Which of the following is the primary function of erythrocytes (red blood cells) in the human body?

• A. Secrete hormones that regulate blood pressure and fluid balance
• B. Produce antibodies to neutralize pathogens in the bloodstream
• C. Transport oxygen from the lungs to tissues and assist in carbon dioxide transport back to the lungs
• D. Initiate blood clotting by forming a platelet plug at sites of vascular injury

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the role of erythrocytes (red blood cells) in the circulatory system. Erythrocytes are specialized cells primarily involved in gas transport within the blood.
2. Step 2: Recall that erythrocytes contain hemoglobin, a protein that binds oxygen molecules in the lungs and carries them to tissues throughout the body.
3. Step 3: Recognize that erythrocytes also assist in transporting carbon dioxide, a waste product of cellular metabolism, from the tissues back to the lungs for exhalation.
4. Step 4: Compare the given options with the known functions of erythrocytes: hormone secretion, antibody production, oxygen and carbon dioxide transport, and blood clotting.
5. Step 5: Conclude that the primary function of erythrocytes is to transport oxygen from the lungs to tissues and assist in carbon dioxide transport back to the lungs, as this aligns with their physiological role.