Final answer:
Iron is released from macrophages through ferroportin channel proteins and binds to the plasma protein transferrin, which facilitates its transport in the blood to myeloid tissue for the production of red blood cells.
Step-by-step explanation:
Iron is released from macrophages through ferroportin channel proteins and travels to myeloid tissue bound to the plasma protein transferrin. Iron transport and utilization in the body are vital aspects of biology, especially concerning hemoglobin and red blood cell production. In the human body, iron is a crucial component of hemoglobin, the protein in red blood cells that carries oxygen.
After being absorbed, iron becomes part of the body's total iron pool and is stored in the liver or spleen as ferritin or hemosiderin. When new erythrocytes are needed, erythropoietin (EPO) stimulates the release of iron from storage. It is then bound to transferrin in the blood and transported to the red bone marrow. Here, it attaches to erythrocyte precursors for the production of new red blood cells.
Transferrin is the plasma protein that transports iron ions in the bloodstream, ensuring that they are delivered to the right tissues and cells. The iron that circulates in the blood and is bound to transferrin exchanges with the interstitial and intracellular compartments is also referred to as the 'labile iron pool.' The life cycle of iron within the human body continues as it reaches myeloid tissue for erythropoiesis—the process of creating new red blood cells. This cycle is essential for maintaining healthy levels of hemoglobin and, thus, ensuring efficient oxygen transport throughout the body.