Oxygen DissociationCurves

An Introduction to Environmental Effects

on the structure ofHemoglobin

and their effects onOxygen Carrying Capacity

By Noel Ways

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Percent OxygenCarrying Capacity

of Hemoglobin

Interstitial Interalveolar

Partial Pressure of Oxygen

- +- +

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PrimaryStructure

SecondaryStructure

TertiaryStructure

Protein Structure Review

The Effect of Heat on Protein Structure

- + - +Temperature

Increase

Hydrogen bond unable to widthstand increases

movement and breaks. Protein is now altered.

An increase in positively charged protons (+) competes for the negative charge (-) and

breaks the hydrogen bond. The protein is now altered.

An increase in negatively charged hydroxyl ions (-) com-petes for the positive charge (+) and breaks the hydrogen bond.

The protein is now altered.

The Effect of Changing pH on Protein Structure

- + - ++

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+Acidosis

- + -- --

--

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+Alkalosis

Increase inMolecular Movement

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OxygenCarrying Capacity

of Hemoglobin

Interstitial Interalveolar

Oxygen Dissociation Curves for pH

CO2 + H2O H2CO3 H+ + HCO3 - H+ + HCO3 - H2CO3 CO2 + H2O

Body Cells Alveoli of Lungs

Interstitium Alveoli

The graphs below depict the dissociation curves under three different pH conditions.

A tissue with low metabolic activity. The environment is more alkaline, less O2 is released.

A tissue with moderate metabolic activity. The environement is being acidified, more O2 is being released.

A tissue with high metablic activity. The envronment is being further acidified and even more O2 is being released.

At the lungs , as CO2 is being lost the H+ concentration is likewise going down (pH is going up). As it does so the carrying capcity of hemoglobin rises and more oxygen can be attached to hemoglobin.

Among interstital cells ( , and ) as CO2 is produced which increases H+ and the interstitum is there-fore acidified (pH is going down). The lowering of the pH alters hemoglobin structure in such manor as to lower it’s oxygen carrying capacity. Therefore, oxygen is released. If metabolic continues to increases, more CO2 will be produced and the carrying capacity will be further lowered and even more O2 will be released.

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Partial Pressure of Oxygenm (pO2)

Partial Pressure of Oxygen

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Partial Pressure of Oxygen

Interstitial Interalveolar

Oxygen Dissociation Curves for Temperature

OxygenCarrying Capacity

of Hemoglobin

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Oxygen Carrying Capacityof Hemoglobin

Interstitial Interalveolar

Oxygen Dissociation Curve Compilation

Lower pHIncrease in Temperature

Higher pHDecrease in Temperature

Left Shift / Right Shift

This sigmoidal curve depicts the oxygen-carrying capacity of hemoglobin. It illustrates that by altering various physiological variables, the curve will exhibit either a “Left Shift” or a “Right Shift.” In this handout, we only dealt with two of these variables: pH and temperature.

We note that in metabolically active tissues there will be an increase in tem-perature and a lowering of the pH. This alters the structure of hemoglobin in such a manner as to release oxygen. Hemoglobin has less affinity for oxygen, and oxygen will be released. The curve shifts Right.

In tissues with lower metabolic activity, the temperature will be lower, and the pH will be higher. Under these conditions, the hemoglobin structure alters in such a manner as to absorb oxygen. Hemoglobin has a greater affinity for oxygen, and oxygen will be absorbed. The curve shifts Left.