Respiratory physiology 2

Question 1

What is the appoximate total volume of a lung?

Answer 1

6L

Question 2

What volume of air do the lungs normally contain at a normal respiration rate?

Answer 2

2.8L, however normally not all 2.8L are breathed out during expiration. typically 500ml

Question 3

Define ‘tidal volume’

Answer 3

The volume of air breathed in and out of the lungs at each breath

Question 4

Define ‘ Expiratory reserve volume’

Answer 4

The maximum volume of air which can be expelled from the lungs at the end of a normal respiration

Question 5

Define ‘Inspiratory reserve volume’

Answer 5

The maximum volume of airw which can be drawn into the lungs at the end of a nromal inspiration

Question 6

Define ‘Residual volume’

Answer 6

The volume of gas in the lungs at the end of a maximal expiration

Question 7

Define ‘vital capacity’

Answer 7

Total lung volume minus the residual volume. Essentially the total amount of air you can expire in one exhalation after fully filling up your lungs

Question 8

Define ‘functional residual capacity’

Answer 8

Volume of lungs at the end of a full relaxed exhalation

Question 9

Define ‘ inspiratory capacity’

Answer 9

tidal volume + inspiratory reserve volume

Question 10

How many pleural cavities are in the respiratory system

Answer 10

2 lungs = 2 pleural cavities

Question 11

Descibe what is meant by the ‘hilum of the lungs’

Answer 11

Point at which the lungs connect with the major airways

Question 12

Describe the parts of the pleural cavity

Answer 12

Visceral and parietal

Question 13

Describe the parietal aspect of the pleural fluid in the cavity

Answer 13

Part which is closes to the ribs and inferiorly stuck to the diaphragm

Question 14

Describe the visceral aspect of the pleural fluid in the cavity

Answer 14

Membrane attached to the organ of the lung (inner bit)

Question 15

What does the fluid in the plural sac allow for?

Answer 15

Friction free movement of the lung as parietal and visceral membranes remain in contact and glide across each other

Question 16

Define ‘ pleurisy’

Answer 16

Inflammation of the pleural membranes

Question 17

Define ‘pneumothorax’

Answer 17

When air is in the thoracic cavity, normally due to penetrating wounds to the chest

Question 18

How are the lungs stuck to the chest wall

Answer 18

Through the cohesive forces of the pleural membrane.
As the pleural fluid stops the lungs recoiling which results in a cohesive force against the elastic fibres which hold the lungs to the chest wall

Question 19

Why do alveoli not completely collapse and expire all air during expiration

Answer 19

Alveoli stay partially inflated to decrease energy loss

Question 20

State boyle’s law

Answer 20

The pressure exerted by a gas is inversely proportional to its volume.
e.g increased volume = decreased pressure.
decrease volume = increased pressure

Question 21

Gasses always move from ____ to ____ pressure

Answer 21

High to low pressure

Question 22

What are the muscles involved in expiration?

Answer 22

Internal intercostal muscles And abdominal muscles

Question 23

Describe the mechanism of the internal intercostal muscles within expiration

Answer 23

• Run in opposite direction to external intercostal muscles
• Pull the rib cage downwards and inwards
• Results in less volume = increases pressures and gas flows out

Question 24

Describe the mechanism of the abdominal muscles within expiration

Answer 24

• Push organs up against diaphragm which decreases volume of thoracic cavity
• Results in increased pressure in thoracic cavity which increases pressure

Question 25

Describe how the scalenes and the stemocleoidomastoids are used in increased respiratory load

Answer 25

They are used to expand the chest to allow more air into the thoracic cavity

Question 26

The diaphragm is responsible for what % of muscular activity during inspiration

Answer 26

70%

Question 27

What are intercostal muscles?

Answer 27

Muscles that run in between the ribs

Question 28

What type of intercostal muscle aids inspiration?

Answer 28

External intercostal muscles

Question 29

When are the Scalenes and stemocleoidmastoids used in respiration?

Answer 29

- During increased inspiratory load | - Used to expand the chest to allow more air into thoracic cavity

Question 30

Describe the internal intercostal muscles

Answer 30

- Run in opposite direction to external intercostal muscles | - Pull the ribcage downwards and inwards to air expiration

Question 31

Describe the abdominal muscles role in respiration?

Answer 31

- Push organs up against the diaphragm which decreases volume of thoracic cavity

Question 32

What are the muscles of expiration?

Answer 32

Internal intercostal muscles | Abdominal muscles

Question 33

What nerve innervated the diaphragm?

Answer 33

Phrenic nerve

Question 34

What happens when the diaphragm contracts?

Answer 34

- Increases the volume as the diaphragm becomes more straight - Pressure inside thoracic cavity becomes less than atmospheric pressure which causes inspiration

Question 35

What happens when the diaphragm relaxes?

Answer 35

- The volume of the thoracic cavity decreases - pressure increases - Expiration

Question 36

Describe the role of the external intercostal muscles within respiration?

Answer 36

- Raise the ribcage upwards and outwards - When they contract they lift up the sternum by lifting up the ribcage - Creates an increase in anterior posterior dimensions of thoracic cavity between sternum and sternum - Increases the lateral dimensions via the ribs - This aids inspiration as the increasing dimension helps decrease pressure

Question 37

Describe the role of the internal intercostal muscle within respiration

Answer 37

- Pull the ribcage down and decrease space - Diameter of airways increases during inspiration and decreases during expiration - (Opposite of external intercostal muscle)

Question 38

Define 'intra-thoracic alveolar pressure'

Answer 38

Pressure inside the thoracic cavity

Question 39

Explain what is meant by the intra thoracic alveolar pressure being: - Positive - Negative

Answer 39

``` Positive = greater than atmospheric pressure. Expiration Negative = less than atmospheric pressure. Inspiration ```

Question 40

Describe intra pleural pressure

Answer 40

- Usually negative | - Can become positive in some pathological situations

Question 41

What is meant by 'transpulmonary pressure'

Answer 41

The difference between the alveolar pressure and the intra pleural pressure

Question 42

the transpulmonary pressure is always what?

Answer 42

Positive as the intra pleural pressure is always negative

Question 43

Describe surfactant

Answer 43

- Detergent like fluid produced by type II alveolar cells

Question 44

What is the effect of surfactant?

Answer 44

Reduces surface tension on alveolar membrane thus reducing the tendency for alveoli to collapse

Question 45

What is meant by surface tension and when does it occur?

Answer 45

Whenever there is an air-water interface and refers to the attraction between the water molecules

Question 46

What is the effect of air needing to be fully saturated before it can diffuse from alveoli to the blood?

Answer 46

- Produces layer of fluid on surface level of alveoli and ir in the middle - air water interface THIS PRODUCES SURFACE TENSION BBBYYYYYYY

Question 47

Explain the mechanism of how surfactant prevents the collapse of alveoli

Answer 47

- Surface layer of water would create an inwardly directed pressure that would collapse alveoli as water is attracted to itself - Surfactant reduces attraction between water molecules - This reduces surface tension between water molecules. means alveoli don't collapse

Question 48

Does surfactant increase or decrease lung complaince?

Answer 48

Increases

Question 49

Does surfactant increase or decrease lung's tendancy to recoil?

Answer 49

Reduces

Question 50

Is surfactant more effective is small or large alveoli?

Answer 50

More effective in small alveoli than large alveoli because surfactant molecules come closer together and are therefore more concentrated

Question 51

At what stage of gestation does surfactant production start and end?

Answer 51

- starts ~25weeks gestation | - Complete ~36 weeks gestation

Question 52

What stimulates surfactant production?

Answer 52

Thyroid hormones and cortisol which increases towards the end of the pregnancy

Question 53

Describe infant respiratory distress syndrome

Answer 53

When premature babies do not have sufficient surfactant levels when born

Question 54

Define 'complaince'

Answer 54

Change in volume relative to change in pressure. - i.e how much does volume change for any given pressure. - This represents the stretchability of the lungs not the elasticity