The Circulatory System

The Circulatory System is responsible for transporting materials throughout the entire body. It transports nutrients, water, and oxygen to your billions of body cells .
What is the job of the Circulatory System?

Click here to see the circulatory system in action

The Circulatory System is responsible for transporting materials throughout the entire body. It transports nutrients, water, and oxygen to your billions of body cells and carries away wastes such as carbon dioxide that body cells produce. It is an amazing highway that travels through your entire body connecting all your body cells.
Parts of the Circulatory SystemThe circulatory System is divided into three major parts:
  1. The Heart - a muscle that pumps blood through your body.
  2. The Blood - carries oxygen, nutrients and waste throughout your body
  3. The Blood Vessels - the tubes that circulate blood throughout the body

Amazing Heart Facts
  • Your heart is about the same size as your fist.
  • An average adult body contains about five quarts of blood.
  • All the blood vessels in the body joined end to end would stretch 62,000 miles or two and a half times around the earth.
  • The heart circulates the body's blood supply about 1,000 times each day.
  • The heart pumps the equivalent of 5,000 to 6,000 quarts of blood each day.
Click here to label the parts of the heart!

aorta - the biggest and longest artery (a blood vessel carrying blood away from the heart) in the body. It carries oxygen-rich blood from the left ventricle of the heart to the body.
left atrium - the left upper chamber of the heart. It receives oxygen-rich blood from the lungs via the pulmonary vein.
left ventricle - the left lower chamber of the heart. It pumps the blood through the aortic valve into the aorta.
pulmonary artery - the blood vessel that carries oxygen-poor blood from the right ventricle of the heart to the lungs.
right atrium - the right upper chamber of the heart. It receives oxygen-poor blood from the body through the inferior vena cava and the superior vena cava.
right ventricle - the right lower chamber of the heart. It pumps the blood into the pulmonary artery.
superior vena cava - a large vein that carries oxygen-poor blood to the right atrium from the upper parts of the body.

 Amazing Blood Facts

What blood is made of...Blood is a mixture of fluid and solid matter.
  1. Plasma is the liquid part of our blood. It makes up about 50 – 60 % of it. Plasma consists mostly of water but many other substances are in it. It contains dissolved food, chemicals that control our growth and do other jobs, proteins, minerals and waste products.
  2. Red blood cells look like flat round discs. They contain haemoglobin, a protein that carries oxygen to the body and gives blood its red colour. Each drop of blood has about 300 million of these red cells.
  3. White blood cells, also called leukocytes, fight infections and harmful substances that invade the body. Most of these cells are round and colourless. They have different sizes and shapes. White blood cells are not as numerous as red ones. For every 700 red blood cells there is only one white blood cell.
  4. Platelets are tiny bodies that are much smaller than red blood cells. They stick to the edges of a cut and form blood clots to stop bleeding. The blood of a normal adult has about 2 trillion platelets.

Click here to see the heart in action!
Blood vessels are hollow tubes that are responsible for circulating blood throughout the body and maintaining our pulse and blood pressure. There are three basic types of blood vessels--veins, arteries and capillaries. Each has unique characteristics that help it to carry out its vital role in the human body.

Arteries are large blood vessels that carry oxygen-rich blood away from the heart to the rest of the human body.


Capillaries are thin and fragile blood vessels.  they are only one epithelial cell thick, forcing blood cells to pass through them single file. Capillaries are embedded throughout the body, connecting veins and arteries. Capillaries are responsible for two critical bodily functions. First, they facilitate the exchange of carbon dioxide and oxygen. After receiving oxygen-rich blood from arteries, capillaries release oxygen into the surrounding tissues and pass waste-rich blood containing carbon dioxide to veins, which carry it back toward the heart. Second, capillaries help the body release excess heat. When we exercise and our body temperature rises, or when our skin is exposed to hot substances (water) or temperatures, the capillaries release the heat into the tissue beneath the skin. This can sometimes cause a flushed or reddish appearance on the face or hands.

Veins are large blood vessels that carry waste-rich blood back to the heart.


Blood Types


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