Human Biology: The Circulatory System (grades 5-8)

The Human Circulatory System

The circulatory system includes the heart, the blood and the blood vessels. The circulatory system carries blood to the cells of the body. It also carries carbon dioxide and other wastes away from all parts of the body. The circulatory system also helps carry substances throughout the body that protect the body from disease. The heart is the pump that sends the blood coursing rapidly through the network of blood vessels.

Model of the Components of  Blood

Blood is made up of plasma, red blood cells, white blood cells, and platelets. 

Blood Typing

Blood typing is an interesting topic to learn about, but can get a little confusing sometimes, so we completed a little blood typing activity that clarified things.

The Heart and Blood Flow

Student (age 14) notebook page

The circulatory system delivers oxygen to all parts of the body. It takes two different routes. One route, the systemic circulation, carries oxygen-rich blood through arteries to all parts of the body. The same system returns the blood, now containing carbon dioxide, through veins to the heart for more oxygen. The other route, the pulmonary circulation, carries blood from the right side of the heart, travels only to the lungs to pick up oxygen, then returns the blood to the left side of the heart where it is sent on to the systemic circulation.

Student (age 10) notebook page

Veins, Arteries and Capillaries

We read about the difference between arteries and veins. Arteries are blood vessels that carry blood away from the heart and veins are blood vessels that carry blood back to the heart. We also learned that capillaries are tiny, thin-walled vessels that allow the exchange of gases and nutrients between the blood and cells. We then played the Circulation Game. As it says on the website in which I downloaded the free game, "this game is about some of the important jobs your blood does as it circulates throughout your body. In this game, you will help the blood pick up oxygen from the lungs, and food from the intestines and deliver them to the individual cells of the body. The blood will also pick up carbon dioxide and other wastes produced by the cells and get rid of them by taking them to the lungs or the kidneys.

The object of the game is to get oxygen and food to the cells, then get rid of the waste products produced by the cells. The cells will use the oxygen to burn the sugar and release energy. In this burning process, which is surprisingly similar to how a car engine works, carbon dioxide is produced as a waste product. The proteins are the ingredients your cells need in order to make repairs and build new cells. The cards marked "waste" represent the waste products made by the cells as they use up the proteins."