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The Circulatory System 1. Your Blood: Fluid Transport i. Your blood is a tissue composed of fluid, cells, and fragments of cells. ii. The fluid portion of blood is called plasma. iii. Plasma is straw colored and makes up about 55 percent of the total volume of blood. b. Red blood cells: oxygen Carriers i. The round disk-shaped cells in blood are red blood cells. ii. Red blood cells carry oxygen to body cells. iii. They make up 44 percent of the total volume of your blood and are produced in the red bone marrow of your ribs, humerus, femur, sternum, and other long bones. iv. Red blood cells in humans have nuclei only during an early stage in each cell’s development. v. The nucleus is lost before the cell enters the blood stream. vi. Red blood cells remain active in the bloodstream for about 120 days, when they break down and are removed as waste. c. Oxygen in the blood i. Red blood cells are equipped with an iron-containing protein molecule called hemoglobin. ii. Oxygen becomes a loosely bound to the hemoglobin in blood cells that have entered the lung. iii. These oxygenated blood cells carry oxygen from the lungs to the body’s cells. d. Carbon dioxide in the blood i. Hemoglobin carries some carbon dioxide as well as oxygen. ii. You have already learned that once biological work has been done in a cell, wastes in the form of carbon dioxide diffuse into the blood and are carried in the blood stream to the lungs. iii. About 70 percent of this carbon dioxide combines with water in the blood plasma to form bicarbonate. iv. The remaining 30 percent travels back to the lungs dissolved in the plasma or attached to hemoglobin molecules that have already released their oxygen into the tissues e. White blood cells; Infection fighters i. White blood cells play a major role in protected our body from foreign substances and from microscopic organisms that cause disease. ii. They make up only one percent of the total volume of your blood.
Approximate Word count = 1366
Approximate Pages = 5.5
(250 words per page double spaced)
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