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What is the lymphatic system?
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A network of vessels that penetrate nearly every tissue of the body, and a collection of tissues and organs that produce immune cells
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What are the 3 functions of the lymphatic system?
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1. Fluid recovery
2. Immunity 3. Lipid absorption |
In the ___ special lymphatic vessels called ___ absorb dietary lipids that are not absorbed by the blood capillaries.
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Small intestine; lacteals
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What are the components of the lymphatic system?
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1. lymph- recovered fluid
2. lymphatic vessels- transport the lymph 3. lymphatic tissue- composed of aggregates of lymphocytes and monocytes 4. lymphatic organs- contain highly concentrated amounts of lymphocytes and monocytes which are set off from surrounding organs by connective tissue capsules |
Describe lymph
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-clear, colorless fluid similar to blood plasma but low in protein
-originates as tissue fluid taken up by the lymphatic vessels -composition varies from place to place -leaving the small intestine: milky appearance because of lipid content -leaving lymph nodes: contain large numbers of lymphocytes (main supply of lymphocytes to the bloodstream) -may contain macrophages, hormones, bacteria, viruses, cellular debris, or traveling cancer cells |
What is the source of the main supply of lymphocytes to the blood stream?
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Lymph leaving the lymph nodes
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The lymphatic system absorbs ___ and ___ and returns it back to the ___
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Plasma protein; tissue fluid; bloodstream
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How much fluid does the lymphatic system absorb per day?
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2-4 L
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Interference with lymphatic drainage can lead to ___
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Edema
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What are the smallest vessels in the lymphatic system and what are they similar to?
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Lymphatic capillaries; blood capillaries in the circulatory system
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Lymphatic capillaries are held to tissues by ____. These prevent what?
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Protein filaments; they prevent the sac from collapsing
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In what ways are lymphatic capillaries different from blood capillaries?
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-they are closed at one end, unlike the blood capillaries which are continuous.
-the endothelial cells are loosely overlapped and do not have a continuous basal lamina unlike blood capillaries in which they are tightly junctioned and do have a continuous basal lamina |
What is another name for the lymphatic capillaries?
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Terminal lymphatics
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What parts of the body are the lymphatic capillaries absent from?
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Central nervous system, cartilage, cornea, bone, and bone marrow
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What part of the lymphatic system allows larger cells and particles to enter along with the tissue fluid?
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The gaps between the capillaries (not a continuous basal lamina)
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