L05 - Pressure and compliance

Question 1

What is total lung capacity and the approx vol?

Answer 1

The volume of air in lungs after maximum effort of inspiration(approx 6L)

Question 2

What is the residual volume?

Answer 2

The volume of air left in lungs after forced expiration (approx 1.2L)

Question 3

What is the vital capacity?

Answer 3

The volume of air that can be expelled after taking the deepest possible inspiration (approx 4.8L)

Question 4

What is functional residual capacity?

Answer 4

The volume of air left in lungs after passive expiration (approx 2.7L)

Question 5

What is inspiratory capacity?

Answer 5

Volume of air that can be inspired following a quiet expiration (approx 3.3L)

Question 6

What is inspiratory reserve volume?

Answer 6

Additional volume of air that can be forcibly inhaled after inspiration of a normal tidal volume

Question 7

What is tidal volume?

Answer 7

Each breath we take (.5L)

Question 8

IRV + TV =

Answer 8

IC

Question 9

ERV + RV =

Answer 9

FRC

Question 10

What is expiratory reserve volume?

Answer 10

Additional volume of air that can be forcibly exhaled after inspiration of a normal tidal volume

Question 11

What factors can have an impact on lung volume?

Answer 11

• Height (taller>smaller)
• Sex (males > females)
• Age (lung volume inc with age, dec slightly with old age)
• Race (European > Asian)
• Respiratory disease

Question 12

What are the key indicators in a lung function test to identify a respiratory disease?

Answer 12

• Reduced flow rate

- Reduced volume

Question 13

What does Boyle’s law state?

Answer 13

• Describes the relationship between pressure and volumes of gases
• The pressure of a gas varies inversely with the volume of the gas at any given temp?
  i. e. if the vol is halved, the pressure is double

Question 14

What are the muscles of inspiration?

Answer 14

• External intercostal muscles

- Diaphragm

Question 15

What are the muscles of expiration?

Answer 15

• Internal intercostal muscles

- Abdominal muscles

Question 16

What are the accessory muscles of inspiration?

Answer 16

• Sternocleidomastoid
• Pecotralis major
• Pectoralis minor
• Serratus anterior
• Latissimus dorsi
• Serratus posterior
  superior
• Scalene muscles

Question 17

What are the accessory muscles of expiration

Answer 17

The abdominal muscles:

• Rectus
• Abdominis
• External oblique
• Internal oblique
• Transversus abdominis

Question 18

Function of resp muscles:

Answer 18

1. Stretch the elastic components of the respiratory system

2. To overcome the resistance to flow

Question 19

How will the air flow if PB = PA (barometric press = alveolar press)

Answer 19

No air will flow as there is no pressure difference

Question 20

What is the equation for Boyle’s Law

Answer 20

P1V1 = P2V2

Question 21

Describe what happens during inspiration with Boyle’s Law

Answer 21

Inc thoracic vol –> dec PA according to Boyle’s law (P1V1 = P2V2) –> diff in PB and PA created –> air moves into lungs until press equalises

Question 22

Describe what happens during expiration with Boyle’s law

Answer 22

Dec thoracic vol –> inc PA according to Boyle’s law (P1V1 = P2V2) –> diff in PB and PA created –> air moves out of lungs until press equalises

Question 23

What happens to the muscles during passive inspiration?

Answer 23

Diaphragm = contracts and flattens (pulls downwards)
= Ext sup and inf dimensions of thoracic cavity
EIM = Elevates the ribs and sternum
= Ext ant and post dimensions of thoracic cavity

Question 24

What happens to the muscles during passive expiration

Answer 24

Diaphragm = relaxes and returns to resting position (dome shaped)
= Red sup and inf dimensions of thoracic cavity
EIM = Relaxes to depress ribs and sternum
= Red ant and post dimension of thoracic cavity

Question 25

What happens to the accessory muscles during active inspiration?

Answer 25

``` Scalenes = Elevates upper ribs Sterno = Elevates sternum Pec major = Pulls ribs outwards Pec minor = Pulls ribs outwards Serr ant = Elevates ribs (when scapulae are fixed) Lat dorsi = Elevates lower ribs ```

Question 26

What happens to the accessory muscles during active expiration?

Answer 26

Anterolateral abdominal wall = Inc intra-abd press, pushes dia upwards into thoracc cavity Int inter = Depresses the ribs Innerm inter = Depresses the ribs

Question 27

What is the visceral pleura?

Answer 27

- Pleura that reflects from the medial wall and onto the surface of the lung - Adheres to and covers the lung

Question 28

What is the parietal pleura?

Answer 28

Pleura ass with the walls of a pleural cavity (covers the internal surface of the thoracic cavity)

Question 29

What is the pleural space?

Answer 29

- The potential space enclosed between the visceral pleura and parietal pleura - Filled with small amount of lubricating serous pleural fluid

Question 30

What is pleural effusion?

Answer 30

- Occurs when excess fluid acc within pleural space | - As fluid acc, underlying lung is compromised and may collapse as the vol of fluid inc

Question 31

What is a pneumothorax?

Answer 31

- Collection of gas or air within the pleural cavity - When air enters p. cav, the tissue elasticity of parenchyma causes lung to collapse within chest, impairing lung function

Question 32

What is a tension pneumothorax?

Answer 32

When so much air acc in the p. cavity that the mediastinum is pushed to the opp lung, compromising that lung as a result (req urgent treatment)

Question 33

What is the recoil tendency of the lungs?

Answer 33

Healthy lungs tend to recoil inwards away from the thoracic cage

Question 34

What is the recoil tendency of the thoracic cage?

Answer 34

The thoracic cage tends to recoil outwards away from the lungs

Question 35

What causes the sub-atmospheric pressure within the pleural space?

Answer 35

The inwards recoil of the lungs and the outwards recoil of the thoracic cage

Question 36

What is each pleural cavity lined by?

Answer 36

- Single layer of flat cells (mesothelium) - Ass later of supporting CT - Tgt they form the pleura

Question 37

Why does the parietal pleura and visceral pleura not ever actually touch each other?

Answer 37

Do not touch due to reciprocal repulsive forces of charges carried by polar phospholipids adsorbed on the opposing pleural surfaces

Question 38

What are pleural recesses?

Answer 38

When the lungs do not completely fill the ant/post inf regions of the pleural cavities

Question 39

What are the two possible recesses present in each pleural cavity?

Answer 39

1. Costodiaphragmatic recess | 2. Costomediastinal recess

Question 40

Why are pleural recesses important to know about?

Answer 40

They provide potential spaces in which fluids can collect and from which fluids can be aspirated

Question 41

What is the costodiaphragmatic recess and where does it occur? When is it deepest/ shallowest?

Answer 41

- Occurs in each pleural acvity between the costal pleura and diaphragmatic pleura - Deepest after forced exp - Shallowest after forced insp

Question 42

What is costomediastinal recess and where does it occur?

Answer 42

- Occurs on each side where costal pleura is opposed to mediastinal pleura (behind the sternum) - Largest on left side in the region overlying the heart

Question 43

How would you approximate the location of the costodiaphragmatic recess?

Answer 43

It is the region between the inferior margin of the pleural cavity and the inferior margin of the lung (would need to locate these margins)

Question 44

How would you locate the approx location of the inferior margin of the lung (during quiet resp)?

Answer 44

Inf margin crosses: - Rib 6 in the midclavicular line - Rib 8 in the midaxillary line - Courses roughly horizontally to reach the vertebral column at T10 - Therefore, the line running between rib6, rib 8 and vertebra T10

Question 45

How would you locate the approx location of the inferior margin of the pleural cavity?

Answer 45

The same points as the inf margin of lung but at rib 8, rib 10 and vertebra T12

Question 46

What happens to the inferior margin of the lung and costodiaphragmatic recess during expiration?

Answer 46

- Inf margin rises | - Costodiaphragmatic recess becomes larger

Question 47

During a normal breath, how many times does alveolar pressure cross 0kPa

Answer 47

3 times - Once at start of inspiration - Once at end of insp/ start of exp - Once at end of exp

Question 48

What happens to airflow when PA is 0

Answer 48

Airflow is also at 0 (it stops)

Question 49

Draw the graphs for Volume, airflow, recoil press alveolar press and intrapleural press

Answer 49

Look at L05 flipped for answer