Exam 3 - Lecture 3 Flashcards
What is the solution?
BLOOD
2 forms of oxygen are
dissolved and bound
What is dissolved oxygen?
How much oxygen is forced into solution
Why does oxygen have a low dissolved content?
Not very soluble
The dissolved oxygen PO2 should be the same as
environment (? he said this, don’t get it tbh)
What is the force that pushes oxygen into solution?
PO2
How is oxygen measured in solution
measured in mL O2/mmHg/dL of solution
What is the normal oxygen concentration per dL of solution?
.003mL O2/mmHg/dL
What’s the oxygen concentration if you put it in per mL of solution?
.00003mL O2/mmHg/mL
Quantity of dissolved oxygen is always measured in
volume such as mL/dL/L
Dissolved O2 determines ___, which is what drives O2 _____
PO2; on and off hemoglobin
what is the solubility coefficient of oxygen?
.003mL O2/mmHg/dL blood
If PO2 = 100 mmHg, then what’s the concentration of dissolved oxygen in the blood?
100 x .003 = .3mL O2/dL
Is dissolved oxygen quantity enough to meet metabolic demands?
Absolutely fucking not (~250mL/min)
this is why hemoglobin is so crucial
Hemoglobin binding capacity
1.34mL O2/g of Hb
Normal Hb is ___, which is how much bound oxygen?
What is this called?
15g/dL
15 x 1.34 = 20.1mL O2/dL
Oxygen-carry capacity of hemoglobin
Total oxygen content = __ + ___
Dissolved + bound oxygen
0.3 + 20.1 = 20.4mL O2/dL
What is the PVO2?
40mmHg (PO2 concentrations in venous blood)
In venous blood, what is the dissolved oxygen content?
40 x 0.003 = 0.12mL/O2/dL
What is the amount of bound o2 content in venous blood?
15mL/O2/dL
Total oxygen content in venous blood?
0.12 + 15 = 15.12mL/O2/dL
Saturation determines what?
How much of the carrying capacity is utilized
at 90% O2 sat, what is the bound Hb?
90% x 20.1 = 18.09mL O2/dL
What is a normal Hb per this class? how does it differ between populations?
15g/dL
Men more, women less
What is HbA and what are the subunits?
adult Hb; its a tetramer with 2 alpha and 2 beta subunits
Binds 4 O2 molecules
What is HbF and what are its units?
Fetal Hb; 2 alpha and 2 gamma subunits
Which Hb has a higher affinity for O2?
What shift does this mean on the curve?
Fetal -> left shift
Why does one Hb have more affinity than the other?
HbF has a higher affinity to extract O2 from maternal blood in the placenta. If it had the same affinity, oxygen wouldn’t be motivated to leave HbA for HbF
When is HbF replaced?
quickly after birth
EPO is produced by what? What does it do?
Erythropoietin is produced by the kidney
Regulates RBC and Hb production
What condition would require synthetic EPO?
Renal failure
Myoglobin has a similar structure to Hb, but what’s the main difference in structure?
only has 1 binding site
Explain myoglobins affinity for O2 in comparison to HbA and what kind of shift it creates
Higher affinity for O2 than HbA, left shifted.
What main 2 things does myoglobin do?
Stores O2 in red skeletal muscle
helps unload O2 into working muscle cells
What does myoglobin contain and what feature does that result in?
Contains iron, this is why red meat is red.
How does carbon monoxide (CO) affect O2 carrying capacity?
Decreases it by binding to O2 sites with high affinity.
How does CO binding affect O2 at the tissue level?
CO bound to Hb increases Hb affinity for remaining O2, therefore it DECREASES O2 UNLOADING AT TISSUES
How does CO binding affect curve?
Left shift with a lower plateau
How do you treat CO poisoning?
100% O2 to competitively displace CO binding
According to oxy-hemoglobin curve, what are normal conditions? (Arterial/venous PO2, Sat, content #’s)
Arterial: 100mmHg, 97-100%, 20mL /O2/dL
Venous: 75mmHg, 75%, 15mL O2/dL
What are the exceptions in coronary circulation?
What does this indicate?
Venous O2 sat drops to 25% because heart extracts 75% of O2
Not much reserve, high vulnerability to ischemia
What does a right shift on the oxy-hemoglobin curve mean?
What conditions have a right shift?
Decreased affinity for O2, which makes O2 unloading easier
↑ CO2
↓ pH (↑H⁺)
↑ temperature
↑ 2,3-BPG
What does a left shift on the oxy-hemoglobin curve mean?
What conditions have a left shift?
Increased affinity for O2, makes unloading more difficult.
↓ CO2
↑ pH
↓ temp
↓ 2,3-BPG
- Fetal Hb, myoglobin, CO
Increased metabolism will result in what physiologic changes, which results in what? (annoying card, prob have to see answer first to know what im asking, sorry)
Increased CO2, H+, Temperature -> Right shift on curve -> Results in the beautiful compensation of more O2 unloading into the tissues
What shift would venous blood have? why?
Its more acidic, so right shift
Sick patients may have a venous saturation of ____ or even lower.
60% instead of 75%
What is P50?
PO2 needed for 50% Hb saturation
What is a normal P50?
26.5 mmHg
Right shift on the curve does what to the P50?
Left shift?
Right shift = increased P50
Left shift = Decreased P50
What does an increased/decreased P50 even mean?
Increased means you need more O2 to saturate Hb, and a decrease would mean you need less.
a right shift means you need more or less O2 to saturate Hb?
Right shift = Increased P50 = More O2
opposite is true for left shift.
What are the 3 forms of CO2 in the blood?
Dissolved, Carbamino compounds, Bicarbonate
What are the arterial concentrations of each type of CO2?
Dissolved: 5%
Carbamino: 5%
Bicarb: 90%
what is the solubility of dissolved CO2 in the arteries?
0.06mL CO2/mmHg/dL
at 40mmHg PCO2 -> .06 x 40 = 2.4mL/dL
CO2 binds to _____ on proteins, mainly Hb
Terminal amine groups
These are the CO2 carbamino compounds
CO2 + H2O ⇌ H2CO3 ⇌ ?
H⁺ + HCO3⁻
? ⇌ H2CO3 ⇌ H⁺ + HCO3⁻
CO2 + H2O
What is bicarb catalyzed by?
Carbonic anhydrase
What is the venous blood composition of CO2?
10% dissolved, 30% carbamino, 60% bicarb
52.5mL/dL
What is the total CO2 content of arterial blood?
48 mL/dL
How much bicarbonate CO2 is present in 500mL of venous blood under normal conditions?
Just take the % composition and multiply total content # to get mL/dL
ex: 0.60 x 52.5 = 31.5 mL/dL
That’s per dL. there are 5 dL in 500mL, so now times that by 5.
Final answer: 157.5mL
What’s the Haldane effect?
The Haldane effect is when deoxygenated blood can carry more carbon dioxide than oxygenated blood.
Less O2 = More CO2 carried
More O2 = less CO2 carried
In the lungs, what promotes CO2 release? (r/t Haldane effect)
O2 loading promotes CO2 release
CO2 and O2 loading/unloading are ____.
Interdependent
Final concept integration:
Dissolved O2 sets PO2, which will drive
Hb saturation
HbF and myoglobin have higher affinity which results in what shift?
Left
Carbon monoxide does TWO things to Hgb
Decreases O2 capacity AAANNDDDD unloading efficiency
P50 gives us insight into _______
how willing Hb is to bind to O2
O2 unloading helps with
CO2 loading
and vice versa
What has the lowest venous O2 sat?that
Coronary circulation due to extreme demand
25% venous sat
A patient’s coronary circulation receives arterial blood at 97% O₂ saturation, and venous blood returns at 24% O₂ saturation.
If the hemoglobin concentration is 15 g/dL, how much O₂ is extracted per dL of coronary blood flow?
(Ignore dissolved O₂ for this calculation.)
Hb binding capacity: 1.34mL/O2/g of Hb
1.34 x 15g x 0.97 = 19.497mL O2/dL
then:
1.34 x 15g x 0.24 = 4.824mL O2/dL
subtract them from eachother
final answer: 14.673mL/dL
It’s important to note that he will also probably adjust the Hb level. don’t just assume 15 unless he states under normal conditions
A patient’s hemoglobin is 15 g/dL, but 20% of it is bound by carbon monoxide (CO), reducing available sites for O₂.
Arterial O₂ sat = 100%
Venous O₂ sat = 50%
How much O₂ is extracted per dL of blood?
real O2 sats = 80% and 30%
1.34 x 15 x 0.8 = 16.08mL/dL
1.34 x 15 x 0.3 = 6.03mL/dL
16.08 - 6.03 = 10.05mL/dL were extracted
A patient has:
PO₂ = 100 mmHg
Hb = 15 g/dL
Arterial O₂ sat = 98%
How much O₂ is dissolved in plasma per dL?
use dissolved O2 arterial coefficient of .003mL/O2/mmHg/dL
.003 x 100 = 0.3mL O2/dL
the sat has nothing to fucking do with this because dissolved oxygen is independent of Hb saturation, duh!!!
A patient has:
-Hb = 10 g/dL
-CO occupies 25% of Hb binding sites
-O₂ saturation is 90%
How much O₂ is bound per dL of blood?
Since 25% of sites are bound by CO, that leaves 75% sites remaining for O2
Of those sites, only 90% O2 is bound.
10 (Hb levels) x .75 = 7.5
7.5 x 1.34 x 0.9 = 9.045mL O2/dL
side note to make it relate to real world and help it make sense: patient would be showing a sat of 90% on the monitor. but only 75% of the sites are O2
0.9 x 0.75 = 0.675
0.675 x 10 x 1.34 = 9.045, same answer!
