CIRCULATORY+SYSTEM+3

=__**Circulatory System (Heart, Blood, and Vessels)** __ =

**Major Functions of the Circulatory System**

 * To generate blood pressure in our body
 * To route the blood to different organs
 * To ensure the blood flow goes one way
 * To regulate the blood supply
 * To deliver oxygen to all the cells
 * To remove carbon dioxide from all the cells

**Structure and Function of the Heart**
Heart cells are elongated, branching cells with one or two nuclei. Because of the cells **__shape, they are able to stretch and contract more efficiently__**. The myofilaments actin and myosin are the reason for why the cells can do this. Therefore, these cells can pump more blood, which is their main function. Also, the way heart cells are arranged makes them **__striated, so they can more easily stretch__**. The cells also have **__intercalated discs__** on them. These discs have many folds and attach to other discs in other cells. This helps **__all the cells stay together and not rip AND it coordinates all cells beating at the same time__**. Because of the heart muscle design, blood is able to be pumped very quickly, showing that structure fits function.

** Major Parts of the Heart **
The heart is mainly made up of four chambers: the left atrium, the right atrium, the left ventricle, and the right ventricle. The left atrium receives oxygenated blood from the lungs. The right atrium also recieves blood, but it is deoxygenated, and comes back from the cells. The left ventricle pumps oxygenated blood to the cells. The right ventricle pumps deoxygented blood to the lungs. The Aorta comes out from the left ventricle and delivers blood to other the cells. The pulmonary trunk comes out from the right ventricle and splits in two, which go to their respective lungs. The Inferior (lower) and Superior (higher) Vena Cavas join together and go into the right atrium, bringing in deoxygenated blood. The pulmonary veins come from the lungs and bring oxygenated blood to the left atrium. The coronary arteries are special in the sense that they only deliver blood to the heart's own wall. There are also four valves inside the heart. Two fo them allow blood to travel from the atriums to the ventricles, but not the other way around. The other two, similarly, allow blood to travel from the ventricles to the aorta or the pulmonary arteries, but not the other way around. []

First, deoxygenated blood goes into the right atrium. From there, the blood goes to the right ventricle through a valve. The right ventricle pumps the blood into the pulmonary artery which brings the blood to the lungs. Here, the blood is filled with oxygen and removed of carbon dioxide. From the lungs, the blood travels back into the heart by the pulmonary veins, which dumps the blood in the left atrium. From here, the blood passes into the left ventricle through a valve. The left ventricle pumps blood through the aorta to the cells. Here, the cells take the oxygen and replace it with carbon dioxide. From the cells, the blood eventually ends up in one of the vena cavas, and comes back to the right atrium of the heart. Then, the cycle starts over again.

IVC/SVC --> right atrium --> right AV valve (tricuspid valve) --> right ventricle --> pulmonary semilunar valve --> pulmonary arteries --> lungs --> pulmonary veins --> left atrium --> bicuspid valve --> left ventricle --> aortic semilunar valve --> aorta --> body

**__The molecule hemoglobin carries both oxygen and carbon dioxide in the blood__**. However, they attach to different areas of the hemoglobin molecule. Hemoglobin can be found inside of red blood cells.

**__Blood is made in the bone marrow__**, and there are 3 main components to blood. **__Red blood cells__** are disc shaped, and have wider edges than their centers. This help the cells bend so they can more easily pass through the bloodstream. Red blood cells lose their nuclei after they are created, so they cannot divide. These cells **__contain hemoglobin, which carries both oxygen and carbon dioxide__**. In contrast, **__white blood cells__** are spherical and don't contain hemoglobin. Unlike the red blood cells, they contain nuclei. Also, white blood cells are larger. Their main purpose is to **__protect the body from infection and remove waste from the blood__**. Lastly, **__platelets__** are parts of cells much smaller than red or white blood cells. They rush to the site of injuries so **__they can clot__**. This is to prevent the loss of blood from the body. []

**__Coronary artery disease__**, also known as CAD, is a condition in which **__plaque builds up inside the coronary arteries__**. These arteries supply your heart muscle with oxygen filled blood. **__Myocardial Infraction is what we call a heart attack__**. A heart attack occurs when **__oxygenated blood cannot get to a part of the heart, causing some of the cells there to die__**. This is usually caused by CAD. Smoking, high blood pressure, and a high cholesterol can also increase your risk of getting a heart attack. Age, gender, family history, obesity, physical inactivity, and stress are risk factors that may increase your chance of getting a heart attack.

** Four Incredible Facts **
[]
 * 1) Wine can help your heart. It contains many antioxidants that help make your heart stronger.
 * 2) In the event of a family death or a broken heart, you are more susceptible to heart attacks as your body triggers stress hormones to be released.
 * 3) Laughter can actually help your heart. A loud burst of laughter can allow the lining of blood cells on the wall to relax. This causes your blood flow to increase for up to 45 minutes.
 * 4) 10 million blood cells die every minute.

How the Circulatory System May Have Been Involved
If the pole had hit the heart or any large artery or vein, a large amount of blood would be released. This could explain why the driver had blood flowing from him. However, it is not likely that it hit the heart or any main vessels, as he would have died very quickly. **__The pole most likely hit lesser arteries or veins, that still released a lot of blood, but did not kill him.__**

Multiple Choice Questions
A: Deliver oxygen to cells B: To digest food in the body C: Remove carbon dioxide from cells D: To regulate blood pressure
 * 1. Which of the following is NOT one of the Circulatory System's functions?**

A: Striations B: Valves C: Interclated discs D: blood pressure
 * 2. What helps heart cells stay together and coordinates them to work together at the same time?**

A: Pulmonary Veins B: Pulmonary Arteries C: Aorta D: Vena Cava
 * 3. Which of the following sends deoxygenated blood to the heart?**

A: Myoglobin B: Hemocyanin C: Hemerythryn D: Hemoglobin
 * 4. What molecule carries oxygen and carbon dioxide in blood?**

A: To fight infection B: To clot blood C: To carry oxygen and carbon dioxide D: All of the above
 * 5. What is the function of platelets?**

A: The lungs B: The left ventricle C: Muscle cells D: The aorta
 * 6. Where in the body does blood lose carbon dioxide and gain oxygen?**

A: Not enough nutrients for the heart B: The coronary arteries exploding C: When oxygen is not able to get to the heart cells D: None of the above
 * 7. What is a heart attack caused by?**

A: Vodka B: Wine C: Beer D: Whiskey
 * 8. Which of the following beverages can help your heart?**

A: White blood cells B: Red blood cells C: Platelets D: They all have a nucleus
 * 9. Which of the parts of blood contain a nucleus?**

A: Right Atrium B: Left Atrium C: Right Ventricle D: Left Ventricle
 * 10. Which of the four main chambers of the heart pump oxygenated blood to the cells?**