Topic 3 - Respiratory System

Question 1

Relating to pulmonary circulation: The whole of the cardiac output passes through the lungs.

Answer 1

True

All the output of the right ventricle passes through the pulmonary circulation and the output of both right and left heart will be the same over any significant period.

Question 2

Relating to pulmonary circulation: The pressures in the pulmonary arteries are similar to those in the systemic arteries.

Answer 2

False

The systolic and diastolic pressures in the pulmonary arteries are about 25 and 8 mmHg respectively compared with 120/80 for the systemic arteries.

Question 3

Relating to pulmonary circulation: The mean pressure in the pulmonary arteries rises as cardiac output increases.

Answer 3

True

Although the pressure in the pulmonary arteries rises with increasing cardiac output, the increase is small as the resistance of the pulmonary circulation falls.

Question 4

Relating to pulmonary circulation: The resistance of the pulmonary circulation falls as the pulmonary blood flow increases.

Answer 4

True

Although the pressure in the pulmonary arteries rises with increasing cardiac output, the increase is small as the resistance of the pulmonary circulation falls.

Question 5

Relating to pulmonary circulation: In an upright man, pulmonary blood flow is greatest at the base of lung.

Answer 5

True

Question 6

Relating to pulmonary circulation: The pattern of pulmonary blood flow is dependent on posture.

Answer 6

True

Question 7

Relating to pulmonary circulation: The lungs inactivate all circulating vasoactive materials.

Answer 7

False

While the lungs inactivate many vasoactive materials such as bradykinin, they convert angiotensin I to its active form angiotensin II.

Question 8

The trachea, bronchi, and bronchioles are all prevented from collapsing by the cartilage in their walls.

Answer 8

False

The trachea and bronchi have cartilage rings or plates in their walls that allow them to stay open despite changes in intrapleural pressure. The bronchioles have no cartilage and may collapse when the intrapulmonary pressure exceeds the pressure in the airway.

Question 9

The upper airways play an important role in protecting the lungs from airborne particles.

Answer 9

True

Question 10

The small-diameter airways are the main sites of airways resistance.

Answer 10

False

The principal sites of airways resistance are the upper airways (mainly the nose and airway generations 1-6). The fll in resistance with the branching of the airways is the result of a very large increase in the total cross-sectional area.

Question 11

The alveoli are the only site of gas exchange.

Answer 11

False

While the alveoli are the principal site of gas exchange, the respiratory bronchioles and alveolar ducts also contribute to gas exchange.

Question 12

In a healthy lung, the distance between the alveolar air and the blood in the pulmonary capillaries is less than 1 μm.

Answer 12

True

Question 13

In a normal healthy individual with a total lung capacity of 6 litres: The tidal volume at rest is about 1 litre.

Answer 13

False

The tidal volume at rest would be about 500 ml.

Question 14

In a normal healthy individual with a total lung capacity of 6 litres: The vital capacity is equal to the total lung capacity.

Answer 14

False

The vital capacity is equal to the total lung volume minus the residual volume and the expiratory reserve volume is equal to the functional residual capacity minus the residual volume.

Question 15

In a normal healthy individual with a total lung capacity of 6 litres: The functional residual capacity is about 2 litres.

Answer 15

True

Question 16

In a normal healthy individual with a total lung capacity of 6 litres: The expiratory reserve volume at rest would be about 1 litre.

Answer 16

True

Question 17

In a normal healthy individual with a total lung capacity of 6 litres: The FEV1 would be about 3.5 litres.

Answer 17

True

Question 18

The change in the volume of the lungs with pressure is the compliance.

Answer 18

True

Question 19

The total compliance of the chest is determined solely by the compliance of the lungs.

Answer 19

False

The compliance of the chest is determined by that of the chest wall and the lungs.

Question 20

The recoil of the lungs assists inspiration.

Answer 20

False

Lung recoil assists expiration not inspiration.

Question 21

At the functional residual volume, the elastic recoil of the lungs is balanced by the elastic forces tending to expand the chest.

Answer 21

True

Question 22

The compliance of the lungs is determined by surface tension forces in the alveoli and by the elastic tissues of the lung parenchyma.

Answer 22

True

Question 23

Pulmonary surfactant maintains a constant surface tension in the alveoli.

Answer 23

False

Pulmonary surfactant reduces the work of breathing by lowering the surface tension of the air-liquid interface in the alveoli. The surface tension is related to the degree of inflation—the more the lungs are expanded, the higher is the surface tension.

Question 24

The anatomical dead space is the volume of air taken in during a breath, that does not enter the alveoli.

Answer 24

True

Question 25

The physiological dead space is always greater than the anatomical dead space.

Answer 25

True

Question 26

The anatomical dead space is independent of the tidal volume.

Answer 26

False

The physiological dead space is always greater than the anatomical dead space as it includes the volume of air taken up by alveoli that are not perfused by blood. These alveoli cannot take part in gas exchange. In healthy subjects, the difference is not great. When the lungs are expanded, the traction on the airways is increased and this dilates them. As a result, the dead space increases with tidal volume.

Question 27

In an upright lung, the alveolar ventilation is always highest at the base.

Answer 27

False

Alveolar ventilation is greatest at the base of the lungs for lung volumes at or above FRC. For lung volumes less than FRC, the ventilation at the apex may be greater than that at the base.

Question 28

The [V with dot above]A/[Q with dot above] ratio for a subject in a sitting position increases with distance above the base of the lung.

Answer 28

True

Question 29

The regional variation in [V with dot above]A/[Q with dot above] ratios is much smaller in subjects who are lying down.

Answer 29

False

Question 30

The diffusing capacity for carbon dioxide in the lungs is similar to that of oxygen.

Answer 30

False

While the volumes of carbon dioxide and oxygen exchanged during respiration are similar, the pressure gradient for carbon dioxide is much smaller. This is offset by the much greater diffusing capacity of carbon dioxide (about 20 times that for oxygen).

Question 31

The depth and rate of ventilation is increased when a subject breathes air containing 5 per cent carbon dioxide.

Answer 31

True

Question 32

The central chemoreceptors sense the carbon dioxide tension of the arterial blood.

Answer 32

True

Question 33

The peripheral chemoreceptors are located in the carotid sinus and aortic arch.

Answer 33

False

The receptors in the aortic arch and carotid sinus are baroreceptors that monitor the blood pressure.

Question 34

The peripheral chemoreceptors only respond to changes in the partial pressure of oxygen in the arterial blood.

Answer 34

False

The peripheral chemoreceptors are the carotid and aortic bodies, which sense plasma pH as well as the partial pressures of oxygen and carbon dioxide. They are the only chemoreceptors that respond to the partial pressure of oxygen in the arterial blood.

Question 35

False

The peripheral chemoreceptors are the carotid and aortic bodies, which sense plasma pH as well as the partial pressures of oxygen and carbon dioxide. They are the only chemoreceptors that respond to the partial pressure of oxygen in the arterial blood.

Answer 35

True

Question 36

Compliance tends to increase in the absence of surfactant.

Answer 36

False

Question 37

Compliance is influenced by the presence of elastin fibres.

Answer 37

True

Question 38

Compliance increases with ageing with adults.

Answer 38

False

Question 39

Compliance would be expected to be reduced in an individual suffering from emphysema.

Answer 39

False

Question 40

Compliance is unaffected by the surface tension forces.

Answer 40

False

Question 41

Which best describes Haldane Effect:

1) Promotes transport of O2 in systemic arterial blood
2) Shifts the CO3 disassociation curve to the right as blood pH falls
3) Promotes CO2 release in the pulmonary capillaries as the blood PO2 rises
4) Depends on increased CO2 binding by oxygenated Hb
5) The CO2 disassociation curve for systemic venous blood lies below that for systemic arterial blood

Answer 41

3) Promotes CO2 release in the pulmonary capillaries as the blood PO2 rises
The CO2 curve shift down and to the left as O2 increases

Question 42

Which is the best explanation of what happens when systemic PO2 is increased?

1) Increased PCO2 can cause respiratory acidosis
2) Increased PCO2 is a less potent stimulus for ventilation than decreased arterial PO2
3) Increased PCO2 decreases ventilation
4) Increased PCO2 tends to increase peripheral resistance
5) Increased PCO2 is likely in individuals living at altitude

Answer 42

1) Increased PCO2 can cause respiratory acidosis - caused by increased carbonic acid formation

Question 43

Expiratory Reserve Vol (ERV):

1) is the maximal vol of air that can be exhaled from the lungs after a normal expiration
2) is the vol of gas left in the respiratory system after exhaling maximally
3) is the vol breathed in each breath
4) is kept at a low vol so that the vast bulk of the alveolar gas can be replaced with fresh air during the next inspiration
5) is the vol breathed in each minute

Answer 43

1) is the maximal vol of air that can be exhaled from the lungs after a normal expiration

Question 44

During an airway obstruction, how would the respiratory function be altered?

1) A person with an obstructed airway is unable to inhale or exhale as fast
2) There would be increased resistance to flow
3) The total vol able to flow should be the same
4) A lower FEV1/FVC ratio
5) All of the above

Answer 44

5) All of the above

Question 45

The role of the peripheral chemoreceptors

1) are more strongly driven by H+ ion concentration and form the main respiratory centre drive in normal humans
2) are more sensitive to small changes in PO2 than PCO2
3) repsond by sending more nerve impulses to the respiratory centres, which stimulate the respiratory muscles, causing faster breathing
4) respond by sending more verve impulses to the respiratory centres, which stimulate the respiratory muscles, causing shallower breathing
5) increased carbon dioxide levels in the arterial blood result in increased blood pH, which stimulates the peripheral chemoreceptors

Answer 45

3) repsond by sending more nerve impulses to the respiratory centres, which stimulate the respiratory muscles, causing faster breathing

The peripheral chemoreceptors also respond to pH chances caused by PCO2 changes, however they directly monitor changes in the arterial blood, not the cerebrospinal fluid as the central chemoreceptors do.

Question 46

The most important factor controlling the rate and depth of breathing is

1) the effect of CO2 on the peripheral chemoreceptors
2) the effect of pH on the peripheral chemoreceptors
3) the effect of CO2 on the central chemoreceptors
4) the effect of O2 on the peripheral chemoreceptors
5) the effect of O2 on the central chemoreceptors

Answer 46

3) the effect of CO2 on the central chemoreceptors

Question 47

In the respiratory system, the major difference between a volume and a capacity is that

1) a volume is the sum of at least 2 capacities
2) a capacity is the sum of at least 2 volumes
3) their units are different
4) A and C are correct
5) B and C are correct

Answer 47

2) a capacity is the sum of at least 2 volumes

Question 48

Total Lung Capacity

1) Is the maximal vol of air that can be exhaled from the lungs after a normal expiration
2) Is the volume of gas left in the respiratory system after exhaling maximally
3) Is the vol breathed in each breath
4) Is the measure of maximum vol of gas in the respiratory system that can be exchanged with each breath
5) Is a measure of the vol of gas in the respiratory system at the end of a maximal inspiration

Answer 48

5) Is a measure of the vol of gas in the respiratory system at the end of a maximal inspiration

Question 49

The peripheral chemoreceptors are

A) found in the aortic bodies within the aortic arch

B) found in the carotid bodies at the bifurcation of the common carotid arteries

C) responsive to PCO2, pH, and PO2 in arterial blood

D) A and B are correct

E) A, B, and C are correct

Answer 49

A) found in the aortic bodies within the aortic arch

Question 50

What changes will occur if a person hyperventilates, i.e. breathes deeper and faster than necessary for normal gas exchange?

1) H+ ion conc will be high, the peripheral chemoreceptors will send fewer impulses to the respiratory centre, thus more nerve impulses will be sent to the respiratory muscles
2) Normally cause an increase in the O2 levels in the blood, because O2 is poorly soluble in blood and normally Hb in arterial blood is not fully saturated with O2
3) CO2 is exhaled, lowering PCO2
4) PCO2 will be low, the central chemoreceptors send more impulses to the respiratory centres
5) This increases H+ concentration and decreases pH

Answer 50

3) CO2 is exhaled, lowering PCO2

Question 51

In quiet breathing expiration

A) is largely passive, due to elastic recoil of the lung

B) is driven by the ANS

C) is a driven reflex initiated from lack of air movement in the airways

D) is activated by stimulation of the intercostal muscles in a reciprocal pattern to inspiration

E) is activated by stimulation of the diaphragm

Answer 51

A) is largely passive, due to elastic recoil of the lung