Circulatory+13

The Circulatory System Names: Ethan, Lauren, Dean, and Hailey

The Circulatory System is the network of organs, vessels, and blood that travels throughout the body. This system is made up of the heart, the blood, and the blood vessels.

The heart is the most important single organ of the circulatory system. It is the size of an average person's fist and weighs between nine and eleven ounces. There are also four hollow spaces in the heart called chambers. Two of the them are on the right side of the heart and the other two are on the left side. Blood pumps in and out of the chambers through blood vessels. Towards the top of the heart there are two chambers called the atrium, and towards the bottom of the heart there are two chambers called the ventricle. The heart is mostly made of heart muscle known as cardiac muscle. Heart muscles on the left side of the heart are strongest. These muscles need its own supply of blood to work.

Another thing the circulatory system is made up, of is blood. Blood is a thick liquid that flows through a persons body, which is pumped by the heart and goes through the blood vessels. The blood transports things the body needs or has to get rid of. Blood is made up of a liquid called plasma, and three formed elements: white blood cells, red blood cells, and platelets. White blood cells fight diseases and try to get rid of bacteria or viruses. Red blood cells carry oxygen to all the cells in the body and carry some of the carbon dioxide from the cells and to the lungs. Platelets are a little bit smaller then red blood cells and one drop of blood contains thousands of platelets. If you got a cut, it damages the blood vessels and starts bleeding, but then stops after a while. This process is called clotting, and clotting is done by platelets. Platelets are made from giant cells in the bone marrow and only lives for ten days.

Finally, the circulatory system is made up of blood vessels. This system has three types of blood vessels: arteries, capillaries, and veins. Arteries carry blood away from the heart to almost all parts of the body. There are two arteries that the heart pumps blood into. The first one is called the pulmonary artery, and the second is called the aorta. Pulmonary arteries splits into two separate arteries for each lung. The aorta goes through the abdomen, and the arteries branch off from the aorta to the head, arms, and different organs. Capillaries take the blood to the body's cells before it flows into the veins for its return journey to the heart. As blood flows through the capillaries, oxygen and nutrients move through the cells. Veins are the thin blood vessels through which blood travels from the body and lungs, then back to the heart.

__Fun Facts__
 * the heart beats about three billion times in a persons life
 * blood circulates through the entire body in 20 seconds
 * one drop of blood has 5.5 million red blood cells and 12 thousand white blood cells
 * when you run around sometimes your face is a little bit pink or red because that is a sign that more blood than usual is flowing through the capillaries in the skin
 * William Harvey discovered blood circulation

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QUIZ TIME :) 1.Who was the first person that discovered blood circulation?  A. William Harvey  B. Albert Einstein  C. Barrack Obama  D. all of the above

2. How many days do platelets live for? A. five days B. nine days C. ten days D. twelve days

3. What is the most important single organ of the circulatory system? A. arteries B. heart C. blood D. blood vessel

4. What are the two chambers at the top of the heart called? A. platelets B. ventricle C. atrium D. heart

5. How many red blood cells are there in one drop of blood? A. 5.5 million B. 6.5 million C. 4.5 million D. 7.5 million

6. What is blood is made out of? A. blood, red blood cells, white blood cells, carbon dioxide B. capillaries, plasma, ventricle, white blood cells C. veins, arteries, oxygen, platelets D. plasma, red blood cells, white blood cells, platelets

7. How much does a heart weigh? A. 9 - 11 ounces B. 10 - 20 ounces C. 5 - 9 ounces D. 1 - 3 pounds

8. What do white blood cells do? A. carries oxygen B. fights diseases C. carries bacteria D. carries viruses

9. What do red blood cells do? A. carries oxygen B. does nothing C. spreads diseases D. all of the above

10. On which side of the heart are heart muscles stronger? A. right side B. left side C. in the middle D. on all the sides