The primary carrier of oxygen in the blood is hemoglobin, a protein found in red blood cells. Hemoglobin binds to oxygen in the lungs and transports it to tissues and organs throughout the body, facilitating cellular respiration and energy production. Each hemoglobin molecule can carry up to four oxygen molecules, making it highly efficient in oxygen delivery. Additionally, hemoglobin plays a role in transporting carbon dioxide from tissues back to the lungs for exhalation. Understanding hemoglobin's function is crucial for insights into respiratory health and conditions such as anemia.