Final answer:
The statement that the average life-span of an erythrocyte is approximately 120 days is true. Erythrocytes are recycled by phagocytic macrophages after circulating for about 120 days, playing a pivotal role in oxygen transportation in the body.
Step-by-step explanation:
The statement that the average life-span of an erythrocyte is approximately 120 days is true. Erythrocytes, also known as red blood cells, are released into the bloodstream as reticulocytes and then mature into erythrocytes.
These cells circulate in the body for around 120 days before they are removed and recycled by phagocytic macrophages mainly in the bone marrow, liver, and spleen. The removal process is crucial because old erythrocytes can become fragile and unable to navigate through the small capillaries, leading to their rupture and the subsequent recycling of their components, including hemoglobin.
The primary duty of erythrocytes is to carry and deliver oxygen to the body's tissues. These cells adapt remarkably for oxygen transport, as they lack nuclei and mitochondria, allowing for more hemoglobin and thus higher oxygen-carrying capacity. The surface glycoproteins and glycolipids present on erythrocytes contribute to the various blood types.