1.23. Heart http://www.ck12.org
1.23 Heart
- Describe the structure of the heart and how blood moves through the heart.
Where is your heart?
Place your hand on your heart. Did you put your hand on the left side of your chest? Most people do, but the heart
is actually located closer to the center of the chest.
The Heart
What does the heart look like? How does it pump blood? The heart is divided into four chambers (Figure1.41), or
spaces: the left and right atria, and the left and right ventricles. Anatrium(singular for atria) is one of the two small,
thin-walled chambers on the top of the heart where the blood first enters. Aventricleis one of the two muscular
V-shaped chambers that pump blood out of the heart. You can remember they are called ventricles because they are
shaped like a "V."
The atria receive the blood, and the ventricles pump the blood out of the heart. Each of the four chambers of the
heart has a specific job.
- The right atrium receives oxygen-poor blood from the body.
- The right ventricle pumps oxygen-poor blood toward the lungs, where it receives oxygen.
- The left atrium receives oxygen-rich blood from the lungs.
- The left ventricle pumps oxygen-rich blood out of the heart to the rest of the body.