Lecture 1: Pulmonary Physiology (Mechanism of Breathing/Lung Volumes) Flashcards
1
Q
List the 3 things pertaining to the anatomy of the lungs that make it unique
A
- The lungs even in close confines of the chest cavity allow diffusion because it maximizes the surface area of airways (conducting zone), alveoli (respiratory zone) & pulmonary capillaries
- Close association b/w alveoli & pulmonary capillaries (=short diffusion distances of O2 & CO2 at alveolar-capillary membrane)
- 1&2 helps maximize gas exchange of O2 & CO2 at the alveolar-capillary membrane within the closed cavity (V-dot O2&V-dotCO2)
V-dotO2: Volume of O2 in ml and the rate its inhaled
V-dotCO2: Volume of CO2 in ml and the rate its exhaled
2
Q
What is the main role of the respiratory muscles?
A
Force, displacement
3
Q
What occurs due to the interaction of the respiratory muscles and lung & chest wall?
A
Interaction brings air in and out of the lungs which allows for gas exchange to occur (Ventilation)
4
Q
Decrease ventilation:
Increase ventilation:
A
Decrease ventilation: increase CO2
Increase ventilation: decrease CO2
5
Q
What do these symbols stand for concerning the lung?
- C
- F
- P
- Q
- Q-dot
- R
- S
- V
- V-dot
A
- C=concencentration of gas in the blood
- F=Fractional concentration in dry gas
- P=Pressure or partial pressure (fractional [ ] x Atmospheric pressure)
- Q= Volume of Blood
- Q-dot=Volume of blood per unit time (rate)
- R=Respiratory exchange ratio
- S=Saturation of hemoglobin with O2
- V=Volume of gas
- V-dot=Volume of gas per unit time (rate)
6
Q
What phases does capital sunscript and lowercase subscript represent?
A
- Capital subscript: Gas Phase
- Lowercase subscript: Blood Phase
7
Q
What are these symbols measuring?
- V(A)
- V(T)
- V(D)
A
- V(A)=Alevolar volume (ml or L) of gas in alveoli
- V(T)= Tidal volume (ml or L): volume of air you inhale or exhale
- V(D)=Dead space volume
All gas phase measurements
8
Q
What are these symbols measuring?
- P(A)O2
- P(a)O2
- P(v)O2
- P(E)CO2
A
- P(A)O2=Partial pressure of oxygen in the alveoli
- P(a)O2=Partial pressure of oxygen in arterial blood
- P(v)O2=Partial pressure of oxygen in venous blood
- P(E)O2= Partial pressure of CO2 in the End Title
End Title= Expired breath (air coming out of you)
9
Q
What is the general pathway of air entering the lungs?
A
Air flows into the trachea–>divides into 2 zones—>the 2 zones divide into 2 more zones—>zones keep dividing
10
Q
What is each divison of the lung starting from the trachea called?
A
Zones
11
Q
Explain the Dichotomous Branching airways
A
- Multiple airways conduction down to deeper parts of the lung including the Conducting Zone and Respiratory Zone
Dichotomous: each branch divides into 2 divisions
12
Q
What are the Conduction Zones? and what are their special features?
A
- Zones (generations) 0-16
- No alveoli
13
Q
What is the Funtion of the Conducting Zone (Z-16)?
A
To lead air into the gas exchane areas (Z17-23)
14
Q
What happens in Zones 0-16 d/t the presence of NO alveoli?
A
NO gas exchange
15
Q
What zones are the terminal bronchioles?
A
Z5-16
16
Q
What are the terminal bronchioles (Z5-16)?
A
The smallest conducting airways w/out alveoli
17
Q
How does air flow in the Conduction zone (Z0-16)?
A
Bulk Flow (pressure gradient) via Boyle’s Law
The nose and mouth drive air into the body
18
Q
What is the relationship b/w pressure and volume as explained w/ Boyle’s Law?
A
- As volume increases, pressure decreases
- As volume decreases, pressure increases
19
Q
What is the equation that helps explain bulk flow?
A
V-dot ⍺ 𝚫P/Raw
20
Q
Explain the relationships of the bulk flow equation
V-dot ⍺ 𝚫P/Raw
A
- V-dot is directly related to 𝚫P and inversely related to Raw
- V-dot: volume of gas per unit time (airflow in)
- 𝚫P: Change in pressure gradient (from nose & mouth down the the terminal bronchioles)
- Raw: Airway Resistance
21
Q
What is the equation for 𝚫P in bulk flow?
𝚫P=change in pressure
A
- 𝚫P=P(B)-Pairway
- P(B)= barometric pressure (or atmospheric pressure) in the room
- Pairway= pressure in the airway
22
Q
What are the Respiratory Zones and explain their function?
A
- Zone 17-23, Increased surface area
- Contains Alveoli
- Function: where gas exhange occur
23
Q
What is the composition of air in the Respiratory Zones (Z17-23)?
A
The air inhaled, mixed w/ residual gas from the previous breath
24
Q
How does air flow in the Respiratory Zones (Z17-23)?
A
Diffusion
25
What drives diffusion in the respiratory zones (Z17-23)?
Partial pressure gradient of O2 and CO2
26
How are O2 and CO2 transported by diffusion in the Respiratory Zones (Z17-23)?
* Partial pressure gradient will drive **diffusion of O2** into the alveoli which then is transported to the blood
* Partial pressure gradient will drive **diffusion of CO2** in the opposite direction. Higher in the blood coming to the lungs from the veins→diffuse into alveoli then exhaled
27
What is the graph below showing?
The Increaing Total Cross Sectional Area (cm3) from the Conducting Zone (Z0-16) to the Respiratory Zone (Z17-23)
28
What causes the increasing total surface area from the conducting zone to the respiratory zone?
Branches begin to run parallel to each other which increases surface area in terms of airspace
29
R(aw) greater when breathing through?
## Footnote
R(aw)=resistance of airway
Nose
30
What is a major site of R(aw)?
Large airways > 2mm
31
What is this graph below showing?
* Resistance: Increasing initially as branches narrow for Z0-5.
* Z6 branches begin run parallel to each which increases surface area
* Increase in surface area causes a large drop in resistance (d/t brances adding up as the inverse: 1/Rtotal= 1/R1+1/R2+...)
32
What is the highest resistance zone?
Z5
33
What zones are the problem areas for diseases like asthma and bronchitis?
Z0-5 where resistance is increasing since the branches are narrow and NOT parallel
34
What happens with the volume of the thoracic cavity when the diaphragm contracts?And the outcome of that?
Volume of thoracic cavity increase thus sucking air into it so the alveoli expanding and expanding each other
35
What are alveoli?
Air sacs in the lung that allow for gas exchange
36
What is the thin wall surrounding alveoli made of? And what is the function?
* Pulmonary capillaries
* Function: facilate O2 uptake by RBCs and CO2 offloading from the blood into the alveoli
37
What lines each of the alveoli and what does it form?
A fluid that mix with air to form **surface tension**
38
What does the surface tension try to do to the alveoli and what is the outcome?
Surface tension is trying to squeeze the cell in and have it collapse to a smaller volume and the counterinteraction with the air in the alveoli gives the lungs it elasticity
39
What gives the lungs its elasticity?
Surface tension (fluid+air)
40
What cell in the alveoli is involved with surface tension and what does it do?
Type II (surfactant-secreting) cell which **decreases** surface tension
41
What happens when you increase fluid too much?
The membrane becomes more thicker and you decrease in O2 diffusion since there is a bigger gap between the pulmonary capillaries and the air sac
42
Why would a premature baby lungs have no elasticity?
A premature baby will have a lack of Type II cells which secrete surfactant. A lack of surfactant will increase the surface tension
43
What are the mechnical aspects of breathing or in other words how does the pulmonary pump occur?
## Footnote
HIGH yield
* A change in the cross-sectional dimensions of the thoracic cavity (via contraction of respiratory muscles) are transmitted to the lungs
* **Boyle's law** which states: that lung volume increases and alveolar pressure decreases during **inspiration.** And during **expiration** lung volume decreases and alveolar pressure increases
* Air enters the upper airway by bluk flow (air flows from higher to lower pressure: ↓P=↑air)
44
What is the main muscle for breathing (inspiration) and what innervates it?
The Diaphragm innervated by the Phrenic nerve (C3,4&5)
45
What is the term for at rest breathing?
Euphea
46
What are the accesory muscles for Inspiration?
* **External Intercostals** (most important)
* Sternocleidomastids
* Trapezius
* Scalenus
47
What is happening to the Diaphragm (inspiratory muscle) when you breathe in?
* **Diaphragm**: Contracts and drops down, lung adheres to the diaphragm and pull down too which increases volume and decreases pressure
48
What is happening to the External Intercostal (inspiratory muscle) when you breath in?
* **External Intercostals**: Causes a "bucket-handle rotation" which pulls ribs up and out to further pull out the lungs to decrease pressure which makes a larger pressure gradient to drive more air into the lungs to increase breath rate.
49
When are the muscles Sternocleidomastids, Trapezius and Scalenus used in inspiration and explain there function?
* Only used on really high rates of breathing
* Function: Pull upper part of ribcage up to allow lungs to pull further out
50
What are muscles for Expiration? and what innervates them?
* **Interal Intercostal** (most important)
* Rectus Abdominus
* External Oblique
* Interal Oblique
* Transversus Abdominus
* Innervated by motor neurons
51
What is happening to the Internal Intercostals during Expiration?
They contract and pull the ribs back in which squeezes the gas in the lungs. This causes a increase in pressure and decrease in volume so more air can be pushed out
52
When are the abdominal muscles (Rectus Abdominus, External Oblique, Interal Oblique andTransversus Abdominus) used in expiration?
Used for Forced Expiration (e.g. Heimlich Maneuver)
53
What is the mechanism of the Abdominal expiratory muscles?
* When these muscles are contracted, increases the pressure in the lungs greatly.
* Mainly used in forced expiration
## Footnote
Abdominal muscles: Rectus Abdominus, External Oblique, Interal Oblique and Transversus Abdominus
54
Describe the action of the abdominal muscles during a Heimlich Manuever
When something is stuck in airway, push into the abdominal muscles. That force pushes the organs and diaphram up into the lungs. This cause volume to decrease and pressure to increase (Forced expiration)
## Footnote
Abdominal muscles: Rectus Abdominus, External Oblique, Interal Oblique and Transversus Abdominus
55
Expiration is usually ____________ during resting breathing (a.k.a. eupnea or eupheic ventilation)
Passive
56
Inspiration is an _________, because we have to do ________.
* Active Process
* Work
57
What work is done during inspiration?
Actively contract the respirtory muscles to generate the pressure gradient b/w the nose, mouth and airway, also across the wall of the lungs
58
When are expiratory muscles active?
## Footnote
NOTE: Expiratory muscles are normally passive
* During increased ventilation
* Expulsive maneuvers
* In patients with lung diseases
59
Are the lungs anatomically connected to the thoracic wall or diaphragm? explain
* NO, because there is a **visceral pluera that lines the chest wall** and a **partial pleura that lines the lung**. In between them is a thin flim of fluid called the **intrapleural space**
60
What does the analogy of two wet glass slides help explain with the lungs, chest wall and intrapleural space?
The chest wall and lungs slide against each other d/t the intrapleural space like two slides w/ fluid between them in the microbiology lab
61
What is the graph below showing? And what is measured by the:
* x-axis
* y-axis
* blue arrow (line)
* red arrow (line)
* Black arrow (line)
* Graph is showing what occuring in the breathing cycle
* x-axis: time
* y-axis: volume
* Blue arrow (line): Inspiration
* Red arrow (line): Expiration
* Black arrow (line): Resting Volume=End Expiratory Volume=Functional Residual Capacity (FRC)
62
What is the total lung capacity (TLC)?
Inhaling as much as you can until you cannot inhale anymore (max. volume of air in the lungs)
63
What is the resting volume?
* It is the rest zone between breathes (expiration and inspiratio)
* The lung deforms chest wall and the chest wall deforms the lung, they're equal and opposite so the are at equilbrium @ FRC
* Can also be called End Expiratory Volume or FUNCTIONAL RESIDUAL CAPACITY (FRC).
64
What are the other names for resting volume?
* End Expiratory Volume
* FUNCTIONAL RESIDUAL CAPACITY (FRC)
65
Why does the lung move with the chest wall when the respiratory muscles contract?
Because of the:
* **visceral pleura** (covers the lungs)
* **parietal pleura** (lines the chest wall & diaphragm)
* **Intraplueral space** (∼2 ml of fluid)
* **Intraplureal pressure (Ppl)** (∼-5 cm H2O=-3.7 mmHg)
66
How is the intraplueural pressure (Ppl) determine?
By the chest wall wanting to expand outwards and the lungs wanting to recoil inward d/t surface tension. These actions pull against each other to create the Ppl which is ∼-5cm H2O @ room temperature
67
Why is the Ppl subatmospheric?
## Footnote
Subatmospheric- less than atmospheric pressure
1. The lungs want to contract to a smaller volume d/t its elasticity (pulmonary capillaries & alveolar tissues) and surface tension
2. The chest wall wants to expant to a larger volume d/t elasticity
68
What is the outcome of the lung and chest wall forces @ FRC?
## Footnote
FRC: Functional Residual Capacity
* These two forces are equal and opposite
69
What does the opposing forces of the chest wall and lungs do to the intrapleural space?
* Opposing forces 'increases volume' of intrapleural space and 'decreases pressure' within the interaplueral space (below atmospheric pressure)
* When these forces pull, a negative pressure, or vacuum is created
70
What is Ppl at FRC?
∼-5 cm H2O
71
What does a negative Ppl mean for the resting volume of the lungs?
It opposes the natural tendency of the lungs to collapse and the chest wall to spring out
72
In the image below explain:
* Why P(atm)=P(B)=0
* What P(aw) equals and why
* What Ppl equals and why
* Why P(A)=0
## Footnote
* P(atm): atmospheric pressure
* P(B)=Barometric pressure
* P(aw)=Airway pressure
* Ppl=intrapleural pressure
* P(A)=pressure in the lungs
* Atmospheric pressure (P(atm))= Barometric pressure (P(B))=0 d/t the lungs being at rest
* Airway pressure (P(aw))=0 b/c at rest there is no airflow (@ the end of inspiration and end of expiration)
* Intrapleural pressure (Ppl)= -5 cm H2O because the lungs are at FRC/resting volume
* P(A)=0 because there is no airflow into the lungs
73
What determines the bulk flow of air in an out concering this image?
## Footnote
* P(atm): atmospheric pressure
* P(B)=Barometric pressure
* P(aw)=Airway pressure
* Ppl=intrapleural pressure
* P(A)=pressure in the lungs
The pressure gradients
* P(atm)/P(B)=Atmospheric/Barometric pressure
* P(aw)= Airway pressure
74
What is the equation for bulkflow through conducting zone?
P(B)-P(aw)=V airflow=(bulkflow through conducting zone)
75
What is the equation for transpulmonary/transmural pressure? And what is it measuring?
* P(L)= P(A)-Ppl
* Used to calculate the pressure in the lunngs minus the pressure around the lung which is the intrapleural space
76
What is the Transpulmonary/transmural pressure P(L) at FRC and explain the meaning of each number in the equation?
At FRC (@ at the end of expiration)
* Equation: **P(L)**=P(A)-Ppl
* Solution: 0-(-5) = **+5 cm H2O**
* P(A)=0 b/c at FRC there is no airflow (it is the midpoint of a breathing cycle)
* Ppl= -5 cm H20 b/c that is intraplueral pressure at FRC
* P(L)= +5 cm H2O which is the pressure that is needed to keep the lungs open at rest
77
What is the transpulmonary pressure P(L) during early inspiration? and explain the change for P(L) at FRC?
During early inspiration
* Equation: **P(L)**=P(A)-Ppl
* Solution: (-1)-(-6.5)=**+5.5 cm H2O**
* P(A)= -1 b/c airflow enters the lungs which increases V and decreases P (that is why P(A) is negative
* Ppl= -6.5 b/c intrapleural pressure deccreases d/t pressure dropping
* P(L)= +5.5 cm H2O b/c transpulmonsry pressure increases when their is airflow into the lungs
## Footnote
NOTE: Ppl drops first and P(A) follows after
78
During early inspiration is there airflow into the lungs. Why?
* YES b/c Patm>P(A)
* Patm remains 0 while P(A) becomes -1 d/t increased volume of airflow which causes decrease in pressure
79
What is the transpulmonary pressure P(L) during the end of inspiration?
End of Inspiration
* Equation: **P(L)**=P(A)-Ppl
* Solution: (0)-(-8)=**+8 cm H2O**
* P(A)= O b/c there is no more airflow in the lungs. Lungs have reached max. volume
* Ppl= -8 b/c lung capcity is still changing even w/out active airflow. Increased recoil=decreased Ppl
* P(L)= +8 cm H2O b/c transpulmonsry pressure increases when the air in the lungs are at max. volume
80
During the end of inspiration is there airflow into the lungs. Why?
* NO b/c Patm=P(A)
* P(A) returns to d/t the lungs being at max. volume at the end of inspiration
81
What is the transpulmonary pressure P(L) during expiration?
During Expiration
* Equation: **P(L)**=P(A)-Ppl
* Solution: (+1)-(-6.5)=**+7.5 cm H2O**
* P(A)= +1 b/c lung pressure increase d/t low lung volume (lung is emptied during expiration)
* Ppl= -6.5 b/c continual decrease from Ppl at the end of inspiration (Ppl:-8) and lung pressure increase
* P(L)= + 7.5 cm H2O b/c transpulmonsry pressure decreases when the air in the lungs is being expired
82
What is the direction of airflow during expiration and why?
* Airflow out of the lungs
* Patm
83
List the step for Normal Eupnea Breathing Cycle
## Footnote
Also known as the pressure, airflow and volume changes during quiet breathing
1. Inspiratory muscles contract
2. Thoraic cavity expands
3. Intrapleural space becomes more negative
4. The lungs expand
5. Alveolar pressure becomes subatmospheric
6. Air flows into the lungs until alveolar gas pressure equals atmospheric pressure
7. Inspiratory muscles relax
8. Process reverses (for expiration)
84
Match Expiration, Inspiration, FRC to:
* PA=PATM
* PAPATM
* **FRC:PA=PATM** -No air flow, lung at rest
* **Inspiration: PAPATM**- Decreasing volume so the PA (pressure in alvelolar) increases above PATM
85
Does intrapleural pressure (Ppl) become more negative or positive during deep inspiration?
More negative
86
Does intraplueral pressure (Ppl) become more negative or positive during deep expiration?
More positive
87
When is Intrapleural pressure (Ppl) increasing and decreasing?
* Increasing: Expiration
* Decreasing:Inspiration
88
The graph below shows changes in intrapleural pressure (Ppl) during maximum inspiration and expiration. Explain points a,b, and c.
* **Point a** : Eupenic breathing (normal quiet breathing; red:inspiration, blue:expiration)
* **Point b (red)**: Forced Inspiration; max. TLC (total lung capacity)
* **Point b (bue)**: Forced expiration
* **Point c**: forced exhale where PL along the conducting zone gets smaller and smaller. Airway doesn't collapse d/t cartilage but they begin to narrow which increases resistance. This makes it hard for all the air to blow out and why lungs are never empty
## Footnote
* Ppl=-5 cm H2O; normal @ FRC
89
What is Pneumothorax and what causes it?
An opening in the chest wall caused by either a gun shot wound, stab wound, auto accident. etc
90
Explain what happens during pneumothorax?
At FRC an opening in the chest wall exposes the intraplueural space to atomspheric pressure
91
What are the consequences of pneumothorax?
* Loss of Negative intrapleural pressure, Ppl (Ppl=PB)
* Collapse of the ipsilateral lung (affected side)
* Decreased venous return to heart during both Inspiration & Expiration
* Venoarterial shunting (i.e. ventilation/perfusiion mismatch), and patient becomes cyanotic
* During Inspiration, mediastinum (diving wall b/w left and right lung) shifts to compress the uninvolved lung, which decreases lung volume on the uninjured side
* Consequently, the patient is in severe respiratory distress
92
Explain the treatment of Pneunothorax when it is a:
* Small hole
* Medium hole
* Large hole
* Small: Resolves on its own
* Medium: Reinflate using a small needle in intrapleural space (needle carefully remove the air to try to re-establish the vacuum, get the tissue adhering again to the chest wall)
* Large: Insert chest tube for several days to try to re-establish that lung to its appopriate volume
93
What was the use of the iron lung, explain how it works?
* Used during polio (disease attacked respiratory muscles)
* Acts as a chest wall with cold air-> decreases pressure and increase lung volume
* Decreases body pressure=increases lung volume (inhale)
* Increase body pressure=decreases lung volume (exhale)q
94
Explain the relationship of Pressure and Volume defined by Boyle's Law
Pressure (P) and Volume (V) of a gas mixture are inversely proportional to each other
95
Explain the relationship of pressure and volume using the World War II pressurized plane
* **a**: Plane is 8000 ft in the air and pressure is not regulated
* **b**: from 8000 ft to 30,000 ft pressure is regulated to feel like 8000 ft
* **c**: After 30,000 ft regulation of pressure stopped but maintain a pressure differential of about 6 1/2 pounds oer square inch inside relative to outside
* Takeaway: Increased pressure inside and decreased pressure outside allows plane to increase ft of flight
96
What are the Static Properties of the Lungs and Chest wall? And what does it tell us?
* Compliance
* Elastic recoil (how elastic the lung is)
* Tells is how well the lungs move
97
What are the Dynamic Properties of the Conducting Zone? And what does it tell us?
* Flow
* Resistance
* Tells how well the air flows
98
Define Work of Breathing
Is a measure of how hard the respiratory muscles must contract to inflate the lungs during Inspiration
99
What is the equation for work of breathing?
* Work=𝚫Ppl x 𝚫V
* 𝚫Ppl: Change in intraplueral pressure
* 𝚫V= volume change given inside the lung
100
What factors need to be overcome during Inspiration?
* Elastic recoil forces of the lung, chest wall, and alveolar surface tension forces
* Airway resistance
* Pulmonary resistance (=viscous tissue resistance)
101
Define Elastance (elasticity)
A property of matter that:
* causes it to return to its resting state after deformation by an external for
or
* causes it to resist stretch
102
Define compliance (C). What causes it?
Elastic recoil of the lungs due to elastic tissue and alveolar surface tension
103
What is the compliance (C) equation?
C=1/Elastance=𝚫V/𝚫P
* 𝚫V: change in lung volume
* 𝚫P: change in pressure either d/t intrapleural pressure (Ppl) or transpulmonary pressure (P(L))
104
Below is a Static P-V relaxation curve. What is it measuring and how?
* Measure the pressure and volume of the lungs at static and relaxed conditions
* Measured by passing a pressure transducer/rubber ballon down the esophagus and have pt inhale at TLC. Then switch between relaxing muslces and holding lungs @ large volume measuring the airway pressure and intrapleural pressure. Each point makes the compliance curve
105
What is the tool used to meaure intrapleural presssure (Ppl)?
Esophageal Pressure Monitor-P(ES)
106
Explain Hystersis. Use the image below to explain
* Inflation and Deflation curves are not the same
* Due to no surfactant initial inflation is hard and has low compliance, while deflation has much more compliance
107
Explain what happens when there is No Hysteresis. Use the image below to explain.
* Steep slope; no hystersis more compliant b/c less pressure needed to increase tidal volume d/t saline
* Lung and intrapleural space both have saline which abolishes the fluid gas interactions that cause surface tension
108
In contrast to the air-filled lung, the saline-filled lung has an ↑C and no hysteresis. Why?
The saline removes the air-gas interface in the respiratory zone. Thus, surface tension forces were removed and the lung easier to inflate
109
What is the Surfactant?
* Complex mixture of proteins and lipids produced by type II alveolar cells
* Mixes with thin layer of fluid on alveoli
110
What is the role of surfactant?
* Decreases surface tension by reducing attraction between H2O molecules
* Stabilizes alveoli of different sizes
111
Explain Surface Tension forces
Lateral attraction of liquid molecules exerts a force within the plane of the surface causing the liquid surface to contract to its smallest possible surface
112
Explain surface tension and static pressure in a soap bubble (alveoli)
* Static pressure produced inside the soap bubble is a result of tension at the spherical surface of the bubble
113
What is static elastic recoil due to?
Elastic tissue and surface tension of alveoli
114
During inspiration, muscle force must overcome?
* T(S)=Surface Tension (want to decrease size)
* T(T)=Tissue Tension (elastic recoil)
115
Explain LaPlace's Law
The alveolus is essentially a 'sphere', thus we can apply LaPlace's Law to describe the pressure (P) within the sphere (alveolus) due to surface tension
116
What is the equation for LaPlace's Law
* P=4t/r
* P=pressure within the sphere
* T=surface tension
* r=radius of the sphere
117
What occurs to alvelolus 1 if surface tension T1=T2, and P1>P2? And explain if this is a good or bad outcome
* Alveolus 1 collapses as it empties into Alvelous 2 (small alveoli would empty into larger alveoli)
* This is BAD, b/c with a collapsed alveoli surface area decreases and gas exchange is imparied
118
List the Physiological Importance of Surfactant
* **Lowers surface tension** which reduces the muscular effort necessary to ventilate the lunggs (reduces the Work of breathing)
* **Helps stabilize the alveoli** and keep them from collapsing at end- expiration
* Helps keep alveoli "dry" (reduces the tendency of surface tension to suck fluid into the alveoli)
119
List the Consequences of Reduced Surfactant
* Stiff lungs; decreased compliance
* Atelectasis; alveolar collapse
* Edema
* Infant respiratory distress syndrome
120
How do the chest wall and lungs move during inspiration and expiration?
Move together; are in series with each other
121
What is the total respiratory system (PRS) equation and what does it calculate?
* **PRS=PL+PCW**
* Sum of pressures exerted by each component (lung & chest wall)
## Footnote
* PRS= Recoil pressure of total respiratory system
* PL=Pressure exerted by the lungs
* PCW=Pressure exerted by the chest wall
122
Below is a graph of the static relaxation pressure-volume curve of the respiratory system. Explain what is occuring in the lung and chest wall at points a and b.
a. Chest wall wants to expand (@FRC)
b. Lungs want to recoil (@FRC)
a&b are at opposite and equal forces=equilibrium
123
Below is a graph of the static relaxation pressure-volume curve of the respiratory system. Explain what is occuring in the lung and chest wall at points c and d.
c. High pressure causes chest wall expansion (
124
Below is a graph of the static relaxation pressure-volume curve of the respiratory system. Explain what is occuring in the lung and chest wall at points e,f and g.
e. Chest wall happy place. High volume=low pressure. Chest wall wants to expand out ~70% of TLC (>FRC: Inhalation)
f. High volume=low pressure in lung d/t elastic force (>FRC: Inhalation)
g. Highest lung volume both want to collapse
125
@FRC: Equilibrium positions
* Chest wall wants to expand out to ______ of TLC
* Lung wants to recoil in to ________ of TLC
* ~70%
* ~10% (i.e. minimum volume)
126
What diseases can alter Lung Compliance?
* Emphysema
* Fibrosis
* Edema
127
How does Emphysema alter lung compliance?
* It increase compliance, lung loses recoil
* Causes the loss of alveoli and elastic tissue
* Inflates and deflates very easily causing airways to collapse sooner
* Increases the slope of the V vs P curve
128
How does Fibrosis and Edema alter compliance?
* Fibrosis causes a decrease in surfactant
* Edema causes a stiff lung
* Both decrease compliance, makes air hard to get in the lungs and easy to get out
* Decreases the slope of the V vs P curve
129
What are the resistive properties of the lungs? and what causes them?
* **Tissue frictional R**-Due to tissue sliding over tissue
* **Airways (airflow) R**- Due to the friction of gas moving through the airways
130
What are the physical factors that determine resistance to airflow?
* Viscosity- ↑ viscosity, ↑ resistance and vice versa
* Length: ↑ length, ↑ resistance and vice versa
* Radius: ↑ radius, ↓ resistance (inversely related to resistance)
131
What is the equation that determines resistance to airflow?
* R=𝚫P/V-dot (cm H20/L/sec)
* R=Resistance
* 𝚫P= change in pressure
* V-dot=Volume of gas per unit time (rate)
132
List the factors influencing airway resistance
1. Autonomic control of smooth muscle
-Parasympathetic via vagus nerve
-Constriction via Acetylcholine
-Dilation via circulating Epinephrine
Bronchial smooth muscle also constricted by:
2. CO2
3. Airway irritant receptors via vagal reflex
133
Explain the functional importance of autonomic control of airway resistance
1. Provide reflex arc for airway constriction following inhalation of irritants (parasympathetic)
2. Provide airway dilation during excercise
-Decreased parasymphathetic influence
-Increased circulating epinephrine
134
What can cause airway constriction?
Decrease CO2 in alveoli
135
Using the graph below explain the changes in airway resistance with differing lung volumes
* At maximum Inspiration: ↑ airway radius= ↑ volume= ↓ resistance
* At maximum Expiration: ↓ airway radius=↓ volume=↑ resistance
136
Define Radial Traction
Each alveoli pulls on one another → resulting in pull on airway (keeping airway @ a specific radius)
137
What does airway diameter depend on in Lung Parenchyma
## Footnote
Parenchyma-portion of the lung involved in gas exchange
Retractile force of tissue surrounding airways
138
As lungs expand, what happens to retractile force on the airways?
It increases
139
What increases resistance on the airways?
Dynamic compression
140
What happens to intrapleural pressure during forced expiration?
* Intrapleural pressure becomes positive and compresses and may even collapse small airways
* Some air remains in the lungs, AKA residual volume
141
What is dynamic compression of the airways responsible for?
* Reason for residual volume (RV) in the normal lung
* Reason for increased RV with COPD
142
Which of the following will decrease the work of breathing?
a. Increase alveolar surface tension
b. Decrease compliance
c. Increase tissue tension
d. Increase compliance
d. Increase compliance
143
During inspiration, the lungs must work to overcome all of the following, except:
a. elastic recoil forces of the lung
b. Pulmonary resistance
c. airway resistance
d. chest wall resistance
d. chest wall resistance
144
Which of the following would occur after being stabbed in the left lung?
a. The right lung collapses and the left lung would be compressed during inspiration
b. Negative intrapleural pressure is lost and the right lung will be compressed durig inspiration
c. Positive intrapleural pressure is lost and the left lung will collapse
d. The left lung collapses and the right lung would be compressed during expiration
b. Negative intrapleural pressure is lost and the right lung will be compressed durig inspiration
145
Which of the following groupings are correct regarding air flow, airway zones, and the zones of highest resistance:
a. Bulk flow; Zones 0-16; Zone 5
b. Diffusion; Zone 0-16; Zone 18
c. Bulk flow; Zone 17-23; Zone 5
d. Diffusion; Zones 17-23; Zone 18
a. Bulk flow; Zones 0-16; Zone 5
146
Intrapleural pressure becomes more negative during:
a. Forced expiration
b. Normal expiration
c. Deep inspiration
d. Normal inspiration
c. Deep inspiration
-
Key Links
-
Subjects
-
Company
-
Find Us
-
