Emergency Medical Technician (EMT) Intermediate Practice Exam

Which factors influence oxygen delivery to tissues?

1. Oxygen tension, blood volume, and body temperature

2. Ventilation rate, blood pH, and heart rate

3. Hemoglobin levels, cardiac output, and oxygen tension

4. Respiratory rate, carbon dioxide levels, and body fluids

The correct answer is: Hemoglobin levels, cardiac output, and oxygen tension

Oxygen delivery to tissues is influenced by several key physiological factors, and the chosen answer emphasizes those that are critical in ensuring adequate oxygenation. Hemoglobin levels are vital because hemoglobin is responsible for transporting oxygen from the lungs to the tissues. If hemoglobin levels are low due to anemia or other conditions, the capacity to carry oxygen efficiently decreases. Cardiac output also plays an essential role; it reflects the volume of blood the heart pumps per minute. If cardiac output is insufficient, even with adequate hemoglobin levels and oxygen tension, not enough blood can reach the tissues to deliver oxygen. Lastly, oxygen tension, which refers to the partial pressure of oxygen in the blood, significantly affects oxygen delivery. Higher oxygen tension in the alveoli leads to greater diffusion of oxygen into the bloodstream, ensuring that tissues receive sufficient oxygen. In contrast, while other choices include factors related to respiratory function and homeostasis, they do not centralize around the direct transport of oxygen as effectively as the correct choice does. Ventilation rate, blood pH, and heart rate contribute to overall respiratory and cardiovascular health, but they don't highlight the direct interplay between hemoglobin, blood flow, and the oxygen content of the blood.