Final answer:
At a 19.5% oxygen concentration, hemoglobin in red blood cells efficiently transports oxygen throughout the body, much greater than what would be possible with dissolved oxygen alone. In emergency medical situations, synthetic oxygen carriers can serve as a temporary replacement for blood to provide oxygen to tissues.
Step-by-step explanation:
At an oxygen (O₂) concentration of 19.5%, which is slightly less than the normal atmospheric concentration, the body still carries out efficient oxygen transport due to the presence of hemoglobin in red blood cells. Hemoglobin has a high affinity for O₂ and each molecule can bind up to four oxygen molecules, greatly increasing the total dissolved oxygen concentration in the blood compared to what would be possible with dissolved oxygen alone.
Synthetic oxygen carriers, like those based on fluorinated alkanes, have been developed to mimic the function of hemoglobin, offering high Henry's law constants for O₂ which facilitate oxygen transport in emergency situations as blood substitutes. They do not require refrigeration and have a long shelf life, but are generally used as a short-term solution.
Therefore, even at a slightly reduced oxygen concentration, the body maintains proper function through the use of hemoglobin, and in medical situations, synthetic oxygen carriers can provide support.