Heart, organ that serves as a pump to circulate the blood. It may be as simple as a straight tube, as in spiders and annelid worms, or as complex as the four-chambered double pump that is the center of the circulatory system in humans, other mammals, and birds. In humans, the heart is approximately the size of a closed fist and is located between the lungs, in the middle compartment of the chest, called the mediastinum.

Understanding the Context

[4] Electrical impulses make your heart beat, moving blood through these chambers. Your brain and nervous system direct your heart’s function. What is the function of the heart? Your heart’s main function is to move blood throughout your body.

Key Insights

Blood brings oxygen and nutrients to your cells. Each heart gives one penalty point. There is also one special card, the Queen of spades, which gives 13 penalty points. When the game starts you select 3 cards to pass to one of your opponents. Typically you want to pass your three worst cards to get rid of them.

Final Thoughts

Learn about the anatomy of the heart and how its chambers, valves, and vessels work together to maintain effective blood circulation throughout the body to sustain life. This image shows the four chambers of the heart and the direction that blood flows through the heart. Oxygen-poor blood, shown in blue-purple, flows into the heart and is pumped out to the lungs. How the Heart Works - What the Heart Looks Like | NHLBI, NIH The heart is an organ, about the size of a fist. The heart is made of muscle and pumps blood through the body. Blood is carried through the body in blood vessels called arteries and veins.

The process of moving blood through the body is called circulation. Together, the heart and vessels make up the cardiovascular system.