Lecture 25 - Blood Gas Transport Flashcards Preview

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Flashcards in Lecture 25 - Blood Gas Transport Deck (18):

During exercise, what is responsible for increased O2 diffusion?

1) Increased surface area for diffusion - larger no. of capillaries open

2) More ideal V/Q ratio in the lungs (more ventilation)


What factors determine the PO2 of tissues?

Rate of transport of O2 to tissues

Rate of O2 consumption in the tissues


Describe the effects of blood flow and metabolic rate on peripheral tissue PCO2.

Increased blood flow (for example, in exercising tissues) will decrease PCO2, even though the tissues are putting out more CO2 through metabolism.


Compare O2 saturation in venous blood to arterial blood. How much is bound to heme groups?

O2 saturation of venous blood is approximately 75%.

O2 saturation in venous blood is approximately 97% (not 100% due to physiologic shunt).


Calculate the oxygen utilization coefficient.

Review this


Explain how Hb can be viewed as a tissue oxygen buffer system.

As a "buffer," the Hb is capable of REVERSIBLY binding oxygen and CO2. In the presence of low PO2 (i.e. at actively metabolizing tissues), the oxygen is off-loaded from the Hb into the tissue.


Relate PO2 and oxygen saturation to the oxygen-Hb dissociation curve.

When dealing with oxygen saturation, the % saturation is the amount of oxygen bound to Hb!

PO2 is the amount of free oxygen in blood.

As the PO2 increases, there is greater opportunity for oxygen to bind to Hb.


Relate pH to the O2-Hb dissociation curve.

Acidosis (decreased pH) is directly related to the presence of increased CO2. CO2 will dissociate to H+ and HCO3, which means that increased CO2 = lower pH.

Increased CO2 will shift the dissociation curve to the right, offloading oxygen and picking up CO2.


List and explain factors that shifts the O2-Hb dissociation curve to the right.

Increased Temp
Increased CO2
Increased BPG
Decreased pH


This is the change in oxygen-Hb binding due to changes in carbon dioxide/H+.

A. Haldane effect
B. Bohr effect
C. Oxygen-dissociation effect

B. Bohr effect


This leftward shift of the oxygen-Hb dissociation curve occurs in the _____.

A. lungs
B. tissues

A. lungs (decreased oxygen binding)


Approximately _____% of oxygen is transported as carbamino-Hb.

A. 7%
B. 23%
C. 70%

B. 23%


Appx. ____% of oxygen is transported by red blood cells as carbonic acid.

A. 7%
B. 23%
C. 70%

C. 70%


Binding of oxygen causes Hb to become a (weaker/stronger) acid. This produces a (lesser/greater) affinity to bind additional oxygen.



"click, click"


T/F: The binding of oxygen displacing carbon dioxide on Hb is known as the Haldane effect.



Due to a (lesser/greater) affinity of carbon monoxide to Hb, (more/less) CO will bind to Hb than O2.

greater, more


In CO poisoning, the blood is bright red, though the ____ is normal.

A. CO2
B. PO2
C. PO2

C. PO2


Describe the pressure difference that allows for oxygen diffusion from the alveolus to the pulmonary capillary.

Alveolar PO2 = 104 mmHg
Capillary PCO2 = 40 mmHg