BBecause your muscles need more oxygen, so your heart pumps faster to deliver it
CBecause running shakes your heart
DBecause you are breathing harder
When you run, your muscles work hard and need more oxygen and energy. Your heart beats faster to pump blood more quickly to your muscles, delivering the extra oxygen they need. When you rest, your muscles need less, so your heart slows down.
Question 2 True / False
Your heart only works when you are awake.
TTrue
FFalse
Answer: False
Your heart beats every moment of your life — awake or asleep. If your heart stopped pumping, blood would stop flowing and your body parts would not get the oxygen and nutrients they need. Your heart never takes a break.
Question 3 Short Answer
What does blood carry to the different parts of your body?
Think about your answer, then reveal below.
Model answer: Blood carries oxygen from your lungs and nutrients from your food to all parts of your body. It also carries waste products away.
Blood is like a delivery truck. It picks up oxygen when it passes through your lungs and nutrients from your digestive system, then delivers them to your muscles, brain, and every other body part. On the return trip, it picks up waste that your body needs to get rid of.