exam 2 lecture 15 and 16 Flashcards
gas flow or ventilation (L/min)
blood flow (ml/min) usually cardiac output
PIO
partial pressure of oxygen in inspired gas
alveolar gas flow/unit time or alveolar ventilation
PAO2
partial pressure of oxygen in alveolar gas
PaO2
partial pressure of oxygen in arterial gas
PaCO2
partial pressure of CO2 in arterial blood
a ventilator does what?
Create a positive pressure at the airway opening to push air into the lung
normal breathing is caused by ___ pressure
negative pressure within the lung to suck air in
air moves from low pressure to high pressure
true or false?
false
always high to low- down the gradient
PB
atmospheric pressure = Patm
PPL
plural space pressure
pressure of the bag around the lung
decrease in pressure (more negative)= inhale
diaphragm is innervated by the ___
phrenic nerve
what happens when the diaphragm contracts?
increases volume of the thorax
pulled down and pushes ribs out
External intercostal muscles aid in
inhalation (expand the thorax)
internal intercostal muscle aid in ___
expiration
quiet expiration is a ___process
passive (does not take energy)
___ muscles are accessory for inspiration and are recruited only during maximal inspiratory effort
scalene and sternocleidomastoid
abdominal muscles can be used for ___ if the lungs are stiff to ___
active exhalation
push the air out
lungs contain ___ making the lungs want to collapse ___
elastin
inward
the chest walls are springy and want to ___
recoil outward (expand)
what keeps the lung inflated and keeps the chest wall from pushing open?
negative pleural pressure
fluid in the pleural space does what?
allows the lungs and ribs to slide
keeps them stuck together (slides and water)
boyles law
P1V1=P2V2
volume and pressure are inversely related. as volume gets bigger pressure gets smaller (more negative) and vice versa
increase in volume =more negative pressure
by boyles law if you increase volume, what happens to pressure?
becomes more negative
more negative pressure within the alveolar causes ___
gas to flow into the alveoli (air goes high to low)
___ says pressure and volume are inverse to each other.
boyles law
as volume increases, pressure decreases
as volume decreases, pressure increases
PAW
airway pressure
PALV
alveolar pressure
PB
also PATM
atmospheric pressure= use 0 in most cases
PTP
transpulmonary pressure= pressure across the alveolar wall
PTP=PALV-PPL
transpulmonary pressure = alveolar pressure = pleural pressure
unit for pressure
cmH20
mmHg
the more negative your pleural pressure = ___ transpulmonary pressure
higher (bigger the difference between alveolar pressure and pleural pressure)
deep breathe, pleural pressure becomes ___
more negative
boyles law- increase in volume = decrease in pressure
when you relax and exhale, pleural pressure becomes ___
more positive
decrease in volume = increase in pressure
if you breathe in through coffee straw, pleural pressure will become extra ___
negative (have to pull really hard)
yellow arrows?
transpulmonary pressure:
= pressure across the alveolar wall
• PTP = PALV - PPL
pressure to keep alveolar open (wants to collapse this keeps them open)
blue arrows?
movement of air in or out of lungs
at peak inspiration what happens to Palv and Patm
equalized
when diaphragm relaxes, air is expelled passively from elastic recoil. What has happened to PPL?
increases (more positive)
decrease in volume= increase in pressure
pushed air out
negative PALV
air is being sucked into the lungs
PALV is positive =
air is being pushed out of the lungs
the harder it is to breathe in. what happens to PPL
becomes more negative- pulls in harder into the lungs
pneumothorax
loss of negative pleural pressure- air rushes into the pleural space when damage to ribs
what does this show?
pneumothorax
everything at zero. lung collapses, and ribs flare out
air does not move in or out of lungs
why is Ppl always slightly negative during normal breathing?
to keep lungs inflated and prevent ribs from flaring. hold everything together
when in the respiratory cycle is Ppl most negative?
peak inhale
what is PPL if you have an open chest wound?
0 same as the atmosphere. lung deflates, ribs expanded
How does a open chest wound affect breathing?
stops breathing, can’t change pressure, air wont go in or our of lung
how to know asthma medication working
asthma= small tube= needs bigger negative to inhale into lungs (-13)
meds= decrease in negative (more positive)= easier to get air into lungs (-8)
normal in and out breathing
tidal volume
total amount you can inhale
inspiratory capacity
total amount of air you can breathe out
expiratory reserve volume
total amount you can breathe in and out
vital capacity
amount of air left in your lungs after you exhale
residual volume
amount of extra air you can breathe in after tidal volume
inspiratory reserve volume
normal amount of air breathing in and out
tidal volume
total amount of air left in your lungs after breathing out normally
functional residual capacity
total amount of air you can breathe in and out and left in your lungs
total lung capacity
inspiratory reserve volume
vital capacity (biggest in and out)
tidal volume
normal breathing
functional residual capacity
amount left after regular breathing (shot in the head)
expiratory reserve volume
(biggest exhale possible)
residual volume
(dead space air that is always in the lungs)
what can’t spirometry measure?
residual volume
how to measure residual volume
plethysmography
___ is the volume of gas that can be contained within the maximally inflated lungs (average human = 6 L)
Total lung capacity (TLC)
___ is the volume of a single expired breath (10-20 ml/kg for animals; average human has 500 ml/breath)
Tidal volume (VT)
____is the maximal volume that can be expelled from the lungs after maximal inspiration (av. human = 4.5 L)
–Vital capacity (VC)
___ is the volume of gas that remains in the lungs after maximal expiration (av. human = 1.5 L)
Residual volume (RV)
–___ is the volume remaining in the lungs at the end of a normal tidal expiration (av. human = 3 L)
Functional residual capacity (FRC)
–If you just stop breathing at the end of a breath and relax (with an open glottis), your lungs will be at ___
functional residual capacity (FRC)
1.The lung tissue contains elastin, making the lung have a tendency to recoil ___________. The ribs are springy and recoil ___________.
in
out
The pleural space contains ____________. The pleural pressure is (almost) always ____________ in a normal animal.
fluid
negative
(keep lungs open)
When the diaphragm contracts, the thoracic volume becomes __________, and due to Boyle’s law, therefore the intrathoracic pressure becomes more _________________.
bigger
negative (smaller)
During inspiration, pleural pressure becomes more ______________, leading to the alveolar pressure becoming more _______________. Because atmospheric pressure is always constant, air moves ________ the alveolus and the alveolar pressure goes to _____________.
negative
negative
inward
equal=0
If the pleural pressure is -5 cmH2O at FRC, which of these is it likely to be at TLC? (a) -5 (b) 0 (c) -10 (d) +5
-10
more negative= TLC→ total lung capacity
FRC→ functional residual capacity (left after exhale)
TLC is bigger, increase in volume = decrease in pressure = more negative
During expiration, as the pleural pressure becomes less ___________, the alveolar pressure becomes _____________, causing air to __________ the lung.
negative
positive
leave (push out)
If the pleural pressure is -5 cmH2O at FRC, which of these is
it likely to be at RV? (a) -5 (b) 0 (c) -10 (d) +5
+5
pleural pressure has to be equal and opposite to residual volume to keep lung inflated
If you were paralyzed by a poison-tipped arrow, what would your lung volume be as you suffocated to death?
FRC functional residual capacity
If you breathe in as much as you can and then breathe out as far as you can, what volume have you exhaled?
What volume is left in your lungs?
vital capacity
residual volume
Why can you measure IRV with a spirometer but not FRC
can not measure residual volume therefore can not measure functional residual capacity
but can measure inspiratory reserve volume
When you are breathing normally, what lung volume is each breath (the name, not the number of mls)?
total volume
where do you start and finish
FRC (functional residual capacity)
TLC (total lung capacity)
why is there a gap?
hysteresis
easier to deflate then to inflate
hysteresis
easier to deflate then to inflate
gap in pressure volume curve
compliance
change in lung volume/change in pleural pressure
how stretchy are the lungs
why non linear?
stiffer as you start to get to TLC, compliance gets worse
ribs are in the way
what sort of animals might have greater lung compliance?
foul- younger stretchy rib cage
a chest bandage will have what effect on compliance
decreases- makes ribs less stretchy
change in volume/ change in pressure
compliance = how stretchy lungs are
loss of elastin is called ___ which will make compliance ___
emphysema
higher (lungs will not want to contract anymore- more holes= more stretchy)
elastin into scar tissue is ___ and causes compliance to ___
fibrosis
decrease
(not as stretchy- thick water balloon vs thin water balloon)
•The lung parenchyma is ___and will collapse if force is not applied to expand it
passive
•Elastin within alveolar walls contributes to passive ___ of the lungs
deflation
____ within the pulmonary interstitium resists further expansion at high lung volumes
•Collagen
•If elastin is reduced, compliance gets ___
higher
(make lungs more stretchy, less things trying to make it collapse)
which has the most compliance?
blue line, floppy balloon (emphysema)
what represents fibrosis
stiff balloon= less compliant
A saline filled lung has much greater compliance and a smaller hysteresis. Why? Saline abolishes ___
surface tension
The pressure required to maintain alveoli in the open state is related to the ___ (T) and radius (r).
surface tension
laplace law
pressure = (4 x surface tension)/radius
So small alveoli (small r) would collapse before big ones
harder to hold open tiny bubble then big bubble
true or false
laplace law says it is easier to hold open a small bubble then a big bubble
false
small bubble would collapse before big one
P=(4 x surface tension)/radius
____ is a phospholipid synthesized by Type II cells by lamellar inclusion bodies
pulmonary surfactant
pulmonary surfactant reduces ___
surface tension, reducing pressure needed to keep alveoli open
___ also allows surface tension to vary directly with radius, so it reduces the extra surface tension in smaller alveoli. So both small and large alveoli can exist
pulmonary Surfactant
what happens in lungs of premature baby?
no surfactant = increase in surface tension
= more negative pressure needed to open alveoli→ ventilator turned up high → can lead to bursting alveoli if pressure too high
•Alveolar walls and airway walls are structurally connected, and individual alveoli are prevented from isolated collapse by ___
“tethering“
tethering in alveoli
if an alveolus or airway begins to collapse, tension on the walls (exerted through collagen fibers) from neighboring alveoli tend to hold it open.
pulmonary edema will do what to compliance ?
decrease- make less stretchy/more stiff
emphysema will do what ___
increase compliance by a loss of elastic tissue
lungs don’t want to collapse as hard
loss of surfactant will do what to compliance?
decrease compliance (make less stretchy because it increases surface tension) (premature baby)
floppy rib cage will ___ compliance
increase (more stretchy)
chest bandage will do what to compliance?
decrease
(less stretchy)
pulmonary fibrosis (scar tissue)
decrease in compliance (less stretchy)
emphysema
loss elastin
more compliant (more stretchy) thin balloon
atelectasis
collapsed alveoli (baby not enough surfactant)
decrease compliance (increase surface tension)
alveoli collapse
atelectasis
baby no surfactant (decrease compliance -less stretchy- more stiff)
a fibrosis lung will have a lower TLC then an emphysema lung.
true or false?
true
fibrosis= less compliance = not as stretchy
An atelectic lung has ___compliance, and is therefore harder to ventilate and easier to damage with high ventilator settings
lower
(less stretchy/more stiff)
-What happens to lung compliance under anesthesia in the control group?
control = ZEEP= green
compliance decreases= harder to ventilate as the procedure continues
true or false
emphysema will have smaller residual volume then fibrosis
false
emphysema= more compliant= big holes= more dead space= more RV left in the lung
true or false pulmonary fibrosis will have a smaller TLC then a normal lung
true
not as stretchy= decreased complaince= smaller total lung capacity
what do you think the lung volumes will be in a patient with atelectasis?
decreased RV?- collapsed alveoli= less dead space
???
•For a particular lung/chest wall, at a specific pressure, the volume will ___, whether that pressure is generate by a change in PPL or by positive pressure ventilation (a ventilator)
be the same
•Static ___ is measured during a pause in respiration, while there is no airflow
compliance
= ∆V/∆P
complaince
how to graph compliance
pressure-volume curve
A smoker develops emphysema. When they take a deep breath, their lungs expand from an FRC of 800ml with a pleural pressure of -4cmH2O to a TLC of 2500 ml and a PPL of -8cmH2O. What is their static compliance?
change in volume/change in pressure
(2500-800)/(8-4)
1700/4
425
A smoker develops emphysema. When they take a deep breath, their lungs
expand from an FRC of 800ml with a pleural pressure of -4cmH2O to a TLC of 2500 ml and a PPL of -8cmH2O.
Draw a pressure-volume curve illustrating your answer. Label the axes with numbers and show your work.
if emphysema has worsened. would compliance be higher or lower?
higher/steeper
more complaint
P-V curve expiration and inspiration
What is the ΔPPL needed to reach TLC in the baby, before and after the surfactant (qualitative answer)?
before surfactant= decrease in compliance= harder to breathe in= greater change in Ppl needed
after surfactant = increased compliance
Why might generating very high ΔPPL for several days be a
difficult for a baby?
alveoli would burst, babies are less musculature and would get tired from the increased effort
Draw a P-V curve for a patient with a bilateral pneumothorax
dot
can not breathe in or out
no change in pressure or change in volume
compliance after tight chest bandage
bandage= less compliant= stiff
why are the alveoli at the top of the lung bigger?
gravity
what is this showing?
at increased pressure all alveoli are open
at decrease pressure alveoli on the bottom are closed due to gravity
Because of gravity and the weight of the lung, the pleural pressure is ___ at the base than at the apex
less negative
regional difference of compliance and ventilation at FRC
base: higher compliance because alveoli are open but have lots of room
regional difference of compliance and ventilation at FRC
apex= compliance drops because alveoli are almost full
(balloon fully blown up- any bigger would explode)
When you forcefully exhale all the way to RV, the pressure at the base actually ____ airway (atmospheric) pressure. As a consequence, airways collapse and no gas enters with small inspirations (diaphragm movements)
exceeds (becomes +)
at RV, the base of the lung will have ___ compliance compared to the top of the lung
decreased (base of lung goes to +, alveoli smooshed closed→ harder to inflate)
where at the apex of the lung- compliance would be better because alveoli have some air but lots of room before they reach TLC
___= change in pressure/flow
resistance
units for resistance
change in pressure/flow
cmH20/L/s
resistance is dependent on ___
- Laminar versus turbulent flow
- Radius of tube (narrow airway)
- Length of tube (short straw vs. long straw)
- Lung volume (tethering)
Viscosity of gas/liquid (divers breathe helium
in conducting airways, gas move by ___
laminar flow (150ml)
in the respiratory zone, air moves by ___
diffusion because the volume is so much bigger (150 compared to 3000ml)
what happens to the area of airways
respiratory zone has drastic increase in SA→ air moves by diffusion instead of laminar flow
why is flow faster in the upper airways?
need to keep up with the respiratory airways. a bunch of lanes merging into one, needed to go faster to keep up
•In the lungs, thousands and thousand of bronchioles merging into the larger bronchi and trachea – the flow rate of air must get faster with every merge
ohm’s law
R= change in pressure/change in flow
where is most of the resistance in airways?
upper airway (nasal passages, larynx, trachea, large bronchi)
in healthy animal only 20% of resistance airways are in the small airways
ohms law
change in pressure/ flow
hagen-poiseuille equation
The Hagen–Poiseuille equation is a physical law that gives the pressure drop in a fluid flowing through a long cylindrical pipe.
- the flow rate of the gas (airflow, here)
- the length of the pipe
- the dynamic viscosity of the fluid
- especially the radius of the tube (r4; radius to the fourth power!)
based on hagen poiseuille equation what effects resistance the most?
radius
•How do we decrease our airway resistance during exercise?
increase radius (poiseuille’s equation R=1/r4
make glottic cleft larger
what happens to resistance when radius goes from 1 to 0.5?
increases by 16 times!
During an asthma attack, the smooth muscles of the small airways constrict (___) and get plugged with mucus and pus.
bronchoconstriction
•Small terminal airways have the highest ___resistance
individual
- but total resistance for all these airways together is less than that of the medium sized airways, because resistances in parallel sum as reciprocals (like electricity)
- The greatest resistance is actually in airway generations >2mm diameter
•The greatest resistance is actually in airway ___ diameter
generations >2mm
Smaller airways do not have cartilaginous support, and are easily distended or compressed as the lungs inflate and deflate. As lungs inflate, the smaller airways dilate from radial traction from the alveoli, which ___ resistance during inspiration
reduces
Bulk air flow may be turbulent or laminar depending on velocity, airway diameter and airway branching. ___ has less resistance; where flow becomes ___ there is greater resistance.
Laminar flow
turbulent
how to measure change in pleural pressure
esophageal balloon
•We measure pleural pressure (PPL) with an esophageal balloon (cmH2O)
•We measure ___with a pneumotachnograph attached to a mask (L/s)
airflow ( V (dot) )
where is inspiration?
would you give oral or nebulisation?
oral
want resistance to decrease= want it easier to breathe
You are examining a horse with asthma. You place an esophageal balloon and a pneumotachnograph. What does each of these measure? Units?
pleural pressure
cmH20
During tidal breathing, the PPL measurements vacillate from -5cmH2O to -35cmH2O.
Which of these pressure values is associated with maximum inspiration?
-35
more negative= inhale
During tidal breathing, the PPL measurements vacillate from -5cmH2O to -35cmH2O.
If the flow rate during tidal breathing is 10 L/s, what is his pulmonary resistance (RL)?
R= change in pressure/ change in flow
(35-5)/(10)
3.5 cmH20/L/s
You administer atropine, and the RL changes from 3.5 to 1 cmH2O/L/s. Which component of resistance do you think it affected?
increased flow rate
or
change in pressure
Poiseuille equation: things that effect resistance: the flow rate of the gas (airflow, here) • the length of the pipe • the dynamic viscosity of the fluid • especially the radius of the tube (r4; radius to the fourth power!)
You see a racehorse for laryngeal hemiplegia. The left arytenoid shows minimal abduction during exercising endoscopy. If you do a tie-back surgery and increase its laryngeal aperture radius from 5cm to 10cm, what effect will that have on resistance, quantitatively?
decrease resistance by a factor of 16
Poiseuille Equation
R= 1/radius4
What other factors beyond radius affect resistance?
the flow rate of the gas (airflow, here)
- the length of the pipe
- the dynamic viscosity of the fluid
- radius of the tube (r4; radius to the fourth power!)
Hagen–Poiseuille equation
if you measured the max change in Ppl in this racehorse during max exercise before and after the tie back, what difference would you expect to see?
change in PPl would decrease, less effort to breathe → less pleural pressure = less negative
this westie has a very low TLC. his lung compliance is very low. what disease does he have?
pulmonary fibrosis (very stiff lung)
The Pekinese has a slightly increased TLC but a huge RV. His lung
compliance is very high. What disease does he have?
emphysema
no elastin- floppy lungs- too stretchy
The bulldog has incredibly high airway resistance (R What is the root cause? What would happen to his resistance if he was intubated?
upper airway resistance
brachiocephalic upper airway
intubation would make it better.
what happens if you intubate pulmonary fibrosis paitent?
nothing, issue with alveoli, tube in throat will not help
___ is how hard to move air through a tube
resistance
___ is how stretchy/elastic is the lung
compliance
change in volume is inverse to change in pressure
boyles law
pressure volume curves measure what
compliance
change in pressure/ change in flow
ohm’s law
what disease change resistance in lower airways
asthma
decrease in radius of the bronchioles will increase resistance by factor of 16
flow volume loops for asthma and emphysema
harder to expire
I n animals that have a pulmonary obstructive disease (obstruction in the lung, not the upper airway), air from the large airways can be expired without problems so at the beginning of the expiration, flow is normal.
With asthma, the small airways are narrowed so in the last part of expiration the air will come out slower (you can simulate this by blowing out through a straw), shown by the flattening of the curve. Likewise, with emphysema, gas is trapped in the huge pockets and therefor it can’t be exhaled (“gas trapping”, high residual volume)
Flow-volume: loop is concave, FVC normal, expiration is harder
flow volume loop for fibrosis
Restrictive lung disease means that the lungs can’t expand, either due to scar tissue in the parenchyma (fibrosis) or an extrathoracic restriction (a tight chest bandage), so the total lung capacity (TLC) is low. Although an accurate diagnoses of total lung volume is not possible with spirometry (residual lung volume cannot be measured with a spirometer) flow-volume results can be very suggestive for a restrictive lung disease. Total lung volume is low, which results in a low (forced)VC.
Flow-volume loop: shape normal, FVC low, inspiration is harder
