Aerospace Physiology 25-07 Practice Test

The main concept is how oxygen and carbon dioxide are transported in the blood, primarily by a protein inside red blood cells. Hemoglobin is the iron-containing protein in red blood cells that binds oxygen in the lungs and releases it to tissues where needed. It also picks up carbon dioxide, a waste product from tissues, and helps remove it by carrying it back to the lungs to be exhaled. Hemoglobin can carry oxygen as oxyhemoglobin and carbon dioxide in various forms, including carbaminohemoglobin or as bicarbonate after its conversion in the red blood cells. The other options don’t perform this transport role: platelets are involved in clotting, not gas transport; plasma is the liquid component that carries dissolved substances but does not actively transport most oxygen and carbon dioxide; myoglobin stores oxygen in muscle tissue rather than transporting it throughout the body.