Respiratory Mechanics and Compliance: Lecture 5

Question 1

True or False
To generate flow into the lungs we need to decrease the alveolar pressure

Answer 1

true

Question 2

Flow is measured by what?

Answer 2

Liters per second

Question 3

Why is there positive and negative flow?

Answer 3

• breath out is a positive flow
• breath in is a negative flow

Question 4

Is it possible to have 0 flow? if so when would that occur?

Answer 4

yes, between inspiration and expiration

Question 5

What happens to volume, flow, alveolar and pleural pressure during INSPIRATION?

Answer 5

Volume = increases
Flow = negative
Alveolar pressure = negative
Pleural pressure = negative increases negatively

Question 6

What happens to volume, flow, and alveolar and pleural pressure during EXPIRATION?

Answer 6

Volume = decreases
Flow = positive
Alveolar pressure = positive
Pleural pressure = increase, less negative

Question 7

What causes us to get winded?

Answer 7

• when we get hit in the gut that can temporality paralyze our phrenic nerve
• the phrenic nerve is the one that send the signals to our diaphragm to keep our breathing
• which is why we find it hard to breath

Question 8

During inspiration what does the diaphragm do?

Answer 8

it flattens and pulls everything down to allow the lungs space to expand

Question 9

What is pneumothorax?

Answer 9

fully uninflated lung collapsed lung

Question 9

What is the pleural pressure at the end of an expiration before an inspiration?

Answer 9

-4

Question 10

True or False
As we expand the lung in inspiration the recoil pressure will increase due to the elastic force

Answer 10

true

Question 11

What is the definition of the pneumothorax?

Answer 11

abnormal condition of air entering the pleural space

Question 12

What will happen if the pleural pressure somehow equals the alveolar pressure and the atmospheric pressure?

Answer 12

• the pressure gradient will no longer exist across either the lung wall or the chest wall
• with no opposing negative pressure the lung will collapse to its unstretched size

Question 13

How could we un-stretch our lungs “right now?”

Answer 13

breathing everything out, where the pleural pressure may become positive

Question 14

Is it possible for us to fully deflate your lungs?

Answer 14

naurrr

Question 15

What are the 2 common types of pneumothorax?

Answer 15

(a) Traumatic pneumothorax
- puncture wound in the chest wall
- complete puncture
ie. car accident

(b) Spontaneous pneumothorax
- a hole in the lung
ie. genetic

Question 16

If one of our lungs collapses will we die?

Answer 16

no

Question 17

True or False
Both types of pneumothorax can lead to a collapsed lung

Answer 17

true

Question 18

Airflow is dependent on what?

Answer 18

pressure gradients

Question 19

True or False
During inspiration, negative intrapleural and alveolar pressure is needed to move air into the lungs

Answer 19

True

Question 20

Inspiratory muscles generate the force required to change what?

Answer 20

volume to generate airflow

Question 21

During expiration which pressures will move air out of the lung once the inspiratory muscles relax?

Answer 21

recoil pressure

Question 22

The expiratory muscles are required to increase which pressures to empty the lungs?

Answer 22

intrapleural and alveolar pressures

Question 23

What is respiratory compliance?

Answer 23

How much air do we move for a given level of respiratory effort or pressure change?

Question 24

What does it mean if we have a highly compliant lung?

Answer 24

we do not need much effort to move lots of air

Question 25

What does it mean if we have a poorly compliant lung?

Answer 25

we need a lot of effort to move a little air

Question 26

True or False Compliance refers to how much effort is required to stretch or change the size of the lungs

Answer 26

True

Question 27

What happens to the compliance of the lungs when you have COPD?

Answer 27

- alveoli become stretchy

Question 28

What is COPD?

Answer 28

Chronic obstructive pulmonary disease - high lung compliance

Question 29

What is the equation for compliance?

Answer 29

change in lung volume/change (Palv - Pip) = change in volume/change Ptp

Question 30

recoil pressure is the same as what?

Answer 30

Transpulmonary pressure

Question 31

Why would we breathe at the linear area of the normal compliance curve? (sigmoid)

Answer 31

there is a specific level of inflation where it is the most efficient and easiest to breath

Question 32

What is fibrosis? (case of decreased compliance)

Answer 32

where the lung is stiff and scared

Question 33

True or False If we have a stiff lung we need to create large amounts of pressure to move little volume

Answer 33

True

Question 34

Increased compliance is equal to what kind of stiffness?

Answer 34

decreased stiffness

Question 35

Decreased compliance is equal to what kind of stiffness?

Answer 35

Increased stiffness

Question 36

True or False In highly compliant lung, for little changes in pressure they get large amounts of volume

Answer 36

True

Question 37

Why wouldn't everyone want highly compliant lungs?

Answer 37

because it would make breathing out harder, and we lose the elasticity and recoil pressure

Question 38

Why do we not need expiratory muscles to expire air?

Answer 38

because of the recoil pressure, aka transpulmonary pressure

Question 39

True or False For highly compliant lungs (emphysema) they need to recruit expiratory muscles to breath out

Answer 39

True

Question 40

The normal compliance of a lung in cmH20 is what?

Answer 40

2.0L

Question 41

Why do we breath where we breath?

Answer 41

it optimizes the work that we do

Question 42

What are the 2 factors affecting a lung's elastic recoil for lung and total respiratory compliance? (aka factors of compliance)

Answer 42

1. Highly elastic connective tissue in the lungs - any diseases that we mentioned will affect the connective tissue (stiff or floppy) 2. Surface tension of the alveoli - ability to balance out the alveolar pressure from each alveolus throughout the lung (premature babies do not secret surfactant so they cannot regulate the tension and pressure in the alveoli)

Question 43

What is pulmonary surfactant?

Answer 43

- complex mixture of lipids and proteins - made by type 2 alveolar cells - spreads out between water molecules in the fluid lining of the alveoli and lowers alveolar surface tension

Question 44

What are the 2 benefits of the pulmonary surfactant?

Answer 44

1. Reduces work of the lungs 2. Reduces recoil pressure of smaller alveoli more than larger alveoli (helps have a healthy compliance level)

Question 45

What is the law of Laplace?

Answer 45

Pressure = 2(tension)/radius

Question 46

Why would we want to breath at the lines "part" of the compliance curve? About the graph

Answer 46

there is less amount of pressure required to move air

Question 47

What is an example of a disease that causes highly compliant lungs?

Answer 47

Emphysema

Question 48

What is an example of a disease that causes poorly compliant lungs?

Answer 48

lung fibrosis

Question 49

True or False Compliance is the change in volume divided by the change in pressure

Answer 49

True

Question 50

True or False highly compliant lungs will have problems breathing out and poorly compliant lungs will have problems breathing it

Answer 50

True

Question 51

What helps regulate surface tension in the lung?

Answer 51

- surfactant

Question 52

What does surfactant do?

Answer 52

reduces surface tension in the alveoli and makes it easier to inflate

Question 53

What do Type 1 Alveolar cells do?

Answer 53

flat for gas exchange

Question 54

What do Type 2 Alveolar cells do?

Answer 54

secretes surfactant

Question 55

Without surfactant what would occur within two different sizes of alveoli?

Answer 55

- T1=T2 - Pressure would be higher in the smaller alveoli - Pressure would follow its gradient going from the smaller alveoli to the larger one causing the smaller one to collapse

Question 56

With surfactant what would occur within two different sizes of alveoli?

Answer 56

- Surface tension is proportional to radius - pressures will remain the same (P1=P2)