Harvey Flashcards
(99 cards)
1
Q
Although the diameter of the airways decreases as you get nearer the alveoli…what happens to the cross sectional area?
A
It increases a crazy amount!!
2
Q
How many generations make up the pulmonary tree? What is a generation?
A
23
A generation is a branching of the airways.
3
Q
The conducting zone consists of how many generations? What is this space considered? What is the volume of this space?
A
16 generations
150 mL
anatomic dead space (no gas exchange)
4
Q
The conducting zone ends at what structure?
A
terminal bronchioles
5
Q
The respiratory zone begins at what structure?
A
respiratory bronchioles
6
Q
The respiratory zone consists of how many generations? Its functional unit is called what? What is its approximate volume?
A
7 generations
functional unit: acinus
Volume HUGE like 3000mL
7
Q
What is one way to determine the lung’s functional volumes?
A
spirometer!!
8
Q
What is the approximate value of the tidal volume?
A
0.5 L
9
Q
What is the approximate inspiratory capacity volume?
A
2.5 L
10
Q
What is the approximate expiratory reserve capacity volume?
A
1.5 L
11
Q
What is the value of the residual volume?
A
1.5 L
12
Q
What is the vital capacity? What is the volume?
A
If you take a maximal inspiration…it is the maximum amount of volume you can expire from your lungs. Total lung capacity - Residual Volume.
4.5 L
13
Q
What is the functional residual capacity? What is its approximate volume?
A
After a tidal volume inspiration…the amount of volume left in your lungs.
3L
14
Q
What is inspiratory capacity? what is its approximate volume?
A
the total amount of air you can inspire
tidal volume + inspiratory reserve capacity
3L
15
Q
What is the approximate value of total lung capacity?
A
6.0 L
16
Q
What are the values that you can’t measure w/ spirometry?
A
residual volume
functional residual capacity
total lung capacity
17
Q
When you are lying down the residual volume decreases. Why?
A
b/c the abdominal contents push up on your diaphragm & allow you to exhale more air.
18
Q
What are 3 methods for measuring FRC since spirometry doesn’t work?
A
Nitrogen Dilution
Helium Dilution
Plethysmography
19
Q
What equation is nitrogen dilution based off of?
A
C1V`1=C2V2
20
Q
What concept is plethysmography based off of?
A
Boyle’s Law
21
Q
What are the 2 types of inspiration?
A
Positive Pressure Breathing
Negative Pressure Breathing
22
Q
What is positive pressure breathing & when does it occur?
A
The air on the outside is above atmospheric pressure & the air in the alveolar space is @ atmospheric pressure & then air can flow in b/c of the pressure difference.
**this is used w/ mechanical ventilation in the hospital. You kinda force the air in.
23
Q
What is negative pressure breathing & when does it occur?
A
This is where you expand the chest cavity to make the intrapleural pressure negative & the air on the outside is @ atmospheric pressure & it can flow in b/c of the pressure difference.
**this is how most of us breathe!!
24
Q
In a healthy person, what are the most important muscles for inspiration? If the person is healthy–>is inspiration active or passive?
A
diaphragm: contracts & pushes down (expands volume)
external intercostals: pull the ribs upward (expands volume)
Active process
25
What are the accessory muscles of inspiration & when are these necessary?
Scalenes: lift the first 2 ribs
Sternocleidomastoid: raises the sternum
**used during exercise or like in patients w/ COPD
26
What are the main muscles of expiration in a healthy person? Is this normally an active or passive process?
No muscles normally b/c it is usu a passive process.
27
What happens to expiration when a person is exercising?
It becomes an active process & you use accessory muscles.
28
What are the important muscles of active expiration?
abdominal muscles: push cavity inward (rectus abdominis, external & internal obliques, transverses abdominis)
Internal Intercostals: pulls the rib cage down
29
At the end of tidal expiration, what is the pressure difference b/w the atmosphere & the alveoli?
0, therefore no air flow.
30
At the end of tidal expiration is there a negative pressure anywhere in the lung?
Yes, there is a negative intrapleural pressure. Of about -5cmH2O.
31
What creates the negative intrapleural pressure of the lung at the end of tidal expiration?
the combination of the elastic recoil of the lungs "wanting" to go inward & the elastic recoil of the chest wall "wanting" to go outward.
32
What is the equation for transpulmonary pressure?
Transpulmonary Pressure = Alveolar pressure - Intrapleural Pressure
33
At the end of tidal expiration, what is the transpulmonary pressure?
+5 cmH2O
34
At the end of tidal expiration, what is the volume that is in the lungs?
FRC
35
What is another name for transpulmonary pressure?
elastic recoil pressure
36
What causes a change in lung volumes?
changes in transpulmonary pressure
37
In detail, explain what causes air to flow into the lungs with inspiration.
Expand the chest with inspiratory muscles.
Higher chest volume means lower chest pressure (negative w/ respect to the atmosphere).
Now: the alveolar pressure < atmospheric pressure
Intrapleural pressure is even more negative (-8)
The transpulmonary pressure is even more positive (+7)
This allows air to flow in.
38
Changes in transpulmonary pressure is due to changes in what other 2 pressures?
Transrespiratory
| Transthoracic
39
What is the equation for transrespiratory pressure?
Transrespiratory Pressure = Alveolar Pressure - Atmospheric Pressure
40
What is the equation for transthoracic pressure?
Transthoracic Pressure = Intrapleural Pressure - Atmospheric Pressure
41
When does the intrapleural pressure finally plateau & become more positive?
At the end of inspiration.
42
What does flow correspond w/?
it corresponds with alveolar pressure-->they both peak together...
43
When do the alveolar pressure & flow peak together?
At the middle of inspiration.
44
Why do the alveolar pressure & flow peak at all?
b/c as the chest volume expands air flows in & lowers the volume at the same time. This corresponds to a point in the middle that starts to reverse the inspiration.
45
What is compliance?
the change in volume for a given change in pressure
46
What is the significance of the slope in a pressure volume loop?
It corresponds to the compliance.
| It reflects the elastic nature of the lung.
47
When you have higher compliance, you have less ______.
Higher Compliance
| Less Elastance
48
B/c the slope of the pressure volume loop changes during inspiration & expiration....what else changes throughout this process?
compliance changes...
49
What does emphysema do to the pressure volume loop? Why?
It makes the slope steeper. This means that it is more compliant. This is b/c you lose the elasticity of your lung when you have emphysema.
50
What is hysteresis? What is responsible for this?
The difference b/w the inspiration & expiration lines of the pressure volume loop.
Surface tension is responsible for this.
Surfactant decreases this effect.
51
The lung is less compliant at high/low volumes. This corresponds to what type of slope?
Less compliant @ high lung volumes. Milder slope.
52
Does compliance increase or decrease w/ the following pulmonary diseases:
emphysema
pulmonary fibrosis
Emphysema: compliance increases
| Pulmonary Fibrosis: compliance decreases
53
What is responsible for the elastic properties of the lungs?
Elastin & collagen fibers that surround the bronchi & alveoli
54
When there is no transpulmonary pressure gradient...what is the volume in the lung?
not zero...
55
What is surface tension? What increases it?
the attractive forces b/w molecules
| an air-liquid interface increases it.
56
What happened to the pressure volume loop when the lung was inflated w/ saline solution?
Its slope became steeper & the hysteresis disappeared.
This is b/c w/ saline soln there is no surface tension.
Thus, compliance increases (steeper slope) & no hysteresis (caused by surface tension).
57
What does surfactant do to the pressure volume loop?
```
It reduces surface tension.
Steeper Slope
Higher Compliance
Lower elastance
Lower surface tension
Less Hysteresis
```
58
Which has a greater surface tension & pressure: a small alveolus or a large alveolus?
a small alveolus
59
Without surfactant, what happens to the small alveoli?
the greater pressure in the small alveoli causes the air to flow out of them into the larger alveoli. The small alveoli collapse.
Surfactant reduces surface tension & keeps this from happening.
60
What size of alveoli does surfactant have a greater effect on?
small alveoli-->greater effect!!
61
What cells secrete surfactant?
Type II alveolar cells or Type II pneumocytes
62
What is the main component of surfactant? What is its nature?
DPPC: dipalmitoyl phosphatidylcholine
| amphipathic
63
What are 2 diseases that involve a lack of surfactant?
Infant Respiratory Distress Syndrome
| Acute Respiratory Distress Syndrome
64
What is infant respiratory distress syndrome?
born premature w/o surfactant.
| Surfactant doesn't develop until 4 month of gestation, & isn't fully functional until the 7th month.
65
What is acute respiratory distress syndrome?
a lack of surfactant due to hypoxia or hypoxemia.
66
What happens to you when you lack surfactant?
Decreased Compliance
Increased tendency of the alveoli to collapse
Harder to breathe!! Poor thing...
67
What happens to intrapleural pressure & the size of the lung & chest wall w/ a pneumothorax?
Lung is punctured & pressures everywhere (including the intrapleural pressure) equalize w/ the atmospheric pressure.
The lung & chest wall can no longer balance each other out so the lungs collapse & the chest wall expands.
68
What determines functional residual capacity?
a balance b/w outward elastic recoil of the chest wall & the inward elastic recoil of the lungs...
69
Which has the lowest compliance?
Lung
Chest Wall
Lung + Chest wall (working together)
Lung & Chest Wall (working together)
least steep slope
most elastic
70
What does emphysema do to compliance? Elasticity? FRC?
Compliance increases (more steep)
Elasticity decreases
FRC higher
71
What does fibrosis do to compliance? Elasticity? FRC?
Compliance decreases (less steep)
Elasticity increases
FRC lower
72
b/c of gravity...there is difference in the intrapleural pressure at the base of the lung vs. at the apex of the lung...Where is the pressure the least negative?
Base of the lung.
73
Where in the lung are the alveoli the most compressed?
near the base of the lung...
74
Is the slope steeper at the base of the lung or the apex of the lung? What does this mean for compliance?
Steeper at the base of the lung.
| Higher compliance here.
75
Where is there more ventilation of the lung? At the base or the apex?
At the base of the lung.
76
If you are operating at lower lung volumes...how does that change the distribution of compliance?
In this case...the base of the lung is less compliant than the apex of the lung.
77
What are the 2 main sources of resistance to airflow in the lungs?
Elastic Resistance
Non-elastic resistance
**mainly elastic
78
What are the 2 sources of non-elastic resistance in the lung?
Airflow
| Viscosity (friction b/w the lungs & the chest wall)
79
What are the 2 types of airflow?
Laminar & Turbulent
80
What are the characteristics of laminar flow?
faster in the middle & slower on the sides. peaceful flow...like down a river : )
81
What are the characteristics of turbulent flow?
just crazy chaos & churning...like kayaking down some rapids...makes it hard to get air out of the lungs.
82
What has the greatest effect on airflow, according to Poiseuille's Law?
the radius of the airway...fourfold difference...
83
What is the purpose of the Reynold's Number?
the higher the Reynold's number the more likely the flow will be turbulent.
Re=2rvd/n
84
Describe the 3 conditions that usu cause turbulent flow.
High velocity of airflow
Large radius of airway
Dense gas being inhaled
85
Where is turbulent flow most likely to occur?
trachea during exercise
86
Where is laminar flow most likely to occur?
terminal bronchioles
87
Where does airway resistance peak? Where is it lowest?
It peaks at the medium-sized bronchioles.
It is lowest @ the terminal bronchioles.
**even tho the radius is lowest, the cross sectional area is the highest & the resistance is therefore the lowest...
88
Breathing at high lung volume causes high/low resistance to airflow?
Low resistance--this is why people w/ certain pulmonary diseases compensate by breathing large volumes.
89
What does sympathetic stimulation of the lung do to airway resistance?
it decreases it b/c of beta 2 stimulation (dilation)
90
What does parasympathetic stimulation of the lung do to airway resistance?
It increases it b/c of the muscarinic receptors & constriction
91
What do inflammatory mediators such as leukotrienes & histamine do to resistance?
They increase it. These are the things that are released during an asthma attack.
92
T/F Respiratory effort can affect the resistance to airflow.
TRUE
93
What is the difference b/w respiratory effort on inspiration & expiration?
Inspiration: increase your effort-->increase your flow
Expiration: increase your effort-->nothing special will happen to your flow. : (
**the expiratory flow rate is constant
94
```
What's the deal w/ the following during pre-inspiration:
intrapleural pressure
alveolar pressure
transpulmonary pressure
transpulmonary pressure gradient
```
intrapleural pressure: negative (-5)
alveolar pressure: =atmospheric (uniform)
transpulmonary pressure: positive (+5)
transpulmonary pressure gradient: uniform
95
```
What's the deal w/ the following during inspiration:
intrapleural pressure
alveolar pressure
transpulmonary pressure
transpulmonary pressure gradient
```
intrapleural pressure: more negative (-7)
alveolar pressure: negative (less negative more near the mouth)
transpulmonary pressure: not uniform (more positive closer to the mouth)
transpulmonary pressure gradient: not uniform
96
```
What's the deal w/ the following during pre-expiration:
intrapleural pressure
alveolar pressure
transpulmonary pressure
transpulmonary pressure gradient
```
intrapleural pressure: quite negative (-8)
alveolar pressure: = atmospheric
transpulmonary pressure: positive (+8)
transpulmonary pressure gradient: uniform again!!
97
```
What's the deal w/ the following during forced expiration:
intrapleural pressure
alveolar pressure
transpulmonary pressure
transpulmonary pressure gradient
```
intrapleural pressure: super positive (+30)
alveolar pressure: very positive--gradient will less positive towards the mouth
transpulmonary pressure: dramatic
transpulmonary pressure gradient: can become negative as you move toward the mouth
98
What happens when the transpulmonary pressure becomes negative in forced expiration?
constriction of airways (small diameter & huge resistance)
| **the harder you try the more likely your airways are to collapse.... : (
99
In patients with emphysema they have reduced _____ & this compromises their _____ pressure. Thus, they don't have trouble w/ inspiration, but only expiration. To combat this you use what technique?
reduced elasticity
transpulmonary pressure (less recoil)
Pursed lips increase resistance of the airway & allow them to breathe out their air.
