Deoxygenated blood is darker.
Understanding Blood Color
While blood is always red, its shade varies depending on the level of oxygen saturation. The difference in color arises because hemoglobin, the protein in red blood cells responsible for carrying oxygen, changes its structure when it binds to oxygen.
Oxygenated Blood (Arterial Blood)
- Color: Bright red
- Location: Primarily found in arteries, which carry blood away from the heart.
- Oxygen Content: High in oxygen.
- Hemoglobin State: Hemoglobin is bound to oxygen.
Deoxygenated Blood (Venous Blood)
- Color: Dark red
- Location: Primarily found in veins, which carry blood back to the heart.
- Oxygen Content: Low in oxygen.
- Hemoglobin State: Hemoglobin has released its oxygen.
Why the Confusion?
The misconception that deoxygenated blood is blue often arises from the way veins are depicted in anatomical illustrations and diagrams. These diagrams typically use blue to represent veins for clarity, making them easily distinguishable from the red arteries. However, the blood within veins is not blue. It is simply a darker shade of red.
Practical Observation
Anyone who has had their blood drawn for medical tests or has donated blood can attest to the dark red color of deoxygenated blood. This is because the blood being drawn is venous blood.
