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Bohr Effect vs. Haldane Effect: What's the Difference?

By Janet White || Published on April 18, 2024
The Bohr effect describes how increased CO2 levels lower blood pH and decrease hemoglobin's oxygen affinity, while the Haldane effect explains how deoxygenated blood enhances CO2 transport.

Key Differences

The Bohr effect, named after Christian Bohr, refers to the physiological phenomenon where increased carbon dioxide (CO2) levels cause a decrease in blood pH, leading to hemoglobin's reduced affinity for oxygen. This effect is crucial in facilitating oxygen unloading in tissues. Conversely, the Haldane effect, named after John Scott Haldane, describes how the oxygenation state of hemoglobin influences its ability to carry CO2. Deoxygenated blood can carry more CO2, which is beneficial for transporting CO2 from tissues to the lungs.
In the Bohr effect, the presence of CO2 and hydrogen ions (H+) alters the shape of hemoglobin, making it less likely to bind to oxygen. This mechanism is essential in active tissues where CO2 production is high, allowing more oxygen to be released. The Haldane effect complements this by facilitating CO2 transport: when hemoglobin releases oxygen, its ability to bind to CO2 and H+ increases, helping in the removal of these waste products.
The Bohr effect is influenced by factors like temperature and 2,3-bisphosphoglycerate (2,3-BPG), which further modulate oxygen affinity. In higher temperatures, such as in metabolically active tissues, the Bohr effect is more pronounced. The Haldane effect, on the other hand, is significant in the lungs where oxygenated blood has a reduced capacity to carry CO2, aiding in CO2 exhalation.
The Bohr effect plays a crucial role in adjusting oxygen delivery during various physiological conditions like exercise, altitude, and disease states. The efficiency of oxygen unloading in tissues is directly influenced by this effect. The Haldane effect is essential for CO2 transport efficiency, especially in conditions where CO2 production is altered, such as during intense physical activity or respiratory diseases.
The Bohr effect primarily deals with oxygen affinity changes in response to pH and CO2 levels, the Haldane effect focuses on the capacity of deoxygenated blood to transport CO2. Both effects are vital for maintaining efficient gas exchange and homeostasis in the body.

Comparison Chart


Decreased oxygen affinity of hemoglobin in response to lowered pH and increased CO2
Increased CO2 carrying capacity of deoxygenated blood

Primary Influence

PH and CO2 levels
Oxygenation state of hemoglobin

Physiological Role

Facilitates oxygen unloading in tissues
Enhances CO2 removal from tissues

Influencing Factors

Temperature, 2,3-BPG levels
Oxygen levels in the blood

Clinical Relevance

Adjusts oxygen delivery during exercise, altitude changes, and disease
Important in CO2 transport during physical activity and respiratory conditions

Bohr Effect and Haldane Effect Definitions

Bohr Effect

This effect is a blood oxygenation regulation mechanism influenced by carbon dioxide levels.
The Bohr effect is critical in managing oxygen transport during respiratory distress when CO2 levels are imbalanced.

Haldane Effect

The Haldane effect describes the increased capacity of deoxygenated blood to carry carbon dioxide.
Thanks to the Haldane effect, more CO2 is transported from the muscles to the lungs during intense exercise.

Bohr Effect

The Bohr effect modulates oxygen delivery to different parts of the body based on metabolic needs.
In the human body, the Bohr effect adjusts oxygen supply to meet the demands of various tissues.

Haldane Effect

It explains how hemoglobin's affinity for CO2 is inversely related to its oxygenation.
The Haldane effect facilitates CO2 excretion in the lungs by reducing CO2 affinity in oxygen-rich blood.

Bohr Effect

It is a physiological mechanism where hemoglobin releases more oxygen under acidic conditions.
The Bohr effect is evident in the body’s response to intense physical activity, where increased acidity enhances oxygen delivery to muscles.

Haldane Effect

This effect is crucial for maintaining acid-base balance in the body through CO2 transportation.
The Haldane effect contributes to the body's overall pH regulation by managing CO2 levels in the blood.

Bohr Effect

The Bohr effect represents hemoglobin's response to changing blood gas conditions, mainly CO2 and pH variations.
The Bohr effect ensures efficient oxygen supply during high altitude adaptation by responding to altered blood gas levels.

Haldane Effect

The Haldane effect refers to the enhanced CO2 transport efficiency in blood with lower oxygen levels.
In areas of low oxygen, such as tissues using up oxygen, the Haldane effect ensures efficient CO2 removal.

Bohr Effect

The Bohr effect describes the reduction in hemoglobin's oxygen-binding affinity due to increased carbon dioxide and decreased pH.
In exercising muscles, the Bohr effect allows more oxygen to be released due to the high CO2 production.

Haldane Effect

The Haldane effect influences how blood carries and releases carbon dioxide based on its oxygenation state.
In respiratory diseases, the Haldane effect plays a key role in compensating for altered CO2 and oxygen levels.


Why is the Bohr Effect important?

It's crucial for efficient oxygen transport and release in areas of the body where it's most needed, like active muscles.

How does the Bohr Effect impact oxygen delivery?

The Bohr Effect facilitates oxygen delivery to tissues where CO2 is high and pH is low, as hemoglobin releases more oxygen under these conditions.

How does the Haldane Effect aid in CO2 transport?

It enhances CO2 removal from tissues by increasing the blood's capacity to carry CO2 in the absence of oxygen.

What is the Bohr Effect?

The Bohr Effect describes how a decrease in blood pH or an increase in carbon dioxide concentration lowers the affinity of hemoglobin for oxygen.

What physiological conditions demonstrate the Haldane Effect?

The Haldane Effect is evident in tissues where oxygen is being utilized, allowing more CO2 to bind to hemoglobin and be transported away.

What role does hemoglobin play in the Haldane Effect?

Hemoglobin binds more readily to CO2 and protons when it's deoxygenated, a key aspect of the Haldane Effect.

What is the Haldane Effect?

The Haldane Effect refers to the increased capacity of deoxygenated blood to carry carbon dioxide, compared to oxygenated blood.

What triggers the Bohr Effect?

The Bohr Effect is triggered by changes in pH and CO2 levels in the blood.

Can the Bohr Effect be altered?

Yes, conditions like carbon monoxide poisoning or certain diseases can alter the Bohr Effect.

Does the Bohr Effect affect all oxygen-binding proteins?

No, the Bohr Effect is specific to hemoglobin and a few other oxygen-binding proteins.

What role does carbon dioxide play in the Bohr Effect?

Increased CO2 levels lower blood pH, which reduces hemoglobin's affinity for oxygen, a central part of the Bohr Effect.

How does the Haldane Effect function in the lungs?

In the lungs, oxygenated blood decreases its affinity for CO2, facilitating CO2 exhalation.

Does the Haldane Effect occur in artificial oxygen carriers?

The Haldane Effect is specific to hemoglobin, so it's not present in artificial oxygen carriers.

Are the Bohr and Haldane Effects relevant in clinical settings?

Yes, they are important in understanding respiratory physiology and managing conditions like respiratory and metabolic acidosis.

Is the Haldane Effect observed in all animals?

The Haldane Effect is observed in animals with hemoglobin-based blood, but its extent can vary.

What is the relationship between the Bohr and Haldane Effects?

They are complementary; the Bohr Effect assists in oxygen release and CO2 uptake, while the Haldane Effect aids in CO2 release and oxygen uptake.

Does the Bohr Effect influence exercise performance?

Yes, during exercise, increased CO2 and decreased pH enhance oxygen delivery to muscles due to the Bohr Effect.

How does temperature affect the Bohr Effect?

Higher temperatures can enhance the Bohr Effect by reducing hemoglobin's affinity for oxygen.

Is the Haldane Effect always beneficial?

While generally beneficial for gas exchange, abnormal blood conditions can sometimes diminish its effectiveness.

Can the Bohr Effect impact blood pH?

Indirectly, yes; the Bohr Effect is influenced by pH but can also contribute to pH changes through its effect on CO2 and oxygen binding.
About Author
Written by
Janet White
Janet White has been an esteemed writer and blogger for Difference Wiki. Holding a Master's degree in Science and Medical Journalism from the prestigious Boston University, she has consistently demonstrated her expertise and passion for her field. When she's not immersed in her work, Janet relishes her time exercising, delving into a good book, and cherishing moments with friends and family.

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