WBCs and Platelets White blood cells WBCs are
WBCs and Platelets White blood cells (WBCs) are larger in size than RBCs and contain organelles. WBCs defend the body against invasion by pathogens, remove toxins, wastes and abnormal or damaged cells. WBCs do not always circulate in the blood stream like RBCs. They are sensitive to chemical signs of damage to surrounding tissues and use the blood stream to travel rapidly to these areas or from one organ to another. Once there, they can squeeze through adjacent epithelial cells in the capillary wall and move through loose or dense connective tissues. 50 -70% of the circulating white blood cells are neutrophils. These are usually the first WBCs to arrive at an injury and are phagocytic, attacking and digesting bacteria. After digesting bacteria the neutrophil dies, but when it breaks down it sends chemicals to attract other neutrophils.
Eosinophils usually represent 2 -4% of circulating WBCs. They attack objects that are coated with antibodies such as bacteria, protozoa and cellular debris. Their main mode of attack is the exocytosis of toxic compounds like nitric oxide and cytotoxic enzymes. Their numbers increase dramatically during parasitic infection or allergic reaction. Basophils represent less than 1% of circulating WBCs. They migrate to the site of injury and discharge the chemicals heparin and histamine. Histamine enhances local inflammation accompanying an injury. They also release chemicals to attract other WBCs. Monocytes represent 2 -8% of circulating WBCs. They are typically twice the size of an RBC. They are called free macrophages and are aggressive phagocytes. They will attempt to engulf items as large or larger than themselves and release chemicals to attract fibroblasts which produce scar tissue and walls off an injury.
Lymphocytes are slightly larger than RBCs and account for 20 -30% of the WBC population, but they continually migrate from the blood stream into peripheral tissues and back again, thus making them a much smaller percentage circulating WBCs. Lymphocytes are the only WBC that is not phagocytic, instead they release antibodies that attack foreign cells. Platelets initiate the clotting process and help close injured blood vessels. They are created in the bone marrow by enormous cells called megakaryocytes. They are continually replaced and only live for about 9 -12 days.
Diagram 1 st Left Side Activity Create a cluster map (example below) to represent the 5 different types of WBCs. List facts (min. 2) about each type in the first set of boxes. Then, draw and color a diagram of each type of Lymphocytes WBC in the second set of boxes using the Facts diagrams from Table 11 -3 in your book pg. 380. Diagram Monocytes Facts Basophil Facts Diagram WBCs Eosinophil Facts Diagram Neutrophil Facts Diagram
2 nd Left Side Activities Cut, color and glue the Blood and Blood Elements diagram given in class. 3 rd Left Side Activity Write a story (minimum 10 sentences) where you give each of the 5 types of WBC’s a name that starts with the first 2 letters of their actual name. Then have them interact in some way as those characters, while integrating qualities that will help you remember traits of those WBC’s. Example: Lydia (Lymphocytes) and Mona (Monocytes) were going to the Winter Formal. Eor (Eosinophil) and Newman (Neutrophil) had asked them to go, but Lydia did not know what to do. She kept going back and forth (what Lymphocytes do moving between the blood stream and peripheral tissues) because she was hoping to go with Baron (Basophil) who was such a rare individual (Basophils are the most rare WBC comprising only 1%) …………. . So on and so forth.
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