U3 S2

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U3 S2
2012-01-08 23:21:55

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  1. What is blood made of?
    An adult human body has about 5 liters of blood. Blood is made up of plasma, platelets, and red and white blood cells. Blood is a tissue because it is made of at least two different cell types.
  2. What is plasma?
    The fluid part of the blood is called plasma. Plasma is a mixture of water, minerals, nutrients, sugars, proteins, and other substances. The fluid also carries waste. Red blood cells, white blood cells, and platelets are fond in plasma.
  3. What are platelets?
    Platelets are tiny pieces of larger cells found in bone marrow. They last only 5-10 days. As soon as bleeding starts, platelets begin to clump together in the cut area. They form a plug that helps reduce blood loss. Platelets also release chemicals that react with proteins in plasma. The reaction causes tiny fibers to form. The fibers help create a blood clot.
  4. What are white blood cells?
    White blood cells keep you healthy by fighting pathogens such as bacteria and viruses. Some white blood cells squeeze out of blood vessels to search for pathogens. Once they find one, they destroy it. Other white blood cells form antibodies. Antibodies are chemicals that identify pathogens. White blood cells also keep you healthy by destroying body cells that have died or been damaged.
  5. What are red blood cells?
    Most blood cells are red blood cells. Red blood cells are disk-shaped cells that do not have a nucleus. The bring oxygen to every cell in your body. Cells need oxygen to carry out every function. Each red blood cell has hemoglobin. Hemoglobin is an oxygen-carrying protein; it clings to the oxygen molecules you inhale. Red blood cells can then transport oxygen to cells in every part of the body.
  6. How does blood move through the body?
    Blood is pumped from the right side of the heart to the lungs. From the lungs it returns to the left side of the heart. The blood is then pumped from the left side of the heart to the body. It flows to the tiny capillaries around the body before returning to the right side of the heart.
  7. How does blood circulate?
    Blood moves in two loops or circuits around the body. The flow of blood between the heart and the lungs is called the pulmonary circulation. The circulation of blood between the heart and the rest of the body is called systematic circulation.
  8. How does circulation help maintain body temperature?
    When the brain senses that body temperature is rising, it signals blood vessels in the skin to widen. As the vessels get wider, heat from the blood is transferred to the air around the skin. When the brain senses the body temperature is getting too low, it signals the blood vessels near the skin to get narrower. This allows the blood to stay close to internal organs to keep them warm.
  9. How can you get cardiovascular disease?
    Cardiovascular disease is the leading cause of death in the United States. Cardiovascular disease can by caused by smoking, poor diet, stress, physical inactivity, or in some causes, heredity.
  10. What is atherosclerosis?
    Atherosclerosis is a hardening of the artery walls caused by the buildup of cholesterol and other lipids. The buildup causes blood vessels to become narrower and less elastic. Blood cannot flow easily through a narrowed artery. When an artery supplying blood to the heart becomes blocked, oxygen cannot reach the heart muscle and the person may have a heart attack.