Respiratory Cycle and Lung Volumes

Question 1

______ ______ = volume inspired or expired with each normal breath

Answer 1

Tidal volume

Question 2

How do you calculate minute ventilation rate?

Answer 2

Tidal volume x breaths/min

Question 3

How do you calculate minute alveolar ventilation rate?

Answer 3

(Tidal volume - dead space) x breaths/min

Question 4

Describe the relationship of air flow to the pressure difference between the mouth and the alveoli

Answer 4

Air flow is driven by and is directly proportional to the pressure difference between the mouth and the alveoli

Question 5

What is the relationship of alveolar pressure and atmospheric pressure at rest?

Answer 5

Alveolar pressure = atmospheric pressure

[because the lung pressures are expressed relative to atmospheric pressure, the alveolar pressure is said to be 0]

Question 6

What is the relative value of intrapleural pressure at rest?

Answer 6

Negative

[opposing forces of the lungs trying to collapse and the chest wall trying to expand creates a negative pressure in the intrapleural space between them]

Question 7

A balloon catheter placed in the esophagus would measure what type of pressure?

Answer 7

Intrapleural pressure

Question 8

What lung capacity value represents lung volume at rest (prior to inspiration)?

Answer 8

Functional residual capacity

Question 9

During inspiration, inspiratory muscles contract and cause the volume of the thorax to increase. As the lung volume increases, what happens to alveolar pressure? What is the result?

Answer 9

Decreases to less than atmospheric pressure (becomes negative)

Pressure gradient between atm and alveoli now causes air to flow into the lungs; air flow will continue until the pressure gradient dissipates

Question 10

What changes occur to intrapleural pressure during inspiration?

Answer 10

Becomes more negative because the elastic recoil strength of the lungs increases as lung volume increases

Question 11

Changes in intrapleural pressure during inspiration are used to measure the dynamic _______ of the lungs

Answer 11

Compliance

Question 12

How is lung volume calculated at the peak of inspiration?

Answer 12

Functional reserve capacity + one tidal volume

Question 13

What changes occur with alveolar pressure during expiration? What does this lead to?

Answer 13

Alveolar pressure becomes greater than atm (becomes positive) because alveolar gas is compressed by the elastic forces of the lung

Since alveolar pressure is now higher than atmospheric pressure, the pressure gradient is reversed and air will flow out of the lungs

Question 14

What changes occur with intrapleural pressure during normal, passive expiration?

Answer 14

Intrapleural pressure returns to its resting value during a normal passive expiration

Question 15

What occurs with intrapleural pressure during forced expiration?

Answer 15

Intrapleural pressure becomes more positive, which compresses the airways and makes expiration more difficult [this occurs in COPD patients]

Question 16

How might a COPD patient compensate for the collapse of the airways that occurs with forced expiration?

Answer 16

They exhale slowly with pursed lips

Question 17

What is the most important muscle of inspiration? How does it work?

Answer 17

Diaphragm

When the diaphragm contracts, the abdominal contents are pushed down and the ribs are lifted upward and outward, increasing the volume of the thoracic cavity

Question 18

What muscles of inspiration are not used during normal, quiet breathing? When are they used?

Answer 18

External intercostals
Accessory muscles

Used during exercise and in diseases causing respiratory distress

Question 19

Expiration is normally a passive process, so expiratory muscles are only used during exercise or when airway resistance is increased due to things like asthma.

What are considered the expiratory muscles?

Answer 19

Abdominal muscles

Internal intercostal mm.

Question 20

Abdominal muscles may be used in forced expiration, what is their action?

Answer 20

Compress the abdominal cavity, push the diaphragm up, and push air out of the lungs

Question 21

Internal intercostals may be used in forced expiration, what is their action?

Answer 21

Pull the ribs down and in

Question 22

Using a capital A, such as with partial pressure of oxygen: PAO2, what does the “A” indicate?

Answer 22

Alveolar gas

Question 23

Using a lowercase “a” such as with partial pressure of oxygen: PaO2, what does the “a” indicate?

Answer 23

Arterial gas

Question 24

What do we expect the relationship to be between the partial pressure of alveolar gas (PAO2) and the partial pressure of arterial gas (PaO2)?

Answer 24

They should be the same

Question 25

What relationship is described by Boyle's Law?

Answer 25

Pressure of a gas is inversely proportional to its volume [P1V1 = P2V2]

Question 26

Based on Boyle's Law, an increase in lung volume corresponds with a _______ in pressure, and air will _____ the lung.

Answer 26

Decrease; enter

Question 27

What kind of muscle(s) are/is the inspiratory muscles? A. Smooth muscle B. Skeletal muscle C. Cardiac muscle D. A and B

Answer 27

B. Skeletal muscle

Question 28

What units are utilized in the measurement of pressures in respiratory physiology? A. mm Hg B. cm Hg C. mm H2O D. cm H2O

Answer 28

D. cm H2O [note that we normalize atmospheric pressure to 0 cm H2O]

Question 29

What is the intrapleural pressure at rest? How does it change during inspiration?

Answer 29

About -5 cm H2O During inspiration, volume increases and intrapleural presure decreases to near -8 cm H2O

Question 30

As the thoracic cavity increases in size during inspiration, alveolar pressure (pressure within the alveoli) _________, which causes air to ______ the lungs

Answer 30

Decreases; enter

Question 31

At rest, alveolar pressure = _____ cm H2O At the end of inspiration, alveolar pressure = ____ cm H2O This is due to _______ in alveolar size

Answer 31

0 -1 Increase

Question 32

As the thoracic cavity increases in size with inspiration, pleural pressure (pressure within the pleural spaces _________

Answer 32

Decreases [starts negative, gets more negative]

Question 33

T/F: transpulmonary pressure should always be negative

Answer 33

False: The transpulmonary pressure should always be positive because the pleural pressure should always be negative, so subtracting a negative will give you a positive.

Question 34

How is transpulmonary pressure calculated?

Answer 34

Transpulmonary pressure = alveolar pressure - pleural pressure

Question 35

What is the transpulmonary pressure at rest?

Answer 35

5 cm H2O at rest

Question 36

Alveolar pressure increases during expiration due to recoil of the lungs, what does it increase to by mid-expiration?

Answer 36

+1 cm H2O

Question 37

What is the transpulmonary pressure at the following points in the respiratory cycle? 1. Rest 2. Mid-inspiration 3. End-inspiration 4. Mid-expiration

Answer 37

1. Rest = +5 cm H2O 2. Mid-inspiration = +5.5 cm H2O 3. End-inspiration = +8 cm H2O 4. Mid-expiration = +7.5 cm H2O

Question 38

_______ ________ = refers to the volume of air inhaled every minute

Answer 38

Minute ventilation

Question 39

A patient's respiratory volume is 14 breaths/minute (RR) and tidal volume is 500 mL per breath. What is their minute ventilation?

Answer 39

7000 mL/min = 7 L/min [this is the accepted normal value!]

Question 40

At the end of inspiration, what would pleural pressure be? ``` A. 0 cm H2O B. -5 cm H2O C. -8 cm H2O D. +5 cm H2O E. +8 cm H2O ```

Answer 40

C. -8 cm H2O

Question 41

Air flow into the lungs at the end of inspiration would be which of the following? A. +1 L/s B. 0 L/s C. -1 L/s D. -8 L/s

Answer 41

B. 0 L/s

Question 42

What would be the flow rate during a forced expiration? ``` A. +2 L/s B. 0 L/s C. -2 L/s D. -1 L/s E. +1 L/s ```

Answer 42

A. +2 L/s

Question 43

Transpulmonary pressure in the middle of inspiration would be which of the following? ``` A. +5 cm H2O B. +5.5 cm H2O C. +8 cm H2O D. -5.5 cm H2O E. -8 cm H2O ```

Answer 43

B. +5.5 cm H2O

Question 44

The 2 respiratory zones are the conducting zone (no gas exchange) and respiratory zone (gas exchange). In which zone would you find the most smooth muscle?

Answer 44

Conducting zone; important for dilating/constricting bronchioles

Question 45

What structures make up the key component of the respiratory zone?

Answer 45

Alveoli

Question 46

What is one of the more common tools for measuring respiratory volumes?

Answer 46

Spirometer

Question 47

What volumes and capacities cannot be measured by a spirometer?

Answer 47

Residual volume (RV) Functional Residual Capacity (FRC) Total Lung Capacity (TLC)

Question 48

Normal respiration consists of what 4 respiratory volumes?

Answer 48

Tidal volume Inspiratory reserve volume Expiratory reserve volume Residual volume

Question 49

Since residual volume cannot be measured by spirometry, what method (besides estimation) can be used to measure RV more precisely?

Answer 49

Helium dilution method

Question 50

________ are the sum of 2+ different combinations of respiratory volumes together

Answer 50

Capacities

Question 51

What factors influence respiratory capacity?

Answer 51

Size Gender Age Disease state

Question 52

What are the 4 respiratory capacities that can be calculated based on the different respiratory volumes?

Answer 52

Vital capacity (VC) Inspiratory capacity (IC) Functional Residual Capacity (FRC) Total Lung Capacity (TLC)

Question 53

What volume is used as a diagnostic tool and is a measure of how much air is blown out in the first second of forced expiration?

Answer 53

Forced Expiratory Volume in 1 sec (FEV1)

Question 54

_____% is a normal FEV1 A _______ in FEV1 would likely indicate obstructive respiratory disease A ______ in FEV1 would likely indicate retrictive respiratory disease

Answer 54

80 Decrease Increase

Question 55

_______respiratory diseases are considered diseases of the airways resulting in reduced air flow

Answer 55

Obstructive

Question 56

Which of the following is characteristic of obstructive lung disease? A. Reduced lung volume; difficulty exhaling B. Reduced lung volume; difficulty inhaling C. Reduced air flow; difficulty inhaling D. Reduced air flow; difficulty exhaling

Answer 56

D. Reduced air flow; difficulty exhaling

Question 57

_______ respiratory diseases are characterized by reduced expansion of lung parenchyma and decreased total lung capacity

Answer 57

Restrictive

Question 58

Which of the following is characteristic of restrictive lung disease? A. Reduced lung volume; difficulty exhaling B. Reduced lung volume; difficulty inhaling C. Reduced air flow; difficulty inhaling D. Reduced air flow; difficulty exhaling

Answer 58

B. Reduced lung volume; difficulty inhaling

Question 59

What type of respiratory disease is characterized by a reduced FEV1 and a decrease in the FEV1:FVC ratio?

Answer 59

Obstructive

Question 60

What type of respiratory disease is characterized by a reduction in both FEV1 and FVC, leaving the FEV1:FVC ratio either unchanged or elevated?

Answer 60

Restrictive

Question 61

What changes occur to residual volume and inspiratory reserve volume in obstructive disease?

Answer 61

RV increases IRV decreases

Question 62

______ _____ = regions of the lung that receive air but not blood, so no gas exchange takes place

Answer 62

Dead space

Question 63

What are the 3 types of dead space?

Answer 63

Anatomic Physiological Alveolar (subtype of physiologic)

Question 64

_________ dead space refers to space in the respiratory system other than alveoli

Answer 64

Anatomic

Question 65

_______ dead space refers to alveoli that receive air but not blood

Answer 65

Alveolar

Question 66

__________ dead space is basically alveolar dead space, meaning alveoli that receive air but not blood - so no gas exchange can occur

Answer 66

Physiologic

Question 67

In healthy individuals, what do you expect their physiological dead space to be?

Answer 67

Nearly zero

Question 68

At what point in the respiratory cycle does anatomical dead space air enter the lungs?

Answer 68

At the end of inspiration [this is the air that was left in the lungs at the end of previous expiration]

Question 69

How is anatomical dead space calculated?

Answer 69

It is typically estimated based on person's weight For example: 150 lb person = 150 mL of anatomic dead space

Question 70

How is physiologic dead space calculated?

Answer 70

(Arterial PCO2 - expiratory PCO2)/arterial PCO2

Question 71

How is minute alveolar ventilation calculated?

Answer 71

(Tidal volume - dead space) x frequency

Question 72

A 150 lb patient is breathing 12 breaths/minute. What is their minute alveolar ventilation rate?

Answer 72

4200 mL/min | 4.2 L/min

Question 73

A 200 lb person is breathing 20 breaths/min with a tidal volume of 750 mL. What is the minute ventilation rate?

Answer 73

15,000 mL/min [15 L/min]

Question 74

A 200 lb person is breathing 20 breaths/min with a tidal volume of 750 mL. Minute ventilation rate is 15,000 mL/min. What is their minute alveolar ventilation rate?

Answer 74

11,000 mL/min [11,000 L/min]

Question 75

A 67 y/o patient (6'2", 197 lbs) has been hospitalized with COPD. He is artificially ventilated at a respiratory rate of 23 breaths/min and a tidal volume of 900 mL. Total anatomical and physiological dead space has been calculated to be 300 mL. What is his alveolar ventilation? A. 17,600 mL/min B. 11,000 mL/min C. 13,800 mL/min D. 6,600 mL/min

Answer 75

C. 13,800 mL/min

Question 76

Which respiratory volume is the volume that can be inspired over and above the tidal volume?

Answer 76

Inspiratory reserve volume (IRV) [used during exercise]

Question 77

Which respiratory volume is the volume that can be expired after the expiration of a tidal volume?

Answer 77

Expiratory reserve volume (ERV)

Question 78

Which respiratory volume is the volume that remains in the lungs after a maximal expiration?

Answer 78

Residual volume

Question 79

How is inspiratory capacity calculated?

Answer 79

Tidal volume + Inspiratory Reserve Volume (IRV)

Question 80

How is functional residual capacity calculated?

Answer 80

Expiratory Reserve Volume (ERV) + Residual Volume (RV)

Question 81

______ ______ capacity = volume remaining in lungs after a tidal volume is expired

Answer 81

Functional residual

Question 82

Spirometery is a commonly used clinical method of measuring a person's functional residual capacity

Answer 82

False: FRC is calculated using residual volume, which cannot be measured by spirometry

Question 83

_____ capacity = volume of air that can be forcibly expired after a maximal inspiration

Answer 83

Vital

Question 84

How is vital capacity calculated?

Answer 84

Tidal volume + Inspiratory Reserve Volume + Expiratory Reserve Volume [can also do inspiratory capacity + expiratory reserve volume]

Question 85

What capacity represents the volume in the lungs after a maximal inspiration?

Answer 85

Total lung capacity (TLC)

Question 86

How is total lung capacity calculated?

Answer 86

It is the sum of all 4 lung volumes Can be calculated by taking Vital Capacity + Residual Volume OR: Inspiratory capacity + Functional Residual Capacity