Healthy blood is red. This is because of hemoglobin, a protein within red blood cells that binds to oxygen. Oxygenated hemoglobin reflects red-orange light, giving blood its characteristic color.
Why is Blood Red?
The color of blood is determined by the interaction of light with the hemoglobin molecules within red blood cells. Hemoglobin contains iron, and when this iron binds to oxygen, it reflects red-orange light, resulting in the red appearance of blood. As stated in one reference, "When iron reacts to oxygen, it becomes red. That interaction is what gives blood its red color." (Cleveland Clinic). It is important to note that the perception of color is based on the wavelengths of light reflected by the object, as opposed to the object having an intrinsic color. (Reference 08-Jan-2022).
Misconceptions about Blood Color
A common misconception is that deoxygenated blood is blue. This is false. All blood in the human body is red, although the shade may vary slightly depending on the oxygen saturation level. Deoxygenated blood is a darker red, but it is still red. This is confirmed by several sources that explicitly state that deoxygenated blood is not blue. (Medical News Today)
The Role of Red Blood Cells
Red blood cells, also known as erythrocytes, are the primary carriers of oxygen throughout the body. Their function is crucial for delivering oxygen to tissues and removing carbon dioxide. This process is essential for energy production and maintaining overall body health. (Cleveland Clinic, University of Rochester Medical Center)
