Week 5 - Lung function

Question 1

What is Fick’s law of diffusion?

Answer 1

Question 2

What structures comprise the conducting zone of the airways?

Answer 2

trachea, bronchi, bronchioles and terminal bronchi

Question 3

At what generation of airway does the conducting zone end?

Answer 3

16

Question 4

Define the term compliance

Answer 4

change in volume over change in pressure

measure of elesticity and how easily something will return to its original state

Question 5

Define the term elastic recoil

Answer 5

ability of something to return to its resting volume

Question 6

What is the arrangement of connective tissues in the lung?

Answer 6

elastin and collagen fibres linked together in a mesh

Question 7

What is anatomical dead space?

Answer 7

The volume of the conducting airways

dead space is all the volume of the respiratory system where gaseous exchange does not occur

Question 8

What is alveolar dead space?

Answer 8

alveoli that are ventilated but not perfused

no gas exchange is occuring

negligable in healthy individuals but increases dramatically in some lung diseases because of a ventilation-perfusion mismatch

Question 9

Which area of the lung receives the most perfusion?

Answer 9

the base because of the effects of gravity

has a low V:Q ratio

Question 10

At does a V:Q ratio of zero suggest?

Answer 10

no ventilation

abnormal

Question 11

What is the function of the conducting zone?

Answer 11

warm and humidify inspired air

filtration and removal of foreign material

transfer of air to alveoli

Question 12

What is the definition of functional residual capacity (FRC)?

Answer 12

the volume of air present in the lungs at the end of passive expiration

volume of gas present when the respiratory muscles are completely relaxed

Question 13

Is the following statement true or false?

In the upright position the lung bases receive a greater proportion of ventilation than the apices

Answer 13

TRUE

due to the effects of gravity

Question 14

What is the effect of a local decrease in ventilation:perfusion ratio?

Answer 14

A low V:Q ration indicates high perfusion but low ventilation

To correct the ratio the body can vasoconstrict the arteries to decrease perfusion and increase ventilation by bronchodilation

Question 15

Why can COPD lead to right heart failure?

Answer 15

COPD patients have a chronically low V:Q ratio across the whole lung

Pulmonary vasoconstriction occurs to reduce perfusion and correct the ratio but this raises the blood pressure in the pulmonary artery and leads to cor pulmanale

Question 16

What is a right to left shunt?

Answer 16

blood passing through the lung without coming into contact with alveolar air

perfused alveoli which are not ventilated

Question 17

What is the normal V:Q?

Answer 17

0.8, although in some areas of mid-lung it may be 1

Question 18

What does a V:Q of infinity indicate?

Answer 18

anatomical dead space or ventilated alveoli that are not perfused

Question 19

Does the apex or base of the lung have a higher V:Q ratio?

Answer 19

apex - higher

base - lower

ventilation and perfusion increase when going from apex to base but perfusion increases more strongly, thus lowering the VQ ratio

Question 20

What is an area of perfusion but no ventilation called?

Answer 20

a shunt