Oxygen transport Flashcards by asw asw

what are the 2 ways oxygen is transported in the blood?

A) 2% is dissolved in plasma

B) 98% is chemically bound to hemoglobin

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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

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Each gram of Hb can combine with ____ ml of oxygen

1.34 ml

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Normally, blood contains ≈ ___g Hb/100ml of blood

15g Hb/100ml of blood

or 150g/L

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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

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The amount of oxygen in the blood (sum of both forms, dissolved and bound to hemoglobin) is called the “____________”

oxygen content of blood

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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%

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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

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the SaO2 (hemoglobin saturation ratio) is expresses a _________, not a ___________

the SaO2 expresses a percentage and not a unit volume of oxygen

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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

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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

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what is the alveolar PO2?

100 mmHg

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after equilibration in the lungs, what is the % saturation of hemoglobin?

97%

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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

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T/F: increasing PO2 beyond 100 mmHg does not improve oxygen carriage by Hb significantly

true

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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?

1. physically dissolved [5 %*] 2. physically dissolved as bicarbonate ion [ 90%]* 3. 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