Hemoglobin is primarily found in the red blood cells of vertebrates, where it functions as the protein responsible for transporting oxygen from the lungs to body tissues and carrying carbon dioxide back to the lungs for exhalation
. In humans, hemoglobin makes up about 96% of the dry weight of red blood cells and is present at a concentration of approximately 12 to 20 grams per 100 mL of blood
. Additionally, hemoglobin is also found in other cells such as certain neurons, macrophages, alveolar cells in the lungs, and some epithelial cells, where it plays roles in oxygen absorption and iron metabolism regulation
. In summary, you would find hemoglobin mainly in:
- Red blood cells circulating in the bloodstream
- Various other cell types including lung alveolar cells, certain neurons, and macrophages
This distribution allows hemoglobin to efficiently facilitate oxygen transport and participate in other cellular functions related to oxygen and iron
