An Efficient System
By the time you are an adult, your heart
will beat more than 100,000 times a day!
The circulatory system has two important jobs.
The first job is to move blood. The second job is
to regulate the temperature of your body. The
circulatory system is made up of:
Your blood vessels
Your blood carries nutrients, oxygen, antibodies,
and hormones to the cells of your body. The heart
is the pump that moves the blood through the
blood vessels. As the blood travels along, it picks
up oxygen from the lungs and nutrients from the
Because humans are warm-blooded, their bodies
have a fairly steady body temperature. The
circulatory system helps to maintain this constant temperature by bringing
warmer blood from the center of the body to the surface to be cooled. The
circulatory system works with about four to five quarts of blood.
Directions: Use words or short phrases to answer the questions below.
1. Name the system that carries blood throughout the body.
2. List three things that make up the circulatory system. _____________,
3. Name two functions of the circulatory system. _____________________