Effects of Anaesthesia on Lung Function

Question 1

Regarding the humidification of inspired gas during normal resting nose breathing:

It is made more efficient by turbulent gas flow caused by the nasal turbinates

Answer 1

True. This results in better mixing of air and water vapour from airway lining fluid.

Question 2

Regarding the humidification of inspired gas during normal resting nose breathing:

It is not complete until inspired gas reaches the small bronchi

Answer 2

False. It is complete when gas reaches the trachea in quiet breathing.

Question 3

Regarding the humidification of inspired gas during normal resting nose breathing:

It occurs due to evaporation of water from the mucous layer of airway lining fluid

Answer 3

True. The mucous layer is the most superficial and contains abundant water for evaporation.

Question 4

Regarding the humidification of inspired gas during normal resting nose breathing:

It is facilitated by the viscoelastic properties of mucin

Answer 4

False. The viscoelastic nature of mucins has no effect on water evaporation.

Question 5

Regarding the humidification of inspired gas during normal resting nose breathing:

It influences the depth of the periciliary layer of airway lining fluid

Answer 5

False. The depth of the periciliary layer remains constant irrespective of the humidification role of the airway lining fluid.

Question 6

Which of the following substances are inactivated on passing through the pulmonary circulation?

A. Histamine
B. Lidocaine
C. Bradykinin
D. Adrenaline
E. Prostaglandin D2

Answer 6

A. Incorrect. Endothelial cells have no uptake system for histamine.

B. Correct. Any basic drug is inactivated.

C. Correct. This is rapidly metabolised by endothelial cell surface bound angiotensin converting enzyme.

D. Incorrect. Endothelial cells have no uptake system for adrenaline.

E. Correct. Active metabolism occurs on the cell surface.

Question 7

Regarding the cilia of the respiratory epithelial cells:

Cilia beat within the mucous layer of the airway lining fluid

Answer 7

False. Cilia can only beat in the low-viscosity periciliary layer.

Question 8

Regarding the cilia of the respiratory epithelial cells:

Cilial activity is impaired by inhaled anaesthetic agents

Answer 8

True. All inhaled anaesthetic agents slow cilial beat frequency.

Question 9

Regarding the cilia of the respiratory epithelial cells:

Cilia move the airway lining fluid along the airway at 10 mm/s

Answer 9

False. Cilia move at 4 mm/s.

Question 10

Regarding the cilia of the respiratory epithelial cells:

The recovery stroke of a single cilium beat occupies a majority of the total time

Answer 10

True. 75% of the time, the cilium is recovering from the effective stroke.

Question 11

Regarding the cilia of the respiratory epithelial cells:

Cilia tips only reach into the mucous layer during the effective stroke of each beat

Answer 11

True. This is how the cilium grips the mucus to move it along.

Question 12

Is the following compound present in airway lining fluid to facilitate defence against inhaled pathogens?

Immunoglobulin IgM

Answer 12

Incorrect. IgA is present in the upper airway and IgG is found in the lower respiratory tract.

Question 13

Is the following compound present in airway lining fluid to facilitate defence against inhaled pathogens?

Defensin peptides

Answer 13

Correct. Defensins are natural antibiotics present throughout the respiratory tract.

Question 14

Is the following compound present in airway lining fluid to facilitate defence against inhaled pathogens?

Surfactant protein A

Answer 14

Correct. Surfactant protein A in the alveoli has immunological activity.

Question 15

Is the following compound present in airway lining fluid to facilitate defence against inhaled pathogens?

Elastase

Answer 15

Correct. This is a protease enzyme present in mucous that is active against pathogens.

Question 16

Is the following compound present in airway lining fluid to facilitate defence against inhaled pathogens?

Angiotensin converting enzyme

Answer 16

Incorrect. This is only present in pulmonary circulation and has no immunological role.

Question 17

Does the following statement support the suggestion that the lung is an endocrine organ?

The lung converts angiotensin I into angiotensin II

Answer 17

False. Angiotensin is not produced in the lung.

Question 18

Does the following statement support the suggestion that the lung is an endocrine organ?

Pulmonary endothelium secretes nitric oxide which via its association with haemoglobin exerts an effect on systemic capillaries

Answer 18

True. A substance secreted into the blood by the lung exerts a physiological effect elsewhere in the body.

Question 19

Does the following statement support the suggestion that the lung is an endocrine organ?

Histamine secretion by the lung in response to inhaling an allergen causes bronchospasm

Answer 19

False. This is a local paracrine response.

Question 20

Does the following statement support the suggestion that the lung is an endocrine organ?

Pulmonary endothelium completely inactivates circulating adrenaline

Answer 20

False. Adrenaline is not produced by the lung.

Question 21

Does the following statement support the suggestion that the lung is an endocrine organ?

Fall in blood pressure secondary to secretion of prostaglandins following inhalation of an inhaled allergen

Answer 21

False. An endocrine effect is physiologically beneficial, while this one is a pathological response.

Question 22

Is the following statement concerning catecholamine metabolism by the pulmonary circulation correct?

It occurs by the action of monoamine oxidase in the endothelial cells

Answer 22

True. MAO is abundant in endothelial cells.

Question 23

Is the following statement concerning catecholamine metabolism by the pulmonary circulation correct?

It results in complete clearance of noradrenaline from the circulation

Answer 23

False. Only one-third is removed due to a lack of a specific uptake mechanism for noradrenaline.

Question 24

Is the following statement concerning catecholamine metabolism by the pulmonary circulation correct?

It is important for removing circulating histamine

Answer 24

False. Histamine is not taken up into endothelial cells.

Question 25

Is the following statement concerning catecholamine metabolism by the pulmonary circulation correct?

It results in complete clearance of 5-hydroxytryptamine from the circulation

Answer 25

True. A very specific uptake mechanism exists.

Question 26

Is the following statement concerning catecholamine metabolism by the pulmonary circulation correct?

It is dependent on highly specific uptake mechanisms on the endothelial cell surface

Answer 26

True. The metabolic enzymes are completely non-specific, so selective metabolism depends only on the molecular uptake systems.