3.1

Question 1

I. Lung volumes
1. What are the types of lung volumes?

Answer 1

Clinically, lung volumes are subdivided into dynamic and static lung volumes
1. Dynamic lung volumes: related to the rate at which air flows in/out of the lungs
2. Static lung volumes: not affected by the rate of airflow into/out of the lungs

Question 2

I. Lung volumes
2. Characteristics of Dynamic lung volumes

Answer 2

related to the rate at which air flows in/out of the lungs

Question 3

I. Lung volumes
3. Characteristics of Static lung volumes

Answer 3

not affected by the rate of airflow into/out of the lungs

Question 4

II. Static lung volume
1. What are 4 parameters of standard lung volumes?

Answer 4

1) Tidal Volume (TV)
2) Inspiratory reserve volume (IRV)
3) Expiratory reserve lung volume (ERV)
4) Residual volume (RV)

Question 5

II. Static lung volume
2. What is the definition and value of tidal volume (TV)

Answer 5

amount of air entering/ leaving the lung w/o extra effort (500mL)

Question 6

II. Static lung volume
3. What is the definition and value of Inspiratory reserve volume (IRV)?

Answer 6

max. inspiration above tidal volume (3100mL)

Question 7

II. Static lung volume
4. What is the definition and value of Expiratory reserve lung volume (ERV)

Answer 7

volume exhaled besides tidal volume(1200mL)

(The extra volume of air that can be expired with maximum effort beyond the level reached at the end of a normal, quiet expiration.)

Question 8

II. Static lung volume
5. What is the definition and value of Residual volume (RV)?

Answer 8

air remaining in the lungs after complete exhalation(1200mL)

Question 9

II. Static lung volume
6. What are the 4 standard capacities?

Answer 9

1. Inspiratory capacities (IC)
2. Functional residual capacity (FRC)
3. Vital capacity (TLC)
4. Total lung capacity

Question 10

II. Static lung volume
7. What are the definition and value for Inspiratory capacities (IC)?

Answer 10

IRV + TV, largest amount that can be inhaled
= 3600 mL

Question 11

II. Static lung volume
8. What are the definition and value for Functional residual capacity (FRC)?

Answer 11

ERV + RV, vol remaining in lungs after normal expiration (2400 mL)

Question 12

II. Static lung volume
9. What are the definition and value for Vital Capacity (VC)?

Answer 12

Entire volume that can be max. inhaled + exhaled
= 4800 mL

Question 13

II. Static lung volume
9. What are the definition and value for Total Lung Capacity (TLC)

Answer 13

The sum of all 4 volumes
= 6000 mL

Question 14

III. How does respiration take place?

Answer 14

Respiration takes place by movement of the respiratory muscles
=> If all muscles are relaxed, the volume in the lung is = the FRC (2400mL in male, 1800mL in females)

Question 15

III. Determination of FRC
1. What are the 2 method for the determination of FRC?

Answer 15

1. He dilution method
2. Body plethysmograph

Question 16

III. Determination of FRC
2. Describe He dilution method

Answer 16

• A closed-circuit system where a spirometer is filled with helium and oxygen
• Patient is asked to breath normally -> helium spreads into the lungs -> since no leak of substance, FRC is calculated by: C1 x V1 = C2 x (V1 + V2)
• V2 is unknown = FRC - volume at the end of normal expiration

Question 17

III. Determination of FRC
3. Describe Body plethysmograph

Answer 17

• Air-tight cabin
• Shutter which closes inhalation/exhalation
  +) Patient in the cabin can perform normal expiration. At the end of normal expiration, we close the shutter and ask the patient to make a forceful inhalation
  +) Patient cannot inhale because the shutter is closed. But can extend the chest and from that we can detect the pressure changes
  +) From the pressure changes, we can calculate what volume was inside the thorax, FRC, lung volume etc.

Question 18

IV. Dead spaces
1. What are the characteristics of dead spaces?

Answer 18

Dead spaces in the lungs relate to the part that do not participate in gas exchange

• dead space is the volume in the conductive zones (1-16)
• alveolar space is the volume in the respiratory bronchioles, alveolar ducts and sacs
  => ventilation occurs there

Question 19

IV. Dead space
2. What are the 2 methods for Determination of dead space?

Answer 19

1. O2-inhalation, N2-detection in expired gas
2. pCO2-measurement

Question 20

IV. Dead space
2A. How to determine dead space with O2-inhalation, N2-detection in expired gas?

Answer 20

• Ask patient to inhale O2 and to exhale it
• During exhalation period, we detect the N2 concentration
• As long as the person is exhaling from the dead space, there will be no N2, since the patient is just exhaling what was inhaled (pure O2)
  -> If we get the volume of where N2 appears, we can tell how much the dead space is

Question 21

IV. Dead space
2B. How to determine dead space by using pCO2-measurement?

Answer 21

in dead space, the pO2 and pCO2 concentration is equal to the outside pO2 and pCO2 concentration

Question 22

IV. Dead space
3. What is the anatomical dead space?

Answer 22

Anatomical dead space: is the volume of the conducting airway including the nose, mouth, trachea, bronchi and bronchioles.
-> When we take in a tidal volume of 500mL, 150mL of that air does not reach the alveoli for gas exchange

Question 23

IV. Dead space
4. What is Functional/physiological dead space?

Answer 23

It is the total volume of air that does not participate in gas exchange, thus, it is the anatomical dead space + the functional dead space of the alveoli
- Functional dead space is the space of the ventilated alveoli that do not participate in gas exchange
- Physiological dead space can occur if circulation/blood flow is blocked (thrombus)

Question 24

IV. Dead space
4A. How can physiological dead space occur?

Answer 24

Physiological dead space can occur if circulation/blood flow is blocked (thrombus):
- From this point (thrombus), there will be no gas exchange, but the alveolus is still ventilating
- The pO2 will be the same, as in the other alveolus (pO2=150)
- If no blood flow -> nowhere for the gases to go to -> the volume of the alveolus becomes part of the dead space, because there is no circulation

Question 25

V. Alveolar ventilation 1. What are the characteristics of Alveolar ventilation?

Answer 25

- There an inverse relationship (hyperbolic) between the alveolar ventilation (VA) and the alveolar pCO2 (PACO2) - Relationship between the CO2-production (VCO2) and PACO2 is a linear relationship => The equation tells us the relationship between work and breathing

Question 26

V. Alveolar ventilation 2. Give the formula for alveolar ventilation

Answer 26

Question 27

V. Alveolar ventilation 3. What happen if there is more work?

Answer 27

we produce CO2

Question 28

V. Alveolar ventilation 4. What happen if CO2-production (VCO2) increases during exercise?

Answer 28

If CO2-production (VCO2) increases during exercise, there will also be an increase in VA

Question 29

V. Alveolar ventilation 5. What happen if we have twice as much VCO2?

Answer 29

If we have twice as much VCO2, our body will regulate to us having twice as much VA, and keep PACO2 constant (40mmHg) -> Hypo/hyperventilation is based on pCO2-level in the alveoli (PACO2 is always 40mmHg, even during exercise) - Hypoventilation: PACO2 > 40mmHg (hypercapnia) - Hyperventilation: PACO2 < 40mmHg (hypocapnia)

Question 30

V. Alveolar ventilation 6. What is the value of PACO2 when there is hypoventilation?

Answer 30

Hypoventilation: PACO2 > 40mmHg (hypercapnia)

Question 31

V. Alveolar ventilation 7. What is the value of PACO2 when there is Hyperventilation?

Answer 31

Hyperventilation: PACO2 < 40mmHg (hypocapnia)

Question 32

VI. MECHANICAL PROPERTIES OF AIRWAYS, CHEST AND LUNG - Retraction tendency 1A. What are the characteristics of Retraction tendency?

Answer 32

- The lung (covered with visceral pleura) is attached to the chest wall (covered with parietal pleura) with the pleural fluid between them - During breathing, we do not move the lung, but the chest -> lungs move with the chest -> If we extend the chest, the lungs enlarge as well

Question 33

VI. MECHANICAL PROPERTIES OF AIRWAYS, CHEST AND LUNG 1B. What are the 2 reasons for the retraction tendency?

Answer 33

1. Elastic fibers 2. Surface tension

Question 34

VI. MECHANICAL PROPERTIES OF AIRWAYS, CHEST AND LUNG 1B. Why are elastic fibers a reason for the retraction tendency?

Answer 34

- Acts like a spring, extending the alveoli - Stretches when stress is applied -> allows for an increase in lung volume - Recoil passively when this stress is released -> spontaneously shrink back to the original size

Question 35

VI. MECHANICAL PROPERTIES OF AIRWAYS, CHEST AND LUNG 1C. Why is surface tension a reason for the retraction tendency?

Answer 35

- The walls of the alveoli are covered by a fluid layer which is wet - This fluid layer has a H2O-gas surface -> surface tension occurs => Surface tension reduces the surface -> reduces the alveoli and contributes to the retraction tendency

Question 36

VI. MECHANICAL PROPERTIES OF AIRWAYS, CHEST AND LUNG 1C1. How does surface tension occur?

Answer 36

Surface tension occurs due to the cohesion force of the H2O-molecules: 1. If we have a H2O-molecule inside the water, it has cohesion force with all surrounding molecules and the tension will be same in all direction = net effect is 0 (no surface tension) 2. A H2O-molecule at the surface will have cohesion force with all the other H2O-molecules, but not with the air on the other side -> cohesion force occurs only in 1 direction -> this direction is to pull the H2O-molecules together = net effect is that the surface tension tries to reduce the surface

Question 37

VI. MECHANICAL PROPERTIES OF AIRWAYS, CHEST AND LUNG 1C2. How does surface tension try to make the alveolus smaller?

Answer 37

Surface tension gives the (cohesion)force, which tries to make the alveolus smaller

Question 38

VI. MECHANICAL PROPERTIES OF AIRWAYS, CHEST AND LUNG 1C3. how do we keep the alveoli open?

Answer 38

- In order to keep the alveoli open, we need to counteract the ‘’retraction tendency’’ with another force. It can be 2 kinds of forces: 1. Positive force from the inside of the alveoli 2. Negative force from the outside of the alveoli => What keeps the alveoli open in a normal respiratory system, is the negative force from the outside, because the pressure around the alveoli is negative

Question 39

VI. MECHANICAL PROPERTIES OF AIRWAYS, CHEST AND LUNG 1D. Why is the pressure negative?

Answer 39

- The retraction tendency of the lung moves the chest inside by pulling it inwards - The chest will have an opposite (distension) tendency, which tries to counteract the retraction tendency of the lung by expanding

Question 40

VI. MECHANICAL PROPERTIES OF AIRWAYS, CHEST AND LUNG 1D1. What happen to the lung In normal resting conditions?

Answer 40

1. The lung is pulling inward 2. The chest (wall) is pulling outward => The intrapleural pressure will be negative => Will provide the negative pressure/force around the alveoli, which counteracts the retraction tendency and keeps the alveoli open

Question 41

VI. MECHANICAL PROPERTIES OF AIRWAYS, CHEST AND LUNG 2. What are the characteristic of Pneumothorax?

Answer 41

- If there is a puncture in the lung, air will enter the chest and will go to the intrapleural space -> lung compresses and collapses - The reason for that, is that the fluid layer between the lung and chest wall is very wet -> the lung and chest move together due to this wet layer, and when air enters the intrapleural space, this common movement will not be possible any more - Alveoli are the ones which have the retraction tendency -> makes the lung collapse, when we have a puncture (REMEMBER: lung compresses + chest expands)

Question 42

V. Pressures in the respiratory system 1. What are the characteristics of pleural space?

Answer 42

Between the lungs and chest wall exists a pleural space -> 2 pleural layers are separated by fluid = a potential (virtual) space, with a negative pressure within

Question 43

V. Pressures in the respiratory system 2. What are the 3 types of pressures you can find?

Answer 43

1. Pressure inside the lung 2. Pressure inside the pleural space 3. Pressure outside the lung + chest

Question 44

V. Pressures in the respiratory system 3. What are the characteristics of Pressure inside the lung?

Answer 44

Pressure inside the lung: alveolar (PA) or intrapulmonary (Ppulm) pressure

Question 45

V. Pressures in the respiratory system 4. What are the characteristics of Pressure inside the pleural space?

Answer 45

Pressure inside the pleural space: intrapleural (Ppl), intrathoracic (PTH) or esophageal (Pesophageal) pressure

Question 46

V. Pressures in the respiratory system 5. What are the characteristics of Pressure outside the lung + chest?

Answer 46

- Pressure outside the lung + chest: barometric (outer) pressure (PB)

Question 47

V. Pressures in the respiratory system 6. What happen to pressures in in the respiratory system When we are not breathing?

Answer 47

When we are not breathing (between inhalation and exhalation), air is not moving, therefore: - PB =PA -> PB =0,PA =0

Question 48

V. Pressures in the respiratory system 7. What keeps the alveoli and lung open?

Answer 48

What keeps the alveoli and lung open, is the negative pressure of the pleural pressure: - Ppl = -4 cmH2O (1 cmH2O = 0,7 mmHg) - This negative pressure is created by the retraction tendency of the lung (explained!)

Question 49

V. Pressures in the respiratory system 8. What does it mean when the lung has retraction tendency?

Answer 49

- Pulls the pleural sheet inwards - Pleural sheet pulls the thorax inwards

Question 50

V. Pressures in the respiratory system 9A. What is Transmural pressure (PTM)?

Answer 50

Transmural pressure (Ptm) is the pressure difference between the alveolar pressure and pleural pressure: - Ptm pressure inside (PA) – pressure outside (Ppl) - PTM = 0– (-4cmH2O) - PTM = + 4 cmH2O -> pressure which keeps alveoli open

Question 51

V. Pressures in the respiratory system 9B. What are the important parameters of pressures in the respiratory system?

Answer 51

Question 52

VI. Compliance of the lung 1. How is compliance of the lung measured?

Answer 52

Measured as how volume changes as a result of pressure change

Question 53

VI. Compliance of the lung 2. What happen if there is 1 cmH2O change in distending the pressure (how easily tissues stretch)?

Answer 53

Change in the volume due to a 1 cmH2O change in distending the pressure (how easily tissues stretch)

Question 54

VI. Compliance of the lung 3. What happen when the compliance of the lung is high or low?

Answer 54

- When compliance of the lung is high, the lung distends easily - When compliance is low, the lung is not easily distended => More elastic / flexible = more compliant

Question 55

VI. Compliance of the lung 4. Describe the Pressure-volume loop?

Answer 55

Compliance observed in the lung when filled with a liquid and a gas => Compliance = slope of the graph => Use slope at the level of FRC (functional residual capacity = resting state of respiratory system)

Question 56

VI. Compliance of the lung 5. Is lung more compliant with fluid or gas?

Answer 56

Fluid

Question 57

VI. Compliance of the lung 5A. Why is lung more compliant with fluid?

Answer 57

Lungs are more compliant with the fluid, something reduces the retraction force: 1. No surface tension, since all the nearby structures consist of fluid as well 2. No hysteresis (difference in inflation and deflation curves)

Question 58

VI. Compliance of the lung 5B. Why is lung less compliant with gas?

Answer 58

The gas has lower compliance. Also, we have hysteresis here (explained later!)

Question 59

VI. Compliance of the lung 6. What is the value of lung compliance?

Answer 59

C Lung = 0,2L/cmH2O (200mL/cmH2O)

Question 60

VI. Compliance of the lung 7A. How can we measure compliance of the lung?

Answer 60

plethysmography

Question 61

VI. Compliance of the lung 7B. How do we use plethysmography?

Answer 61

- Determine the FRC, and therefore the volume of the lung - Determine the pressure by measuring the PTM (= PA-Ppl) - PA measured by the tube in the plethysmograph, while Ppl is measured indirectly: Measure the Pesophageal instead, since Ppl = Pesophageal => Have all the values -> can construct a pressure-volume curve to measure the compliance

Question 62

VI. Compliance of the lung 8. How is compliance affected during pathological conditions?

Answer 62

The elasticity of the lung tissue is what affects the lung’s ability to inflate

Question 63

VI. Compliance of the lung 8B. Characteristics of fibrosis

Answer 63

- A patient with fibrosis has less elastic fibers and therefore difficulty to expand the lungs -> compliance ↓ (have to work harder to inflate) - Breathing will be more difficult for these patients

Question 64

VI. Compliance of the lung 8C. Characteristics of Emphysema:

Answer 64

- A patient with emphysema will have ↑ compliance, because the walls of the lungs are more flexible -> easy to expand the lungs = NOT GOOD! - Even in the resting state, the lung is already expanded - There is little room to expand it if more breathing is needed (e.g. when exercising) - Exhaling will require more effort - Overall surface for gas exchange is small -> dynamic problems

Question 65

VI. Compliance of the lung - Compliances of the chest and respiratory system 9. How is the compliance of the chest found?

Answer 65

- The compliance of the chest is found by the transmural pressure – difference between the inside pressure (pleural pressure) and the outside pressure (barometric pressure) - PTM = Ppl - PB -> compliance of the chest (Cchest = 0,2 L/cmH2O)

Question 66

VI. Compliance of the lung - Compliances of the chest and respiratory system 10. How is the compliance of the compliance of the whole respiratory system (lung + chest) found?

Answer 66

The compliance of the whole respiratory system (lung + chest) is also found by the transmural pressure – the difference between the inside pressure (alveolar pressure) and the outside pressure (barometric pressure) - PTM = PA - PB => compliance of the respiratory system (Cresp.system = 0,1L/cmH2O) => Since the slope of the whole system is less steep than those of the lung and the chest, the compliance will also be lower than the compliances of the chest and lung =>

Question 67

VI. Compliance of the lung - Compliances of the chest and respiratory system 11. What limits the inhalation?

Answer 67

- If we increase the volume, the chest curve will be linear => Not limited there, because it can be further expanded - If we look at the curve of the lung, it becomes flat at high volume levels => Compliance of the lung limits inhalation

Question 68

VI. Compliance of the lung - Compliances of the chest and respiratory system 11. What limits the inhalation?

Answer 68

- If we increase the volume, the chest curve will be linear => Not limited there, because it can be further expanded - If we look at the curve of the lung, it becomes flat at high volume levels => Compliance of the lung limits inhalation

Question 69

VI. Compliance of the lung - Compliances of the chest and respiratory system 12. What limits the exhalation?

Answer 69

- If we look at the lung curve at the minimal volume (RV), it is pretty linear -> Could be further decreased - The chest curve, on the other hand, becomes flat around (RV) -> Compliance of the chest limits exhalation

Question 70

VII. Surfactant 1. What are the characteristics of Surfactant?

Answer 70

- A surface-active material, composed of proteins and lipids - Found on the surface of alveoli - Reduces the surface tension - Has many different functions on the alveoli - It is synthesized from type II alveolar cells.

Question 71

VII. Surfactant 2A. How can surfactant help to reduce the work of breathing?

Answer 71

Work is the product of pressure and volume change, 𝑊 = 𝑝 ∗ ∆𝑉 - If there is a large refraction tendency, there will be a large pressure gradient present to keep the alveoli open (p↑) => Work is much larger if there is a large pressure gradient (refraction tendency) - With surfactant: small refraction tendency due to reduced surface tension (W↓) -

Question 72

VII. Surfactant 2B. What happen to the lung if there are 2 cases which are (1) with surfactants and (2) without surfactant?

Answer 72

- The surface tension will be reduced because the surfactant disrupts the cohesion forces between the H2O-molecules => Without surfactant: large refraction tendency (W↑) => With surfactant: small refraction tendency due to reduced surface tension (W↓)

Question 73

VII. Surfactant 2C1 . What happen to the lung of babies have pre-mature birth?

Answer 73

- Babies born before or around 6 months have low levels of surfactant (surfactant is produced in the last stages of pregnancy) => The baby will get exhausted by the large work of breathing (lack of surfactant)

Question 74

VII. Surfactant 2C2 . How do we treat babies with pre-mature birth?

Answer 74

1. Give glucocorticoids to the mother before birth => surfactant production↑ 2. Assisted breathing to the baby (- Babies born before or around 6 months have low levels of surfactant (surfactant is produced in the last stages of pregnancy) => The baby will get exhausted by the large work of breathing (lack of surfactant))

Question 75

VII. Surfactant 3. How does surfactant protect small alveoli from collapse?

Answer 75

- Surfactant reduces the surface tension (T↓) - We can see that the pressure is inversely proportional to the radius, which means that the small alveoli (with a small radius) will have a higher pressure than the large alveoli (with a larger radius) - The reduction of surface tension will be different in the 2 alveoli: -> In the small alveolus, the surface is small (large in large alveolus), and if we have the same amount of surfactant in both alveoli; the concentration of the surfactant will be more concentrated in the small alveolus and more diluted in the large alveolus

Question 76

VII. Surfactant 4A. What is edema?

Answer 76

Edema = swelling caused by excess fluid trapped in body tissues - Alveoli has a retraction tendency -> they want to become smaller => That retraction tendency provides a suction force for the capillary => The suction force causes the movement of fluid from the capillary to the interstitial space in the lung = pulmonary edema (Problem!)

Question 77

VII. Surfactant 4B. How can surfactant protect lung from edema?

Answer 77

- The presence of the surfactants will decrease the retraction tendency (suction force) which moves fluid out from the capillary and into the interstitial space => Less fluid is transported = no edema

Question 78

VII. Surfactant 5A. What is hysteresis?

Answer 78

Hysteresis = difference in the curves of deflation and inflation (if we start from a fully collapsed state) - Slope of deflation curve is more steep = large compliance - Slope of inflation curve is less steep = smaller compliance

Question 79

VII. Surfactant 5B. How is surfactant responsible for hysteresis?

Answer 79

1. If we let the lung collapse fully, the surfactant (surface- active material) will move out and into micelles, due to the small surface 2. If we then start to expand the lung, which has less surfactant, it will take more time/work, since the surface tension-reducing effect is decreased => Difficult to expand the lung (inhalation) 3. If the lung is fully expanded, the surfactants move back to the surface which makes the lung more compliant => Surface tension-reducing effect is increased => easier to deflate (exhalation)