Arterial Blood: Understanding the Science Behind Its Bright Red Color

Bright red arterial blood contains oxygenated hemoglobin. Hemoglobin is a protein found in red blood cells that carries oxygen from the lungs to the rest of the body. When hemoglobin is oxygenated, it is bright red. Deoxygenated hemoglobin, which is found in venous blood, is a darker red color.