Oxygen production of the water molecule) is released into the atmosphere. Oxygen is used in mitochondria to generate ATP during oxidative phosphorylation. The reaction for aerobic respiration is essentially the reverse of photosynthesis and is simplified as: In vertebrates, diffuses through membranes in the lungs and into red blood cells. Hemoglobin binds , changing color from bluish red to bright red ( is released from another part of hemoglobin through the Bohr effect). Other animals use hemocyanin (molluscs and some arthropods) or hemerythrin (spiders and lobsters). A liter of blood can dissolve 200 cm of . Until the discovery of anaerobic
Red blood cell second in human adults. The cells develop in the bone marrow and circulate for about 100–120 days in the body before their components are recycled by macrophages. Each circulation takes about 60 seconds (one minute). Approximately a quarter of the cells in the human body are red blood cells. Nearly half of the blood's volume (40% to 45%) is red blood cells. Packed red blood cells (pRBC) are red blood cells that have been donated, processed, and stored in a blood bank for blood transfusion. Almost all vertebrates, including all mammals and humans, have red blood cells. Red blood cells