Oxygen transport Flashcards
what are the 2 ways oxygen is transported in the blood?
A) 2% is dissolved in plasma
B) 98% is chemically bound to hemoglobin
100 ml blood contains _____ mL of DISSOLVED oxygen at PO2 = 100 mmHg
(this is asking about O2 in plasma, not Hb bound)
0.3 ml
Each gram of Hb can combine with ____ ml of oxygen
1.34 ml
Normally, blood contains ≈ ___g Hb/100ml of blood
15g Hb/100ml of blood
- or 150g/L
oxygen carrying capacity of Hb is __ ml oxygen/100 ml blood
in other words, how much oxygen can 100ml of blood carry?
20 ml
15 X 1.34 = 20 ml oxygen/100 ml blood
The amount of oxygen in the blood (sum of both forms, dissolved and bound to hemoglobin) is called the “____________”
oxygen content of blood
T/F:
A) The O2 content of arterial blood (CaO2) is ≈ 15 vol%
AND
B) the O2 content of venous blood (CvO2) ≈ 10 vol%
False
Arterial = 20 vol%
Venous = 15 vol%
both oxygen carrying capacity and oxygen content depend on what?
how are these values expressed?
the amount of hemoglobin in an individual’s blood
are expressed as volume of oxygen present per unit volume of blood
the SaO2 (hemoglobin saturation ratio) is expresses a _________, not a ___________
the SaO2 expresses a percentage and not a unit volume of oxygen
T/F: SaO2 and oxygen content are interchangeable
FALSE
two patients may have the same SaO2 but one could have a low blood hemoglobin concentration because of anemia
Venous blood entering the pulmonary capillaries has a PO2 of ____ mm Hg; and the Hb is ____% saturated with oxygen
40 mm Hg
Hb is 75% saturated with oxygen
what is the alveolar PO2?
100 mmHg
after equilibration in the lungs, what is the % saturation of hemoglobin?
97%
In the plateau region, at a PO2 _______ mmHg, there is little change in amount of O2 bound to Hb
plateau region = PO2 60-100 mm
T/F: increasing PO2 beyond 100 mmHg does not improve oxygen carriage by Hb significantly
true
The oxyhemoglobin dissociation curve is very steep between PO2 = ___-___ mmHg
60-20 mm Hg
what is the SaO2% at 100mmHg? what about 60mmHg? 27mmHg?
A) 100mm = 99%
B) 60mm = 90%
C) 27mm = 50%
At normal body temperature of 37°C, arterial blood with a pH of 7.4, a PCO2 of 40 mmHg, what is the P50 for hemoglobin?
27 mmHg
so at 27mmHg, 50% of Hb is not bound to oxygen
When the affinity of hemoglobin for oxygen decreases (P50 increases), does the curve shift left or right?
decreased affinity = shift to the right
- increases unloading of O2
what can shift the P50 curve to the RIGHT?
1) ↑[H+],↓pH
2) ↑ PCO2 (Bohr Shift)
3) ↑ temperature
4) ↑ 2,3 DPG (2,3 DPG=2,3 diphosphoglycerate
How does Anemia effect Oxygen transport in the blood? what remains the same? what is changed?
A) The association of oxygen and Hb expressed as % Hb
saturation is not affected
B) but, the association of oxygen and Hb expressed as arterial content of blood is reduced
How does Carbon Monoxide effect Oxygen transport in the blood?
1) The affinity of Hb for carbon monoxide is 240 times that for O2
2) CO competitively blocks the combination of oxygen with
Hb.CO bound Hb is called carboxyhemoglobin (HbCO)
T/F: CO shifts the oxyhemoglobin dissociation curve to the right
FALSE
shifts it to the LEFT
what is the color of oxygenated Hb? what about deoxygenated Hb? what about Hb bound to Carbon Monoxide?
A) Oxygenated Hb, HbO2 - bright red [e.g. normal arterial blood]
B) Deoxygenated Hb, Hb- blue [same as the color of systemic veins carrying venous blood]
C) Carboxyhemoglobin, COHb – cherry red [e.g. patient with CO poisoning]
_______ is defined as arterial blood with > 5g Hb/100ml in deoxygenated state and results in a bluish / purple discoloration of nail beds and mucous membranes
Cyanosis
why does the absence of cyanosis not always indicate normal oxygen transport?
A) an anemic patient with low oxygen in the blood may not appear cyanotic because he may not have sufficient deoxygenated Hb to appear cyanotic
B) patients with abnormally high levels of Hb, such as those with polycythemia may appear cyanotic
Carbon dioxide is transported in blood more readily than oxygen because carbon dioxide is ____ times more soluble than oxygen in plasma.
20x more soluble
what is the CO2 content of arterial blood? what about venous blood?
GIVE ANSWER IN %VOLUME
The CO2 content of arterial blood (CaCO2) is 48 vol%
The CO2 content of venous blood (CvCO2) is 52 vol%.
T/F: each time blood circulates through the body, 4 vol% of carbon dioxide is removed from the tissues and delivered to the lungs
true
what are the THREE ways CO2 is transported in the blood?
- physically dissolved [5 %*]
- physically dissolved as bicarbonate ion [ 90%]*
- combined with Hb as carbamino-compound [5%]*
T/F: Carbonic Anhydrase (CA) is an enzyme found in the blood cells and plasma that increases the formation of carbonic acid by over 1000X
FALSE
it is NOT found in plasma. Only found in RBC’s
Transport of CO2 is dependent on what?
O2 release
what is the Haldane effect?
The CO2 dissociation curve is influence by the state of oxygenation of the Hb
what causes the Haldane effect?
what does deoxygenated Hb better at doing than oxygenated Hb?
- deoxygenated Hb is better than oxygenated Hb in:
1) combining with hydrogen ions and in turn assisting the blood to load more CO2 from the tissues.
2) combining with carbon dioxide to form carbamino compounds and in turn assisting the blood to load more CO2 from the tissues for removal at the lungs.
what is the Bohr shift?
As CO2 leaves the tissue cells and enters the red blood cell, it causes more O2 to dissociate from Hb
T/F: As O2 passes from the alveoli into the red blood cells, Hb becomes saturated with O2 and becomes a stronger ACID
True
how does the increased acidity of Hb effect gas exchange?
The more acidic Hb releases more H+ that binds to more HCO3- to form carbonic acid
- the carbonic acid then reverts back to H2O and CO2
