Question

during a long-distance race, mateo’s muscles start to get tired because they need more oxygen and energy. his breathing rate increases to bring in more oxygen, and his heartbeat speeds up to deliver oxygen and nutrients through the blood. without this teamwork, his muscles would cramp and stop working. which two body systems are working together?

Explanation:

The scenario describes muscle activity needing oxygen/energy, breathing (respiratory system) bringing in oxygen, and heartbeat (circulatory system) delivering oxygen/nutrients. So the respiratory and circulatory systems work together.

Answer:

The respiratory system and the circulatory system.