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Pulmonary Physiology part 2 [Gas Exchange]
Wacker 2/28 & 3/1 lecture - 2.5 hrs (starts with 2nd note packet)
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Physiology
02/23/2011

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Term
Dalton's law
Definition
total pressure of a mixture of gasses is the sum of the pressures of individual gases (sum of the partial pressures)
Term
atmosphermic pressure * % O2

at sea level this would be 760mmHg * 21% (0.21) = 160 mmHg

In a person with 100% oxygen this would be 760 * 1 = 760 mmHg

fun facts: CO2 = 0.3%, Nitrogen is 76-78%
Definition
partial pressure of O2 in the air (equation)
Term
the partial pressure of that gas in equilibrium with that liquid
Definition
According to Henry's law, at constant temperature the amount of a given gas dissolvd in a given type and volume of liquid is directly proportional to what?
Term
Henry's law O2 dissolved = solubility * PO2
Definition
the concentration of O2 dissolved in water is proportional to the PO2 in gas phase is an example of what law? how do you calculate the O2 dissolved?
Term
less, O2's solubility sucks it is 27 times less than CO2
Definition
the solubility of oxygen is greater than or less than CO2?
Term
DO NOT! solubility is different for different gases!!!!
Definition
equal partial pressure (do/do not) mean equal concentration
Term
3 ml O2/liter blood
Definition
what is the solubility of O2 in plasma?
Term
1) dry atmospheric air is humidified (reducing partial presure of O2)
2) CO2 diffuses from the pulmonary blood into the alveoli(reducing partial pressure of O2)
3) alveolar air is only partially replenished every breath with atmospheric air
4) oxygen is constantly absorbed into the pulmonary blood from the alveoli
Definition
Why is the partial pressure in the alveoli not equal to the atmostpheric partial pressure of oxygen?
Term
atmospheric: 160mmHg (760 * .21) alveolar: 100mmHg FiO2 *(Patm -PH20) -(PaCO2/RQ) .21 *(760-47)-(~40/0.8) = ~100
Definition
what is atmospheric PO2? alveolar?
Term
fraction of inspired oxygen
Definition
What does FiO2 stand for?
Term
respiratory quotient, ratio of total CO2 production to O2 consumption, typically around 0.8 (or you can multiply by 1.25 to make it easier)
Definition
what is RQ?
Term
carbs = 1.0, lipids = 0.7, proteins = 0.8, normally people are burning a combination of lipids and carbs
Definition
why is respiratory quotient usually 0.8?
Term
PAO2 decreases
Definition
what does increasing alveolar partial pressure of CO2 do to PAO2?
Term
high to low
Definition
gases move from __ concentration to ___ concentration
Term
A-a gradient
Definition
ideally, alveolar PO2 should equal arterial PO2, when compared what is this known as?
Term
high altitude, asthma
Definition
what factors can decrease alveolar PO2?
Term
pressure, surface area, diffusion coefficient, membrane thickness, membran resistance

all part of Fick's law of diffusion
Definition
what things can alter diffusion rate?
Term
diffusion rate is proportional to:

(change in pressure * SA * diff. coefficient)/(membrane thicknes * membrane resistance)
Definition
what is Fick's law of diffusion?
Term
COPD/emphysema decreases surface area
Pulmonary Edema increases membrane thickness(diffusion distance)
Pulmonary fibrosis increases membrane thickness
Definition
how does COPD or emphysema decrease diffusion? Pulmonary edema? Pulmonary fibrosis?
Term
1/3 = normal
1/2 = with diffusion problem

there is plenty of time for O2 to diffuse at rest in either state

diffusion is not a limiting factor
Definition
At REST typically at what distance along the capillary is all of the oxygen diffused from the alveoli? with a diffusion problem?
Term
normal: about 75% of the way
diseased: can go the whole length of the capillary without full diffusion

diffusion is limiting in the diseased state during excercise as there is not enough time for the oxygen to diffuse where it needs to.
Definition
with EXCERCISE(say 3 x cardiac output) how far down the capillary is all of the O2 diffused normally? with a diffusion problem?
Term
normal: about 1/3
Definition
how far down the capillary does it take CO2 to diffuse in a normal person?
Term
there is a lower change in pressure (delta P) basically the CO2 goes from 46 to 40mmHg and the O2 is going from 40 to 100mmHg
Definition
if CO2 is more soluble that oxygen, why does it take about the same amount of time for it to diffuse?
Term
basically, what causes the A-a gradient?


most causes of hypoxia (except for hypoventilation)
Definition
why doesn't PAO2 = PaO2?
Term
altitude will change PO2 overall (decreases both alveolar and arterial equally, so no A-a change)

hypoventilation does not change A-a

increased thickness of lungs allows the alveoli to become ventilated (increased Palv) while the arterial PO2 decreased because the O2 can't get to the blood as easy-this increases the A-a gradient

Edema will also raise the A-a gradient because again it is harder to get the O2 to the blood so arterial blood will decrease in O2 while alveolar is the same or higher.
Definition
explain which of these 4 things will alter A-a gradient and why?
1) high altitude
2)hypoventilation
3)increased thickness of lung
4)edema
Term
alveolar ventilation - arterial PaO2 (from the arterial blood gas lab test)
Definition
how do you calculate the A-a gradient?
Term
less that 15 mmHg
Definition
what is a normal A-a gradient in a healthy individual?
Term
diagnosing causes of hypoxemia

(according to Gaddis: hypoventilation, V/Q mismatch, diffusion issues, Shunt)
Definition
what does the A-a gradient help with?
Term
V/q mismatch
widens A-a gradient
causes hypoxia
Definition
if a patient does not have a history of diffusion issues, what could be to blame? what does this do to A-a gradient? to the patient?
Term
dissolved in plasma OR
bound to Hemoglobin

PaO2 measures the plasma partial pressure
Definition
how is oxygen transported in the blood? what does PaO2 measure?
Term
no! the A-a gradient doesn't have to do with O2 bound to hemoglobin, just plasma. Decreased RBC's will not affect it.
Definition
does Anemia alter the A-a gradient? why?
Term
plasma <2%, 0.3 mL/dL Hb >98% 19.7 mL/dL total is 20 mL/dL
Definition
how many mL/dL of blood is O2 dissolved in arterial blood plasma? bound to Hb? what are the percents? what is the total PO2 in blood?
Term
oxyhemoglobin
Definition
Hb + O2 = ?
Term
each iron binds 1, so 4 total

also remember the 2 alpha, 2 beta subunit business
Definition
how many O2 can each iron bind on hemoglobin molecules? how many is that total per Hb molecule?
Term
BLUE
Definition
what color is hemoglobin when it is not bound to O2?
Term
conformational changes that assist loading of oxygen
Definition
how does binding of 3 O2 molecules increase the binding of the 4th to hemoglobin?
Term
CO2
Definition
does de-oxy hemoglobin have a higher affinity for O2 or CO2?
Term
15 g Hb/dL blood
Definition
how much Hb/dL blood does a person normally have?
Term
1.35 mL
Definition
how many mL O2 can 1 g of Hemoglobin bind?
Term
if all Hb are fully loaded 15g/dL * 1.35 mL O2/g = 20.1 mL O2/dL
Definition
if you have 15 g of hemoglobin with the ability to bind 1.35 mL O2, what is your oxygen carrying capacity?
Term
[image]
Definition
what's the dissociation curve of oxyhemoglobin look like?

what shifts this curve, and in what directions?
Term
pressure at which Hb is 50% saturated (usually around PO2 = 27 mmHg)
Definition
what is p50?
Term
resting cell: 40 mmHg at 75%
alveoli: 100 mmHg at 97%
Definition
what is PO2 of a resting cell & its percent O2 saturation of Hb? how about alveoli?
Term
Henry's law
Definition
increasing PO2 increases dissolved O2, what law accounts for this?
Term
0.3 mmHg
Definition
what is O2 carrying capacity for arterial plasma?
Term
venous: 75% + excercise: 30% (lower because excercising tissue needs to unload O2) arterial: 97%
Definition
what is the 02 saturation of venous blood? with excercise? arterial blood?
Term
carrying capacity of oxygen, ~20 mL/dL
Definition
what is CaO2?
Term
15.3 mL O2 = .75 * (20mL/dL)
Definition
what is the O2 carrying capacity of venous plasma?
Term
4.7 mL/dL
Definition
how much O2 does your body extract from blood during resting conditions?
Term
5 mL/min (250/4.7)
250 is amount consumed, 4.7 = amount used at rest

plasma would be like 250/.3 so 83 L/min or something crazy
Definition
if normal O2 consumption at rest is 250 mL O2/min, what is cardiac output to satisfy this? what would it be if this were plasma O2?
Term
percent saturation of hemoglobin with oxygen (y axis of O2 sat curve)
Definition
what is SvO2?
Term
total oxygen content of mixed venous blood
Definition
what is CvO2?
Term
composition of air, alveolar ventilation, & efficiency of gas exchange

amount of Hb-# of Hb molecules, number of functional RBC's, blood volume
Definition
what is amount of O2 bound to hemoglobin determined by? what is the amount of hemoglobin determined by?
Term
Hematocrit normal is 40-50%
Definition
ratio of red blood cells to plasma.

 what is the normal range of this?
Term
anemia
Definition
decrease in hemoglobin and thus a decrease in O2 carrying capacity of the blood
Term
polycythemia - RBC's plug up capillaries
Definition
increased above normal amounts of RBC's hematocrit concentration is 60-70%
Term
erythropoietin
released by kidneys in response to low oxygen levels (hypoxia)
Definition
glycoprotein that increases # of RBC's

what is it?
where is it released?
what triggers it's release?
Term
proerythroblasts
Definition
low tissue oxygenation -> Erythropoietin -> hemopoeitic stem cells -> ________ -> RBC -> increased tissue oxygenation
Term
go to high altitude, make a bunch more RBC's and you can carry more O2
Definition
how do you blood dope?
Term
increased CO2, increased H+ (decreased pH), increased DPG, and increased temperature this would occur when a person is exercising so the O2 can unload better
Definition
what causes a "right shift" and in what conditions would this occur?
Term
CO & cold temperatures
Definition
what causes a left shift of the oxy hemoglobin dissociation curve?
Term
Bohr effect-changes in pH, PCO2, and temp can alter binding affinity for O2
Definition
increased H+ causes a rightward shift, good for unloading O2
Term
it makes it harder, hypoxia stimulates DPG production which creates a right shift
Definition
does a left shift make it harder or easier to unload O2 from blood? what could cause this?
Term
Carbon Monoxide
Definition
what has a 200x greater affinity for hemoglobin that O2?
Term
O2 saturation looks normal because O2 is bound to Hb, it just cannot unload, therefore tissue O2 will be low
Definition
with CO poisoning, what happens to SaO2? tissue O2 level?
Term
1) dissolved in plasma ~7%
2) bound to Hb(carbamino Hb) ~23%
3) in the form of bicarbonate (HCO3-) 70%
Definition
name the 3 ways CO2 is carried in the blood
Term
bicarbonate
Definition
allows CO2 to travel in the blood and acts as a buffer system
Term
carbonic anhydrase in the RBC!
Definition
how does CO2 and water make bicarb?
Term
some kind of Chloride ion exchange deal
Definition
how is bicarb transported out the RBC when it is made?
Term
H+
Definition
what else binds to hemoglobin besides O2, CO, and CO2?
Term
it is steeper, 6/4 vs 60/4.7
it is not sigmoidal, its more linear
Definition
how does the CO2 dissociation curve differ from the O2 curve?
Term
Deoxygenation of the blood increases its ability to carry carbon dioxide. Conversely, oxygenated blood has a reduced capacity for carbon dioxide.
Definition
what is the Haldane effect?