen through lung tissue is known as :
A. Anoxic anoxia
B. Anoxia
C. Histotoxic hypoxia
D. Ischemic hypoxia

# Carotid body function in an organ work as :
A. Differential pressure of oxygen in arterial blood
B. Differential pressure of oxygen in venous blood
C. Differential pressure of oxygen in tissue fluids
D. Differential pressure of oxygen in hemoglobin synthesis
# The exchange of gases between plasma and tissue fluid is a function of :
A. Partial pressures
B. Hydrostatic pressures
C. Osmotic pressure differentials
D. Difference in volume percent of gases

# Circulatory shock is an example of :
A. Hypoxic hypoxia
B. Stagnant hypoxia
C. Histotoxic hypoxia
D. Anemic hypoxia

# Oxyhemoglobin saturation does not depend upon :
A. Temperature
B. Fetal hemoglobin and adult hemoglobin ratio
C. Skin color
D. 2,3 DPG

# Within the RBC, hypoxia stimulates glycolysis by which of the following regulating pathways ?
A. Hypoxia stimulates pyruvate dehydrogenase by increased 2,3 DPG
B. Hypoxia inhibits hexokinase
C. Hypoxia stimulates release of all glycolytic enzymes from band 3 on RBC membrane
D. Activation of the regulatory enzymes by high pH



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