Respiratory physiology Flashcards
Consider the following statements regarding functional residual capacity (FRC).
It can be measured using a spirometer
False. Measurement requires helium dilution of total body plethysmography.
Consider the following statements regarding functional residual capacity (FRC).
It increases with age
True. FRC continues to increase with age as the elastic recoil of the lungs deteriorates
Consider the following statements regarding functional residual capacity (FRC).
It is 10% lower in women than men of similar height
True
Consider the following statements regarding functional residual capacity (FRC).
It is unaffected by pregnancy
False. As the gravid uterus pushes the diaphragm cephalad, FRC is reduced, as is the extra weight of the breast on the chest wall.
Consider the following statements regarding functional residual capacity (FRC).
It is equal to residual volume + expiratory reserve volume
True
Consider the following statements regarding physiological dead space
It is smaller than anatomical dead space
False. Physiological dead space = anatomical dead space + alveolar dead space.
Consider the following statements regarding physiological dead space
It is increased by pulmonary embolism
True
Consider the following statements regarding physiological dead space
It can be increased if tidal volume drops despite an increase in respiratory rate
True. A smaller proportion of the tidal volume reaches the alveoli.
Consider the following statements regarding physiological dead space
It is measured using Fowler’s method
False. Fowler’s method is used to measure anatomical dead space. The Bohr equation calculates physiological dead space.
Consider the following statements regarding physiological dead space
Calculation requires knowledge of arterial partial pressure of CO2
True. The Bohr equation requires PACO2 and PECO2 to calculate the dead space to tidal volume ratio.
Consider the following statements regarding functional residual capacity.
Helium dilution gives a larger estimation than body plethysmography
False. Plethysmography gives a larger, more accurate estimation of FRC, especially in diseased lungs where gas trapping may occur.
Consider the following statements regarding functional residual capacity.
Changes in FRC can affect pulmonary vascular resistance
True. Normally, FRC is at the point where PVR is least, but a decrease in FRC may cause an increase in PVR.
Consider the following statements regarding functional residual capacity.
FRC increases in asthma
True. Obstructive lung disease can cause gas trapping.
Consider the following statements regarding functional residual capacity.
FRC increases with PEEP
True
Consider the following statements regarding functional residual capacity.
FRC increases following administration of neuromuscular blocking agents
False. Anything that decreases muscle tone of the diaphragm and intercostal muscles will reduce FRC.
Consider the following statements regarding dead space.
It increases while snorkelling
True. The snorkel acts as an increase in the transporting airway.
Consider the following statements regarding dead space.
If increased, it leads to hypoxia
False. Dead space per se is not a cause of hypoxia.
Consider the following statements regarding dead space.
It accounts for the difference in arterial and expired CO2 concentrations
True
Consider the following statements regarding dead space.
It increases with bronchodilatation and neck extension
True
Consider the following statements regarding dead space.
Alveolar dead space decreases with age
False
The functional residual capacity
is increased in the obese
False
The functional residual capacity
is approx 10% higher in men than women
False
The functional residual capacity
falls with general anaesthesia
True
The functional residual capacity
increases when changing from supine to standing
True
The functional residual capacity
falls with increasing age
False
Vital capacity is the volume or air expired from full inspiration to full expiration
True
Vital capacity increases gradually with age in adults
False
Vital capacity is greater in men than women of a similar age and height
True
Vital capacity is equal to the sum of the inspiratory and expiratory reserve volumes
False
Vital capacity may be measured by spirometry
True
Closing Capacity is larger than functional reserve capacity
False
Closing Capacity may be determined by single breath N2 curve following deep breath of O2
False
Closing Capacity is high in young children and decreases progressively with age
False
Closing Capacity if high may be responsible for arterial hypoxaemia
True
Closing Capacity is unaffected by bronchomotor tone
False
Closing volume increases with age
True
Closing volume decreases with anaesthesia
True
Closing volume is increased in the upright position
false
Closing volume is increased in obesity
false
Closing volume can be measured using single breath nitrogen technique
True
FRC can be measured using Helium wash in
True
FRC can be measured using nitrogen was out
True
FRC can be measured using body plethysmography
True
FRC can be measured using spirometry
false
FRC can be measured using intra-oesophaeal balloon
False
Surfactant is a mucopolypeptide
False
Surfactant causes a decrease in surface tension
true
Surfactant equilibrates surfae tension for different sized alveoli
true
Surfactant causes an increase in compliance
true
Surfactant production is reduced after a prolonged reduction in pulmonary blood flow
True
pulmonary surfactant is a mixture of phospholipids and proteins
True
pulmonary surfactant causes and increase in chest wall compliance
false
pulmonary surfactant prevents transudation or fluid from the blood into the alveoli
true
pulmonary surfactant deficiencies in babies born to diabetic mothers is due to fetal hyperinulinism
true
pulmonary surfactant concentration per unit area is directly proportional to surface tension
false
When the V/Q ratio of a lung unit increases the alveolar PO2 rises
true
When the V/Q ratio of a lung unit increases the alveolar CO2 rises
False
When the V/Q ratio of a lung unit increases end capillary PO2 rises
true
When the V/Q ratio of a lung unit increases arterial PO2 increases
True
When the V/Q ratio of a lung unit increases hypoxic pulmonary vasoconstriction will compensate for any change in gas exchange
false
The distribution of ventilation of an upright subject is related to regional airways diameters
True
The distribution of ventilation of an upright subject is related to regional differences in compliance
True
The distribution of ventilation of an upright subject is related to inspired O2 concentration
false
The distribution of ventilation of an upright subject is related to gravitational forces in the lung
True
The distribution of ventilation of an upright subject is related to intrathoracic pressure
True
In an awake, healthy individual in the lateral position, the dependant lung has less ventilation
false
In an awake, healthy individual in the lateral position, the dependant lung has more perfusion
true
In an awake, healthy individual in the lateral position, the V/Q ratio is higher in the dependant lung
false
In an awake, healthy individual in the lateral position, the PACO2 is lower in the lower lung
false
In an awake, healthy individual in the lateral position, the PAO2 is higher in the lower lung
false
The following vessels are important in the physiological shunt Bronchial veins
true
The following vessels are important in the physiological shunt Thebesian veins
true
The following vessels are important in the physiological shunt coronary sinus
false
The following vessels are important in the physiological shunt ductus venosus
false
The following vessels are important in the physiological shunt azygous veins
false
An area in the lung with increased V/Q ratio represents dead space
true
An area in the lung with increased V/Q ratio represents shunt
false
An area in the lung with increased V/Q ratiois responsible for a decrease in the PAO2 with no change in PACO2
false
An area in the lung with increased V/Q ratio will cause a degree of hypoxia
false
An area in the lung with increased V/Q ratio may be compensated for by an increase minute ventilation
true
A pressure volume curve can be used for measuring the owrk of breathing
true
A pressure volume curve can be used for measuring functional residual capacity
false
A pressure volume curve can be used for measuring anatomical dead space
false
A pressure volume curve can be used for measuring compliance
true
A pressure volume curve can be used for measuring respiratory quotient
false
body plethysmography can be used to measure compliance
true
body plethysmography can be used to measure work of breathing
true
body plethysmography can be used to measure gas exchange
false
body plethysmography can be used to measure airway resistance
true
body plethysmography can be used to measure FEV1
false
concerning lung volumes and capacities the total volume of both lungs is the vital capacity
false
concerning lung volumes and capacities closing capacity is the sum of the closing volume and the FRC
false
concerning lung volumes and capacities the volume which may be forcibly exhaled in 1 sec is greater than 85% of the vital capacity
false
concerning lung volumes and capacities the FRC can be measured with a spirometer
false
concerning lung volumes and capacities the sum of the insp reserve volume and the exp reserve volume is the vital capacity
false
Alveolar dead space exceeds tidal volume at rest
false
Alveolar ventilation decreases as tidal volume increases
false
Alveolar partial pressure of water vapour exceeds that of carbon dioxide
true
Alveolar patial pressure of O2 falls within an increase in physiological dead space
false
Alveolar O2 uptake exceeds alveolar carbon dioxide output
true
Breathing spontaneously in the lateral position:
Perfusion is greater in the dependent lung
True.
Breathing spontaneously in the lateral position:
Ventilation is decreased in the uppermost lung
True.
Breathing spontaneously in the lateral position:
V/Q is higher in the dependent lung
False. In the awake adult, ventilation and perfusion are greater in the lower (dependent) lung although perfusion is slightly better than ventilation and so V/Q < 1.
Breathing spontaneously in the lateral position:
Dependent lung has a lower PO2
True. V/Q is < 1, ie there is a degree of shunt. In areas of shunt alveolar gas tends toward mixed venous so PAO2 is low and PACO2 slighlty raised.
Breathing spontaneously in the lateral position:
Non-dependent lung has a higher PCO2
False. In the non-dependent lung V/Q > 1, ie a degree of dead space. Alveolar gas now tends toward inspired gas and so PO2 is raised but PCO2 is low.
FRC can be measured using:
Body plethysmography
True
FRC can be measured using:
Nitrogen wash-out
True
FRC can be measured using:
Spirometry
False
FRC can be measured using:
Helium wash-in
True
FRC can be measured using:
Intra-oesophageal balloon
False. Intra-oesophageal balloons are used to measure intra-pleural pressure.
Concerning 2,3, DPG:
It binds the beta chains of deoxyhaemoglobin
True.
Concerning 2,3, DPG:
It is formed from a product of glycolysis
True. 2,3-DPG is formed in red blood cells from phosphoglyceraldehyde, a product of glycolysis.
Concerning 2,3, DPG:
An increased concentration increases oxygen utilisation by cells
True. 2,3 DPG shifts the O2 dissociation curve to the right, reducing oxygen binding to haemoglobin and thus increasing oxygen availability for tissue utilization.
Concerning 2,3, DPG:
Its red cell concentration is increased by circulating thyroid hormones
True. Thyroid hormones, along with growth hormone and angrogens increase 2,3,DPG concentration.
Concerning 2,3, DPG:
Is strongly bound by fetal haemoglobin
False. Fetal Hb does not contain beta chains.
Dipalmitoylphosphatidylcholine:
Is a mucopolypeptide
False. It is a phospholipid, found in lung surfactant.
Dipalmitoylphosphatidylcholine:
Causes an increase in surface tension
False. Surfactants role is to decrease surface tension.
Dipalmitoylphosphatidylcholine:
Causes an increase in chest wall compliance
False. It increases lung compliance, not chest wall compliance.
Dipalmitoylphosphatidylcholine:
Production is reduced in low cardiac output states
True. As it is derived from free fatty acids carried in the blood stream.
Dipalmitoylphosphatidylcholine:
Maintains the same surface tension for different sized alveoli
False. It is more effective at reducing surface tension in small alveoli. This reduces the effect of Laplace’s law, which would otherwise cause small alveoli to collape.
Peripheral chemoreceptors:
Are found in the carotid sinus
False. They are located in the carotid and aortic bodies.
Peripheral chemoreceptors:
Are downregulated in the presence of chronic lung disease
False. Central chemoreceptors in the medulla respond to a rise in PaCO2 and CSF pH.
Peripheral chemoreceptors:
Are stimulated by elevated levels of carboxyhaemoglobin
False.
Peripheral chemoreceptors:
Give rise to increased afferent signals when PaO2 falls below 13 kPa
True. The carotid body is the prime O2 sensory organ.
Peripheral chemoreceptors:
Maintain PaCO2 within the range 4.5-6.0 kPa
False. see part D.
Carbon dioxide:
Freely diffuses across the blood : brain barrier
True. Unlike H+ ions and HCO3-.
Carbon dioxide:
Is lagely transported unchanged
False. Most is transported as bicarbonate. Around 5% is transported unchanged in the blood.
Carbon dioxide:
Gives rise to the same pH change in CSF as it does in blood
False. pH changes are greater in the CSF due to the lack of buffers.
Carbon dioxide:
Transport by haemoglobin is inhibited by rising oxygen saturation
True. By the Haldane effect.
Carbon dioxide:
Has direct sympathomimetic activity
False. But it does increase activation of the sympathetic system.
Pulmonary blood flow:
Is normally less than the cardiac output
True. A small proportion of the cardiac output will be anatomical shunt.
Pulmonary blood flow:
Has a mean arterial pressure of 25-30 mmHg
False. Mean pressure is around 15 mmHg. 25 -30mmHg would be the systolic pressure.
Pulmonary blood flow:
In West zone 1, occurs mainly during diastole
False. In West zone 1 pA>pa>pv therefore the pulmonary capillary is completely compressed by by the alveolus ceasing. This results in a very high V/Q ratio
Pulmonary blood flow:
Of 6000 ml/min with a minute ventilation of 4000 ml/min suggests the presence of a shunt
True. As perfusion is significantly greater than ventilation.
Pulmonary blood flow:
Is maximal in zone 2
False. It is maximal in zone 3.
Restrictive lung disease is characterized by:
A fall in FEV1
True. Pulmonary function tests generally reveal a decrease in both FEV1 and FVC with a normal FEV1/FVC ratio.
Restrictive lung disease is characterized by:
A fall in arterial PO2
True. A fall in FRC causes alveolar collapse with a resultant shunt.
Restrictive lung disease is characterized by:
A fall in FEV1/FVC ratio
False.
Restrictive lung disease is characterized by:
Carbon dioxide retention
False.
Restrictive lung disease is characterized by:
A fall in vital capacity
True. As does TLC and FRC.
During intermittent positive pressure ventilation:
Mean intrathoracic pressure will be lower than during spontaneous breathing
False.
During intermittent positive pressure ventilation:
Right ventricular filling falls compared with spontaneous ventilation
True. Which will reduce cardiac output.
During intermittent positive pressure ventilation:
PEEP will reinflate collapsed alveoli
False. PEEP will prevent collapse, but would not normally be high enough to re-inflate collapsed lung.
During intermittent positive pressure ventilation:
Right ventricular workload may increase
True. PVR may rise during IPPV due to hyperinflation or alveolar collpase (PVR is lowest at FRC and rises above or below this).
During intermittent positive pressure ventilation:
Left ventricular workload may decrease
True. IPPV reduces LV afterload by decreasing LV cavity size and transluminal wall tension.
Hyperventilation produces:
Muscle spasm
True. Alkalosis decreases the proportion of ioised calcium, causing tetany.
Hyperventilation produces:
A raised pH
True.
Hyperventilation produces:
Decreased cerebral blood flow
True.
Hyperventilation produces:
Peripheral vasodilatation
False. Hypocarbia causes vasoconstriction by a direct effect.
Hyperventilation produces:
Increased cardiac output
False. Hypercarbia causes an increase in cardiac output due to increased sympathetic activity. The direct effect of vasoconstriction from hypocarbia will reduce cardiac output.
