Ventilation and Compliance 2

Question 1

What are the 2 kinds of cells that makes up alveolar walls?

Answer 1

Type 1 (gas exhange)

Type 2 (secretes surfactant fluid)

Question 2

What do type 1 cell of alveoli do?

Answer 2

Allows gas exchange

Question 3

What do type 2 cells of alveoli do?

Answer 3

Secretes surfactant fluid

Question 4

What is surfactant?

Answer 4

Detergent like fluid produced by type 2 alveolar cells

Question 5

What does surfactant do?

Answer 5

Reduces surface tension on alveolar surface membranes, reducing tendancy for alveoli to collapse

Question 6

What is surface tension?

Answer 6

Attraction between water molecules, occurs wherever there is an air-water interface

Question 7

What does surfactant do to the compliance of the lung?

Answer 7

Increases it

Question 8

What does surfactant do to the lungs tendency to recoil?

Answer 8

Reduces it

Question 9

Is surfactant more effective in small or large alveoli, and why?

Answer 9

Small because surfactant molecules come closer together and are therefore more concentrated

Question 10

Why does air spread evenly between small and large alveoli although there would be a pressure difference?

Answer 10

Surfactant reduces surface tension better in small alveoli, making the pressure in small and large equal

Question 11

When does surfactant production begin and is completed by?

Answer 11

About 25 weeks gestation and is completed by 36 weeks

Question 12

What is production of surfactant stimulated by?

Answer 12

Thyroid hormones which increase towards the end of pregnancy

Question 13

What do premature babies often suffer from due to surfactant production being complete at week 36?

Answer 13

Infant respiratory distress syndrome

Question 14

What is a saline filled lung similar to?

Answer 14

A lung in utero

Question 15

Why does a lung in utero require a smaller change in pressure to inflate?

Answer 15

Does not need to overcome surface tension (no air-water interface)

Question 16

What is compliance?

Answer 16

Change in volume relative to change in pressure

Question 17

What does compliance of the lung represent?

Answer 17

Stretch ability of the lung (not elasticity)

Question 18

What does a high compliance mean?

Answer 18

Large increase in lung volume for a small increase in ip pressure

Question 19

What does a low compliance mean?

Answer 19

Small increase in lung volume for a large decrease in ip pressure

Question 20

What does compliance change with?

Answer 20

Disease and age

Question 21

Does it require a greater change in pressure from fictional residual capacity to reach a lung volume during inspiration or expiration?

Answer 21

Greater change in pressure is required during inspiration

Question 22

Why is expiration passive?

Answer 22

Work on inspiration is recovered as elastic recoil during expiration

Question 23

What is emphysema?

Answer 23

Loss of elastic tissue means expiration requires effort (image c)

Question 24

What is loss of elastic tissue called?

Answer 24

Emphysema

Question 25

What is fibrosis?

Answer 25

Inert fibrous tissue means effort of inspiration increases (image d)

Question 26

What is inert fibrous tissue called?

Answer 26

Fibrosis

Question 27

What does inert mean?

Answer 27

Lacking the ability or strength to move

Question 28

Does emphysema make inspiration or expiration more difficult?

Answer 28

Expiration (image c)

Question 29

Does fibrosis make inspiration or expiration more difficult?

Answer 29

Inspiration (image d)

Question 30

What does the pressure/volume curve vary between?

Answer 30

The apex and the base of the lung

Question 31

Is the volume change (compared to change in pressure) greater at the base or the apex of the lung?

Answer 31

Base

Question 32

How does alveolar ventilation and compliance change with height from the base to the apex and why?

Answer 32

Decreases due to alveolar at the apex being more inflated at functional residual capacity

Question 33

Why are the alveoli at the base more compliant during inspiration?

Answer 33

They are compressed between the lung above and the diaphragm below

Question 34

How does the change in intrapleural pressure affect the change in volume at the base of the lung compared to the apex?

Answer 34

Brings about a larger change at the base compared to the apex

Question 35

What are the 2 categories of lung disease?

Answer 35

Obstructive Restrictive

Question 36

What does an obstructive lung disease mean?

Answer 36

Obstruction of airflow, especially on expiration

Question 37

What could an obstructive lung disease be due to?

Answer 37

Increased airway resistance

Question 38

What does a restrictive lung disease mean?

Answer 38

Restriction of lung expansion

Question 39

What could a restrictive lung disease be due to?

Answer 39

Loss of lung compliance, leading to lung stiffness and incomplete lung expansion

Question 40

What are examples of obstructive lung diseases?

Answer 40

Asthma Chronic obstructive pulmonary disease (COPD)

Question 41

What are examples of chronic obstructive pulmonary diseases?

Answer 41

Chronic bronchitis Emphysema

Question 42

What is chronic bronchitis?

Answer 42

Inflammation of the bronchi

Question 43

What is emphysema?

Answer 43

Destruction of alveoli, loss of elasticity

Question 44

What is destruction of the alveoli known as?

Answer 44

Emphysema

Question 45

How many people suffer from moderate to severe chronic obstructive pulmonary disease (COPD) worldwide?

Answer 45

80 million people

Question 46

What percent of the UK population suffers from chronic obstructive pulmonary disease (COPD) and how does this change with age?

Answer 46

About 1%, which increases with age

Question 47

What percent of men older than 75 suffer from chronic obstructive pulmonary disease (COPD)?

Answer 47

10%

Question 48

What are examples of restrictive lung diseases?

Answer 48

Fibrosis Infant respiratory distress syndrome Oedema Pneomothorax

Question 49

What is infant respiratory distress syndrome?

Answer 49

Insufficient surfactant production

Question 50

What is spirometry?

Answer 50

Technique used to measure lung function

Question 51

What can the measurements from spirometry be classed as?

Answer 51

Static (where the only consideration made is the volume exhaled) Dynamic (where the time taken to exhale a certain volume is what is being measured)

Question 52

What are static spirometry measurements?

Answer 52

Ones where the only consideration made is the volume exhaled

Question 53

What are dynamic spirometry measurements?

Answer 53

Ones where the time taken to exhale a certain volume is what is being measured

Question 54

What measurements can be made directly from spirometry?

Answer 54

Tidal volume Inspiratory reserve volume Expiratory reserve volume Inspiratory capacity Vital capacity

Question 55

What is FEV₁?

Answer 55

Forced expiratory volume in 1 second

Question 56

What is FEV₁ for a fit, healthy, young adult male?

Answer 56

4L

Question 57

What is FVC?

Answer 57

Forced vital capacity

Question 58

What is forced vital capacity for a fit, healthy young adult male?

Answer 58

5L

Question 59

What is the normal FEV₁/FVC ratio for healthy young men?

Answer 59

80%

Question 60

How does the FEV₁/FVC ratio change with obstructive and restrictive diseases?

Answer 60

Restrictive - FEV₁ and FVC decrease, ratio decreases Obstructive - FEV₁ and FVC decrease, ratio increases

Question 61

Why is FEV₁ reduced by a much greater extent than FVC for obstructive lung diseases?

Answer 61

Because major effect on airways

Question 62

Why is FVC decreased in restrictive lung diseases?

Answer 62

Due to limitations on lung expansion

Question 63

Why is the FEV₁/FVC ratio not always a good indicator of health?

Answer 63

Because disease can cause it to decrease or increase, as seen with obstructive and restrictive lung disease

Question 64

What is forced expiratory flow (FEF_25-75)?

Answer 64

Average expired flow over the middle of an FVC

Question 65

How do changes for forced expiratory flow compare to FEV₁ with disease?

Answer 65

They correlate but changed for forced expiratory flow are more striking