Circulatory System

By: Isabelle Richter

Bishop-6th period

The Circulatory System (also known as the Cardiovascular System) is responsible for transporting materials throughout the human body. Nutrients, such as water and oxygen,  are transported by blood to billions of cells in our bodies and helps maintain homeostasis.  Homeostasis is the maintenance of a constant internal state in a changing environment. Wastes such as carbon dioxide that body cells produce are carried away. The Cardiovascular System is composed of the heart, blood vessels, including arteries, veins, capillaries and approximately five liters of blood that the blood vessels transport.

The Human Heart

The Human Heart is a muscular organ and  the most important part of  the Cardiovascular System. In the system, the heart pumps blood through the body. Without the heart, we wouldn't be able to function. First, the veins take deoxygenated blood  and deliver it to the lungs.  Then, the lungs oxygenate the blood before pumping  it into various arteries that provide oxygen and nutrients to body tissues.  

Four Chambers of The Heart

The heart consists of four different chambers; two atria and two ventricles.    


  • Right Atrium:  receives deoxygenated blood and delivers it to the right ventricle.
  • Right Ventricle:  pumps deoxygenated blood from the right atrium and pumps it into the lungs.
  • Left Atrium:  receives oxygenated blood from the lungs and pumps it to the left ventricle.
  • Left Ventricle:  pumps oxygenated blood from the left atrium into the body.

Blood Vessels

There are many blood vessels in our body and they can be different sizes.  The five types of blood vessels are arteries, arterioles, capillaries, venules and veins.  The three major types are arteries, veins, and capillaries.

  • Arteries:   carry blood from the heart to organs and muscles in the body, to give them the energy and oxygen.
  • Arterioles:  the smallest branch of an artery, terminating in the capillaries.
  • Capillaries:  between the ends of the arteries and the beginnings of the veins. They allow water, oxygen, carbon dioxide, and other nutrients and wastes to exchange between blood and surrounding tissues.
  • Venules:    small blood vessels that allow blood to return from the capillaries to the veins.
  • Veins: large blood vessels that convey blood from different parts of the body to the heart.

Blood/Blood Cells

Blood is a combination of plasma and cells that supply substances and nutrients (sugar, oxygen, and  hormones) to our cells.  Made up of two types of blood cells: white and red, blood carries waste away from those cells.

Plasma is the clear liquid in blood that remains after red blood cells, white blood cells,  and platelets are removed.  The largest component of human blood, plasma makes up about 55-percent of our blood and is mostly water, dissolved proteins, glucose, electrolytes, hormones, and carbon dioxide.

White Blood Cells flow through your blood stream to prevent and battle viruses, bacteria, and other diseases, while Red Blood Cells carry oxygen, remove carbon dioxide from your body, and transport it to the lungs for you to exhale.

Platelets are small blood cells that stop blood from bleeding by forming a clot or blockage.

Circulatory System Conclusion

Watch the video. Stop at 1.5 minutes.

Without the Circulatory System, your body wouldn't receive the oxygen and nutrients through blood needed for survival.  

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