Exam 3 Flashcards
How to solve for the concentration of a gas? Using partial pressure and total pressure
The fractional concentration of the gas = Partial pressure of the gas / total pressure of all gases
Example: Oxygen
149.0 / 713 = 0.21. <—— humidified gas! Taking humidity / displacement into account
159.0 / 760 = 0.21 <——- This is dry air!
FOR OUR CLASS:
149 / 760 = 0.196 <—— the 760 is what we will use for our class!
^713 would give us numbers that line up but for our class we use 760 as the total pressure
This is just rearranging: PIO2 = FIO2 (Pb - PH20)
Please watch lecture 3/6 13:10 for clarity
For our class, we are always going to use _____ mmHg for the total pressure when trying to find the concentration of a gas in the lungs!
760 mmHg!
How to figure out the concentration of nitrogen in lung air
569 / 760 =0.749 –> 74.9%
If we look at air in the lung right now, it should have a nitrogen concentration of about 75% if we take into account humidity being a portion of total air
Normal end tidal CO2
40 mmHg
For the Fowler’s test: On inspiration, air that’s in the anatomical dead space should have ____% nitrogen in it. Why?
0%
because there wasn’t any nitrogen in the inspired source.
The Fowler’s test is a cheap easy way to find out..
how much anatomical dead space someone has.
In the Nitrogen washout test, The greatest reduction in nitrogen concentration will be on the _____ breath. Why?
The greatest reduction in nitrogen concentration will be on the first breath because that is when there is the most nitrogen in the lungs to be displaced / diluted.
The Nitrogen Washout test is halted when the patient is expiring nitrogen at a concentration of _____
~2.5%
Typically, an abnormal Nitrogen Washout result is if it takes greater than __ minutes for nitrogen concentrations to get to ___%
-7 minutes
-2.5%
However, in a healthy person is should only take about 3.5 minutes!
Therefore, 7 minutes is abnormally abnormal because its really 2x what “normal” is in a healthy adult
The peak expiratory flow rate would be kind of the product of these two things:
-Elastic recoil pressure (being high)
-Pleural pressure (being positive to push air out)
The elastic recoil pressure in a healthy lung at total lung capacity, is about ___ cmH20
+30 cmH2O
The combination of the constriction of these two accessory muslces will give us a positive pleural pressure during forced expiration
-abdominal constriction
-internal intercostal constriction
The combined action of abdominal constriction and internal intercostal constriction should give us a pretty positive pleural pressure.
If you have a beaker of solution and it is surrounded by an environment of oxygen and you give it time to equilibrate, will the enviornmental or solution’s PO2 be higher?
They will be equal!
Oxygen is not very soluble, so we’re not going to have a great quantity of oxygen in solution→However, we should have about the same PO2 in the solution as what we have in the environment→Again, assuming we give the beaker of solution a long enough period of time to equilibrate with what’s in the environment.
The solubility of oxygen per dL in aqueous solution is ____
0.003 mL O2 / mmHg PO2
This means that for each mmHg I have, i can push 0.003 mL of oxygen into solution!
The solubility of oxygen per mL in aqueous solution is ____
0.00003 mL O2/ mmHg PO2
How much oxygen is dissolved in a solution with a PO2 of 100 mmHg?
How much = quantity of gas → will always be a volume!
100 x 0.003 =0.3 mL of O2 / dL of blood
How did we get those numbers?
The 100 mmHg is our PaO2
The 0.003 is our solubility of oxygen
Normal PvO2
40 mmHg
Normal PaO2
100 mmHg
How much oxygen is dissolved in a solution with a PO2 of 40 mmHg?
40 x 0.003 = 0.12 mL O2 / dL of blood
How did we get those numbers?
The 40 mmHg is our PvO2
The 0.003 is our solubility of oxygen
When you are trying to figure out how much oxygen is dissolved in solution, you have to know two things:
- PO2 of the solution
- The solubility coefficient
The solubility coefficient never changes!
If we have a solution and we want to figure out how much dissolved oxygen we have, we just multiply the ___ times the ______
PO2 x solubility coefficient
Each deciliter of blood has __ of O2 dissolved in it.
0.3 mLs
We need about ___ mLs of O2 each minute to stay alive
250
Each gram of hemoglobin we have stores/carries ___ mL O2
1.34 mL of O2
1.34 mL O2 / gram Hb
If you have a blood sample with a Hb of 15 g/dL. How much oxygen is that amount of Hb capable of carrying?
15 x 1.34 =20.1 mL O2 / dL of blood
This gives us our oxygen carrying capacity of Hb!
We got it by doing:
Amount of Hb x carrying capacity of 1 g of Hb
Amount of Hb: 15 g / dL
Carrying capacity per g of Hb: 1.34 mL O2 / gram of Hb
This gives us the total amount of oxygen that can be carried! We can not carrying more than 20.1 mL of O2 unless we have more Hb in the sample
The oxygen content of arterial blood is about
20.1 (or 20) mL O2/ dL of blood
If we had a Hb of 15 g/dL with a sat of 100%, how many mL of O2 would we have in that sample?
What if our Hb sat was 10%?
100%: 20.1 mL of O2 / dL
10%: ~2 mL of O2 / dL
The two factors you need to figure out how much oxygen is on hemoglobin:
-Carrying capacity of Hb (So you have to know how much each gram of hemoglobin can carry and how much hemoglobin we have in the sample.)
-Hb oxygen saturation number
For our class, we’re going to say that a normal hemoglobin is _____ grams/dL in average healthy adult patients.
15 g / dL
Men have more, women have less
Adult Hb has 2 __ subunits and 2 ___ subunits
2 alpha, 2 beta
Fetal Hb has 2 __ subunits and 2 ___ subunits
2 alpha, 2 gamma
Adult and fetal Hb are tetramers, what does this mean?
They have four component parts! A total of four subunits.
How many O2 molecules can each Hb subunit carry?
How many O2 molecules can Hb carry total?
Each subunit can carry 1 molecule
1 Hb molecule can carry 4 O2 molecules total
Why are some of our muscles bright red?
Myoglobin!!
Red muscles are red because they have lots of iron in them and the iron is in the form of myoglobin
What two things do you add to find out your oxygen content?
Oxygen Content = Bound oxygen + Dissolved Oxygen
20.1 + 0.3 mL =20.4 mL –> oxygen content
If we had a PO2 of 100, a normal amount of hemoglobin, and that hemoglobin was 100% saturated, our oxygen content in that sample would be 20.4 mLs of O2.
2 problems with carbon monoxide and Hb
- CO decreases the carrying capacity of Hb
- CO increases Hb affinity for oxygen
-Any hemoglobin that has just one carbon monoxide molecule stuck to it increases the affinity of that hemoglobin for the other oxygen binding sites.
-If you have one carbon monoxide stuck onto those four binding sites, EVEN if you’re carrying three O2 molecules, that hemoglobin might not want to release those O2 molecules
-This is bad bc it prevents a lot of the oxygen from unloading.
In general, we could say just (for now) that venous hemoglobin is probably only about ___ saturated.
Lecture 3/25
75%
3/4 saturated!
-From our Fick equation numbers: we said that arterial blood had about 20 mL of O2 and venous blood had about 15 mL of O2.
-This would probably imply that about a quarter (25% or ¼ of 20 ml is 5 mls) of the oxygen that was carried by hemoglobin has fallen off.
-If a quarter falls off, then 75% would still remain.
Arterial saturation %
100%
Oxygen content of veins using Hb saturation
20.1 mL O2 / dL x 75% saturation = 15.08 mL O2/dL of blood
-We multiply the 75% times the carrying capacity of 20.1 ml O2, and we get the amount of oxygen actually there which the book comes up with 15.08.
-For our class, to make things easy, we can estimate that as about 15.
**It holds up that ~97% of all circulation beds follow this pattern. **
Hb entering the coronary circulation is ___% saturated.
Hb exiting the coronary circulation via the coronary sinus is ___% saturated
-100%
-25%
The heart is set up to extract about __% of the oxygen that gets funneled through the coronaries.
75
Normal circulatory beds are about _% saturated in the venous blood with the exception of ____
- 75%
- the coronary’s arteries of the heart.
The lungs have a temperature of ____
37° C
Normal P50 value in a healthy hemoglobin
26.5 mmHg
3 forms of CO2 we are concerned with an their percentages
-Carbamino → 5%
-Dissolved CO2 → 5%
-HCO3- → 90%
Solubility of CO2
0.06 mL of CO2 / mmHg CO2 / dL of blood
If we have 1 mmHg pressure, we would have 0.06 mls of CO2
How many mls of CO2 dissolved in a normal dL of arterial blood? Show how you got that
40 X 0.06 = 2.4 mls of CO2 in a normal dL of arterial blood
Solubility x PCO2
-For arterial blood, we should have a PCO2 of 40
-So if we do 40 X 0.06 = 2.4 mls of CO2 in a normal dL of arterial blood
-For our class, we are going to say this is how we calculate the amount of dissolved CO2 in both arterial and venous samples
-The only thing that would be different would be what the PCO2 is of the sample
-So 40 in arterial blood, 45 in venous
-We are going to say that this makes up 5% of the total amount of CO2 in solution
How many mLs of CO2 are in the form of carbamino compounds?
2.4 mLs
How to find the total CO2 content using the dissolved CO2
You know dissolved CO2 makes up 5% of the CO2 content so…
2.4 mL x 20 = 48 mL of CO2 TOTAL
Why did we multiply by 20?
5% x 20 = 100% so just multiply the mL of dissolved CO2 by 20!
Looking at all the CO2 in all of its forms should be about 48 mLs of CO2 in one deciliter of blood.
How many mL of CO2 in a dL of blood are in the form of bicarb?
43.2 mL
48 mL total - dissolved (2.4) - carbamino compounds (2.4 mL) =43.2 mL
The CO2 content of venous blood should be about ___ mLs of CO2 per deciliter of blood.
52.5
-If we have a PCO2 of 45 in a 70% saturated oxyhemoglobin sample, we should have a CO2 content of about 52.5
Hemoglobin can do three things:
- It can bind or release oxygen.
- It can form carbamino compounds
- It can also buffer protons.
In obstructive diseases, is the VC high or low compared to normal?
low
In restrictive diseases, is the VC high or low compared to normal?
low
In restrictive diseases, is the RV high or low compared to normal?
low
In obstructive diseases, is the RV high or low compared to normal?
high
What is the alveolar pressure?
+35!
35 (PAP) = 25 (PIP) + 10 (PER)
What is an example of something that causes fixed (intra- or extrathoracic) obstruction?
ETT!
Both the expiratory and inspiratory flow volume loops are impacted
What is an example of something that causes variable extrathoracic obstruction?
Paralyzed vocal cords or part of the trachea removed/replaced
-Impacts inspiration
What is an example of something that causes variable intrathoracic obstruction?
Emphysema / asthma
Impacts expiration
Under healthy conditions we should be able to move ____% of our vital capacity out of the lungs within a period of one second during maximal forced expiration
80%
if its lower, theres a problem
With forced vital capacity, it usually takes about ___ seconds to get down to RV
8 seconds
FEV1 / FVC ratio
If my FEV1 is 3.6 L and my FVC is 4.5 L, what is the ratio?
3.6 / 4.5 =0.8 –> 80%
This is a normal FEV1 / FVC ratio
True or false: The FEV1 / FVC ratio in restrictive lung disease may be normal / high normal
TRUE!
Steps for PFT
- FEV1/FVC >70%?
- FVC
- TLC & RV (using hemodilution)
- DLCO (CO diffusion test)
- FEV1 reversibility with BD
For the closing capacity test, why does phase IV increase?
Alveoli at bottom of lung collapse (which were diluted with 80% O2 so less N2) and the air starts coming from the apex (nitrogen is less diluted, only 70%)
This is known as closing volume!!!
Phases of closing capacity test
- Anatomical dead space
- Transitional phase (same as fowlers)
- Plateau phase
- Closing volume
If phase 4 happens early in the closing capacity test, is this a good thing or bad thing?
Bad thing!
Asthma, emphysema (?)
Airways are thinner, not as much traction, small airways at base collapse early
True or false: RV increases as we get older
true
bc they lose elastic tissue as a function of age
Around what age do we have small airways collapse on pretty much every breath?
55
When does Adult Hb in a healthy person reach 100% saturation?
PO2 = 100 mmHg
When does fetal Hb in a healthy person reach 100% saturation?
PO2 = ~30 mmHg
What is the name of 2-3 BPG?
Acidic name?
2-3 DPG?
- 2,3 Bisphosphoglycerate
- Bisphosphoglyceric acid
- Diphosphoglycerate
Why do the lungs have a left shift on the oxyhemoglobin dissociation curve?
Less CO2 in lung air compared to pulmonary aterial blood PCO2
When comparing arterial and venous oxyhemoglobin curves, which one is shifted left? Why?
Arterial has a left shift bc it has less CO2 (and protons) compared to veins
CO2 combines with water to form
Carbonic acid
Carbonic acid dissociates into protons and bicarbs
Percentages of CO2 forms in venous blood
Dissolved –> 10%
HCO3- –> 60%
Carbamino –> 30%
Everything but bicarb form increases
When comparing arterial and venous Carbon dioxide curves, which one is shifted left? Why?
Venous! More room for CO2 becayse the hemoglobin is less saturated with oxygen
What oxyhemoglobin saturation % does schmidt want us to use for his class?
70%
For each dL of blood that passes through the lungs, we should have about ____ ml of CO2 unloading.
Show how you got this
4.5 mL of CO2
The arterial sample had 48 mls of CO2 in it; the venous sample has 52.5 mls of CO2 in it
52.5 - 48 = 4.5 mL
Explain the Haldane effect
- The fact that deoxygenated blood has more room to transport CO2 is sometimes called the Haldane effect
- The amount of CO2 transport we can have is dependent on oxyhemoglobin saturation levels
Most notable buffer for protons in an RBC
Hemoglobin!
Which is a weaker acid: deoxyhemoglobin or oxyhemoglobin
deoxyhemoglobin is a weaker acid than oxyhemoglobin
If it’s more prone to accepting a proton, it’s probably a weaker acid → Strong acids want to donate protons!
How long does it take for gas exchange to happen in our pulmonary capillaries, under normal conditions?
0.25 seconds
it takes a quarter of a second
What is the duration of time blood hangs out in the pulmonary capillaries, under resting conditions?
0.75 seconds
Under extreme circumstances, our cardiac output can pick up to the point where our blood is moving through the capillaries fast and is only spending ___ seconds in the pulmonary capillaries
- 0.25 seconds
If everything is working, this should not be a problem
-However, if we have bad lungs or if we have fluid in the lungs, so if we have something wrong with our ability to exchange gas, it might take a little bit longer.
-We might not realize that we have a diffusion problem until we pick up our level of activity and basically generate that problem because of the high cardiac output.
Why does equilibration of N2O happen quickly, in less than 1/4 of a second?
- The reason for that is nitrous doesn’t really have a ton of places to go in blood and it’s fairly insoluble.
- If I compare nitrous to oxygen, nitrous is a little bit less soluble than oxygen.
Nitrous is ___ soluble than nitrogen, but it’s definitely not ____ soluble than oxygen.
- More
- More
Nitrous is more soluble than nitrogen, but it’s definitely not more soluble than oxygen.
Carbon monoxide is sometimes used as a diagnostic gas to look at the ____ capabilities of the lungs.
why?
- diffusion
- The reason why they’re using this in a pulmonary function lab is that the diffusion of carbon monoxide is very similar to the diffusion of oxygen.
- You can measure how fast someone takes up carbon monoxide → if you give them a reasonable dose, the absorption of that carbon monoxide should pretty much mirror the absorption of oxygen.
-The faster we can pick up carbon monoxide, probably the better diffusion we have available to us.
-If carbon monoxide gets absorbed very slowly, then we probably have a problem with gas diffusion in our lungs.
f you want to find out if your kids smoke, probably do a blood test and look for _______ because it shouldn’t be there unless they’re working on machinery or working on the drive-through or something.
carboxyhemoglobin
With a normal situation, the blood spends about ____ times as long as what’s really necessary in the capillary to do the gas exchange – That makes up a safety factor.
three
Under normal circumstances, oxygen diffusion is a _____ limited compound.
perfusion
Therefore, we would say that CO in this case would be a _____ limited gas, which is what makes it useful for testing the ____ capacity of the lungs.
diffusion
diffusion
CO2 is ___x more soluble than O2
24
The diffusivity of CO2 is about __x that of O2
20
Diffusivity takes into account two things:
solubility and the square root of the MW of the gas
A normal V/Q ratio is around…
How did you get this?
0.80 or 0.85 are good numbers for our class (80 or 85)
How?
V/Q = 4200/5000 –> 0.84
V –> alveolar ventilation –> 4200 mL of air
Q –> Perfusion / CO –> 5000 mL of blood / min
If you have a shunt, the V/Q ratio will be…
Smaller!
If you have alveolar dead space, the V/Q ratio will be…
Higher than normal
Upper limit is infinity
in the circumstances of no blood flow but ventilation, the V/Q ratio can be as high as ∞
If we have absolutely no ventilation but we have perfusion, the V/Q ratio should be __
0
0/5000 –> 0
Which has a higher V/Q ratio - top or bottom of lung?
Top!
O2 would be high, CO2 would be low - compared to base
LaPlace’s law
LaPlace’s law basically says that air is going to go from smaller spheres to larger spheres (provided the larger spheres aren’t completely full to 100%).
Under healthy conditions, Laplace’s prediction doesn’t hold up; why?
Surfactant!
A small, less full alveoli with less surface area, will have more or less surfactant compared to a more full alveoli?
MORE!
The affected biological concentration of surfactant is going to be a lot higher in the smaller, less full alveolus
Anatomical dead space calculation
1 ml / lb of IDBW
Mixed expired oxygen (PEO2) at standard barometric pressure
120 mmHg
Mixed expired CO2 (PECO2) at standard barometric pressure
28 mmHg
Mixed expired N2 (PEN2) at standard barometric pressure
566 mmHg
Mixed expired water (PEH2O) at standard barometric pressure
47 mmHg
The big idea here is that if we have dead space developing in the lungs, our mixed expired air is going to have a _____ than expected PCO2
Lower
Normal pulmonary compliance
How did you get it?
0.2 L / cmH2O
Compliance is: △V/△P
△V would be 0.5 L
→ 500 mL VT
△P would be 2.5 cm H2O
-5 cmH2O at FRC→ -7.5 cm H2O at end inspiration → 2.5 cmH2O change
Plug it in like this: 0.5 L/2.5 cmH2O = 0.2 L/cmH2O
How many mL of O2 do we have in the lungs, at rest, in between breaths?
Show how you got it :)
395 mL of oxygen
thx avery for the pic im not writing it out
How much O2, in mL, do we use each minute?
250 mL
How long can we hold our breath? Why?
A little under 2 minutes
Because we have 395 mL of O2 in the lungs at FRC and we consume 250 mL / min of O2 –> 1.58 minutes
How many lobes in the right lung?
3
right lung is larger, has more volume, and is heavier c/t the left lung
Which lung is taller?
Left lung, even though it is smaller
How many fissures does the right lung have?
The left?
Right –> 2
Left –> 1
How many bronchopulmonary segments in the right lung?
Left?
Right –> 10
Left –> 8
Which side of the diaphragm is lower?
The left side of the diaphragm
REMEMBER the left lung is still taller!!!
Attachment points for scalene muscles?
Transverse process of cervical vertebrae and 1st/2nd ribs
Attachment points for sternocleidomastoid muscles?
Mastoid process and midline at the sternum
When I contract my external intercostal muscles it brings the thorax ____ and helps with _____
Anterior/forward
Inspiration
When I contract my internal intercostal muscles it brings the thorax ____ and helps with _____
-Closer to midline (Compress the thorax)
-Forced Expiration
Nose functions
-Heat and humidify air
-Act as a filter
-Smell sensors
What % of air is breathed in via the nose?
via the mouth?
50% for both
The top two turbinates/conchae on either side of the nose are projections of the ____ bone
ethmoid bone
The inferior concha is a projection of the ____ bone
maxillary
Which nerve takes care of our epiglottis?
Vagus nerve
Name the CN:
V
VII
IX
X
V - Trigeminal nerve (5)
VII - Facial nerve (7)
IX- Glossopharyngeal nerve (9)
X - Vagus Nerve (10)
The _____ nerve takes care of basic touch sensation or irritant sensation for the back ⅓ of the tongue
glossopharyngeal
In terms of pressure/pain/tickle/itch sensation on the front anterior ⅔ of the tongue are taken care of by the ___ nerve
trigeminal (V3)
Mandibular division of trigeminal nerve
The back ⅓ taste sensation is taken care of via the _____ nerve
glossopharyngeal
The _____ nerve takes care of taste sensation for the front/anterior ⅔ of the tongue
Facial
From Birth to 10 years of age, the narrowest part of the upper airway is the _____ ____
Cricoid cartilage
The most narrow point of an adult airway should be the ____ ___
transglottic space
