Lecture 3 (Test 2)

Question 1

What is expected in areas with the highest effect of gravity regarding blood flow?

Answer 1

The highest blood flow is expected in Zone 3.

Question 2

What is gravity dependence in relation to blood vessels in the lungs?

Answer 2

Gravity dependence refers to lower vascular resistance in areas of the lungs where blood vessels are more distended due to gravity.

Question 3

In healthy individuals, which zones of blood flow are typically present in the lungs?

Answer 3

Healthy individuals typically only have Zone 2 and Zone 3 blood flow.

Question 4

What characterizes blood flow towards the top and the base of the lung?

Answer 4

Pulsatile blood flow towards the top and continuous blood flow towards the base.

Question 5

What condition leads to the presence of Zone 1 in the lungs?

Answer 5

Zone 1 occurs in pathological conditions, such as being unhealthy or on a mechanical ventilator.

Question 6

Where is West Zone 4 located in the lung?

Answer 6

West Zone 4 is located at the very bottom of the lung, compressed by the weight of the lung.

Question 7

What is the alveolar pressure at the start of a respiratory cycle?

Answer 7

The alveolar pressure is zero.

Question 8

What is the starting pleural pressure in the lungs?

Answer 8

The starting pleural pressure is -5.

Question 9

What does the negative pleural pressure do in the lungs?

Answer 9

It serves to hold the alveolus open.

Question 10

What happens to pleural pressure during inspiration?

Answer 10

Pleural pressure lowers to -6.

Question 11

What is the relationship between pleural pressure and inward recoil pressure during inspiration?

Answer 11

Lower pleural pressure creates an imbalance that allows alveolar pressure to change.

Question 12

What is the formula relating alveolar pressure, pleural pressure, and elastic recoil pressure?

Answer 12

Alveolar pressure = pleural pressure + elastic recoil pressure.

Question 13

What is transpulmonary pressure?

Answer 13

Transpulmonary pressure is another name for elastic recoil pressure.

Question 14

How does transpulmonary pressure affect lung volume?

Answer 14

Increased transpulmonary pressure leads to increased lung volume.

Question 15

What are the two primary passive influences on pulmonary vascular resistance?

Answer 15

• Lung volume
• Gravity

Question 16

What happens to pulmonary vascular resistance when norepinephrine or epinephrine is introduced?

Answer 16

Pulmonary vascular resistance increases.

Question 17

What is the lowest possible lung volume in a healthy adult?

Answer 17

Residual volume (RV), approximately 1.5L.

Question 18

What is the highest lung volume achievable in a healthy adult?

Answer 18

Total lung capacity (TLC).

Question 19

What is functional residual capacity (FRC) in relation to RV and TLC?

Answer 19

FRC is skewed to the left of the midpoint between RV and TLC.

Question 20

What does FRC stand for in lung physiology?

Answer 20

Functional Residual Capacity

FRC is the volume of air remaining in the lungs after a normal expiration.

Question 21

How does inspiratory reserve volume (IRV) compare to expiratory reserve volume (ERV) in relation to FRC?

Answer 21

IRV is greater than ERV

This relationship causes FRC to be skewed towards the left on the volume axis.

Question 22

What is the relationship between FRC and pulmonary vascular resistance (PVR)?

Answer 22

PVR is at its lowest at FRC

This suggests that spending time at FRC is beneficial for heart function.

Question 23

What happens to pulmonary vascular resistance when lung volume increases from FRC?

Answer 23

Pulmonary vascular resistance increases

This trend also occurs when lung volume decreases from FRC.

Question 24

What are the two general components of total pulmonary vascular resistance?

Answer 24

• Extra alveolar blood vessels
• Alveolar blood vessels

Question 25

What is the effect of pleural pressure on extra-alveolar blood vessels?

Answer 25

Higher pleural pressure narrows the blood vessels, increasing vascular resistance ## Footnote Conversely, lower pleural pressure widens these vessels, decreasing resistance.

Question 26

What is the expected effect of increased lung volume on extra-alveolar vascular resistance?

Answer 26

Decreased extra-alveolar vascular resistance ## Footnote This occurs due to the negative pleural pressure pulling the blood vessel walls apart.

Question 27

What happens to alveolar vascular resistance as lung volume increases?

Answer 27

Alveolar vascular resistance increases ## Footnote This is due to the stretching of capillaries as the volume of air in the alveoli increases.

Question 28

What is the relationship between lung volume and the length of capillaries in the alveoli?

Answer 28

Increased lung volume leads to longer capillaries ## Footnote This results in higher pulmonary vascular resistance.

Question 29

What is the total pulmonary vascular resistance a function of?

Answer 29

The sum of alveolar and extra-alveolar vascular resistances

Question 30

How does positive pressure ventilation affect pulmonary vascular resistance?

Answer 30

It can increase vascular resistance in extra-alveolar blood vessels ## Footnote This is because positive pressure pushes against the walls of the blood vessels.

Question 31

What happens to the capillaries' diameter at low lung volumes?

Answer 31

Capillaries are shorter and wider ## Footnote This contributes to lower vascular resistance.

Question 32

What is the effect of higher right heart cardiac output on pulmonary vascular resistance?

Answer 32

It can decrease pulmonary vascular resistance ## Footnote This is due to the increased volume of blood in the vessels.

Question 33

At what lung volume is pulmonary vascular resistance typically the lowest?

Answer 33

At Functional Residual Capacity (FRC)

Question 34

True or False: The relationship between pleural pressure and vascular resistance is direct.

Answer 34

False ## Footnote Increased pleural pressure leads to increased vascular resistance.

Question 35

What happens to pulmonary vascular resistance when right heart cardiac output increases?

Answer 35

Pulmonary vascular resistance typically decreases ## Footnote This is because an increase in blood volume leads to distension of compliant blood vessels.

Question 36

Define distension in the context of the cardiovascular system.

Answer 36

Widening of blood vessels due to increased blood volume ## Footnote Distension lowers pulmonary vascular resistance.

Question 37

What is recruitment in relation to pulmonary blood flow?

Answer 37

The process of utilizing additional unused blood vessels for blood flow ## Footnote Recruitment lowers vascular resistance by increasing the number of pathways for blood.

Question 38

What is the relationship between cardiac output and pulmonary vascular resistance?

Answer 38

Higher cardiac output leads to lower pulmonary vascular resistance ## Footnote This relationship is counterintuitive compared to the systemic circuit.

Question 39

What effect does gravity have on pulmonary vascular resistance?

Answer 39

Dependent regions of the lung typically have lower vascular resistance than less dependent regions ## Footnote This is due to the influence of gravity on blood distribution in the lungs.

Question 40

How does blood viscosity affect pulmonary vascular resistance?

Answer 40

Increased blood viscosity leads to increased pulmonary vascular resistance ## Footnote Thicker blood makes it harder to flow through the circuit.

Question 41

What is the effect of positive pressure ventilation on pulmonary vascular resistance?

Answer 41

It typically increases pulmonary vascular resistance ## Footnote Positive pressure can compress blood vessels in the chest.

Question 42

Name two factors that increase pulmonary vascular resistance.

Answer 42

* Alpha agonists * Sympathetic stimulation ## Footnote Both factors tend to constrict pulmonary blood vessels.

Question 43

Which prostaglandin is known to relax pulmonary blood vessels?

Answer 43

Prostacyclin (PGI2) ## Footnote It has been studied as an inhalable treatment for pulmonary hypertension.

Question 44

What is the atmospheric pressure at sea level?

Answer 44

760 mmHg ## Footnote This is equivalent to 1 atm or 760 torr.

Question 45

What is the concentration of nitrogen in the atmosphere?

Answer 45

79% ## Footnote Nitrogen is the most abundant gas in the atmosphere.

Question 46

How do you calculate the partial pressure of a gas?

Answer 46

Multiply the atmospheric pressure by the concentration of the gas ## Footnote For example, PN2 = atmospheric pressure x 0.79.

Question 47

What happens to gas pressure at higher altitudes?

Answer 47

Atmospheric pressure decreases ## Footnote This results in lower partial pressures for the gases.

Question 48

What is the partial pressure of oxygen at sea level?

Answer 48

159 mmHg ## Footnote This is calculated from 21% of 760 mmHg.

Question 49

What effect does water vapor have on inspired gas pressures?

Answer 49

Water vapor displaces other gases, reducing their partial pressures ## Footnote At body temperature, the partial pressure of water vapor is 47 mmHg.

Question 50

What is the significance of the term 'torr'?

Answer 50

It is equivalent to mmHg ## Footnote Both are units of pressure measurement.

Question 51

What is the role of atmospheric pressure in gas exchange?

Answer 51

It drives the movement of gases into the body ## Footnote Gas movement requires both gas and pressure.

Question 52

What happens to pulmonary vascular resistance if right heart cardiac output drops?

Answer 52

Pulmonary vascular resistance increases ## Footnote This can create a vicious cycle of worsening heart function.

Question 53

What happens to atmospheric air as it hits the nose and upper airways?

Answer 53

It is warmed quickly and humidified rapidly.

Question 54

What effect does water vapor have on the partial pressures of other gases in inspired air?

Answer 54

It dilutes the other gases, reducing their partial pressures.

Question 55

What does PIO2 represent?

Answer 55

The partial pressure of oxygen in humidified gas.

Question 56

How much does the partial pressure of oxygen decrease in humidified air compared to dry atmospheric air?

Answer 56

About 10 mmHg.

Question 57

What is the dry atmospheric air PO2 value?

Answer 57

159 mmHg.

Question 58

What is the PO2 of humidified air after accounting for water vapor?

Answer 58

149 mmHg.

Question 59

What is the partial pressure of water vapor that remains constant in the lungs?

Answer 59

47 mmHg.

Question 60

What is the formula for calculating PIO2?

Answer 60

PIO2 = FIO2 (PB – PH20).

Question 61

Does altitude affect the partial pressure of water vapor?

Answer 61

No, it remains 47 mmHg regardless of altitude.

Question 62

What is the effect of bringing in fresh air on the PAO2?

Answer 62

It increases the PAO2.

Question 63

What happens to PACO2 when fresh air is introduced?

Answer 63

It decreases.

Question 64

What is the typical PO2 of pulmonary arterial blood?

Answer 64

About 40 mmHg.

Question 65

How does oxygen partial pressure change as blood moves through the pulmonary capillaries?

Answer 65

It increases from 40 mmHg to 100 mmHg.

Question 66

What is the typical PCO2 of pulmonary arterial blood?

Answer 66

About 45 mmHg.

Question 67

How is carbon dioxide unloaded from the blood into the alveoli?

Answer 67

Simultaneously with oxygen absorption.

Question 68

What are the average gas pressures in the alveoli of a normally functioning lung?

Answer 68

* PAO2: about 100 mmHg * PACO2: about 40 mmHg.

Question 69

What is the alveolar water vapor partial pressure?

Answer 69

47 mmHg.

Question 70

What is the effect of fresh air on the alveolar gas composition?

Answer 70

It increases PAO2 and decreases PACO2.

Question 71

What is the significance of the alveolar gas pressures?

Answer 71

They indicate the efficiency of gas exchange in the lungs.

Question 72

What is the term used to describe the pressure of oxygen in alveolar gas?

Answer 72

PAO2.

Question 73

What happens continuously in the lungs regarding gas exchange?

Answer 73

Oxygen is absorbed and CO2 is unloaded.

Question 74

What is the average alveolar PO2 expected in the lungs?

Answer 74

About 100 mmHg.

Question 75

What is the typical alveolar PACO2 after gas exchange?

Answer 75

About 40 mmHg.

Question 76

Fill in the blank: The partial pressure of water vapor in the lungs is always _______.

Answer 76

[47 mmHg]