Review Objective 104. What are the distinctions between systemic and pulmonary circulatory patterns?

Why do oxygen and carbon dioxide move in the directions indicated by the arrows?

The hemoglobin molecule (Fig )

It will help us understand the role of hemoglobin if we know how hemoglobin is studied in the lab.

Oxygen-hemoglobin saturation curve. Fig a

Choose a Po 2 value, go up to the curve, then read across to the value of the % saturation.

How do we use this curve to understand hemoglobin’s ability to deliver oxygen from the lungs to the tissues? We need to know the % saturation of hemoglobin in the lungs and in the tissues. We need to remember that an increase in % saturation means that hemoglobin has picked up O 2. (Where did the O 2 come from?) We need to remember that a decrease in % saturation means that hemoglobin has released O 2. (Where did the O 2 go?)

What Po 2 values are shown ?

Po 2 values Pulmonary Arteries = 40 mm Hg Blood goes through pulmonary capillaries Pulmonary Veins =100 mm Hg Systemic Arteries = 95 mm Hg Blood goes through systemic capillaries Systemic Veins = 40 mm Hg

13b. How much of the hemoglobin lost its oxygen in going from systemic arteries to systemic veins? LocationPo 2 % saturation Systemic arteries 95 mm Hg97% Systemic veins 40 mm Hg75% Difference22%

This means that 22% of the hemoglobin loses its oxygen as it passes from the systemic arteries to the systemic veins. Where does this oxygen go?

This means that oxygen is released to cells when the per cent saturation of hemoglobin decreases.

There is something about this curve that should bother you.

What is the functional significance of the distinctive shape of this curve?

Now let’s consider other experiments that provide more information on hemoglobin’s ability to transport oxygen. Change the pH Change the pCO 2 Change the temperature Use a different hemoglobin (let’s try from a fetus!) Use a different respiratory pigment (let’s try myoglobin, a monomeric respiratory pigment found in muscle fibers)

Increasing the pCO 2 or [DPG] has the same effect as decreasing the pH. (see Figs & 10.35)

See Fig

Where in the circulatory system would you expect these shifts to occur?

Note the difference between the curves of hemoglobin and myoglobin. See Fig for an explanation.