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What system?
Organs, vessels and a fluid called lymph– similar to interstitial fluid (means clear water)
Lymphatic System
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What organs are involved in the lymphatic system?
- – red bone marrow
- – thymus
- – spleen
- – lymph nodes
- – lymph nodules
- • tonsils, adenoids & peyers patches
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What are the 3 main functions of the lymphatic system?
- •Draining excess interstitial fluid & plasma proteins from tissue spaces
- • Transporting dietary lipids & vitamins from GI tract to the blood
- • Facilitating immune responses
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What function of the lymphatic system is it?:
Recognize microbes or abnormal cells & responding by killing them directly or secreting antibodies that cause their destruction
Facilitating immune responses
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Capillaries that begin as closed-ended tubes found in spaces between cell combine to form ____________ ______
Lymphatic Vessels
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Resemble veins with thinwalls & more valves
Lymphatic vessels
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Fluid flows through lymph nodes towards large veins above the heart
– lymph emptied into bloodstream (subclavian veins)
Lymphatic circulation
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Found throughout thebody except in avascular tissue (cartilage, epidermis& cornea)
Lymphatic capillaries
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Lymphatic capillaries:
How is the structure designed to let tissue fluid in but not out?
- – anchoring filaments keep tubefrom collapsing under outside pressure
- – overlapping endothelial cells open when tissue pressure is high (one-way valve)
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Lymphatic capillaries in GI tract, are known as ______
lacteals
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What is collected by lymphatic capillaries & returned to the blood?
Fluid & proteins escaping from vascular capillaries
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What promotes flow of lymphatic fluid?
Respiratory movements & muscular contractions
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Vessels unite to form _________ & _________ ______
trunks; thoracic ducts
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What body areas empty into right lymphatic duct? The rest of body empties into thoracic duct (cysterna chyli)
Right side head, arm & chest
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Where is lymph dumped?
Directly into left and right subclavian veins
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Immune System and Lymphatic Tissue:
Form the main defense cells of the immune system
Lymphocytes
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What are the two main types of lymphocytes?
- B lymphocytes
- T lymphocytes
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What type of lymphocytes
-produced and mature in the bone marrow
-produce antibodies against specific antigens on foreign cells
B lymphocytes
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What type of lymphocytes are
-produced in the bone marrow but mature and proliferate in the Thymus gland
-attack foreign cells and program cell death
T lymphocytes
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Attack foreign cells and are short-lived
Effector cells
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Remain in system long time and provide rapid response to foreign cell (form the basis for vaccinations)
Memory cells
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Provide environment for stem cells to divide & mature into B and T lymphocytes
Primary lymphatic organs
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What gives rise to mature B cells?
Red bone marrow
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Site where pre-T cells from red marrow mature (newborn and young adult)
Thymus gland
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– site where most immune responses occur
• lymph nodes, spleen & lymphatic nodules
Secondary lymphatic organs & tissues
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What are the 5 types of lymphatic tissue?
- 1. Diffuse lymphatic tissue (diffuse lymph cells)
- 2. Aggregated lymphatic nodules (lymphatic nodules-clusters of lymphatic cells, nonencapsulated)
- 3. Lymph nodes (encapsulated clusters of lymph cells and blood vessels)
- 4. Spleen
- 5. Thymus Gland
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Concentrations of lymphatic tissue not surrounded by a capsule scattered throughout connective tissue of mucous membranes
Lymphatic Nodules
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Examples of Lymphatic Nodules
- • Peyer’s patches in the ileum of the small intestine
- • Appendix
- • Tonsils form ring at top of throat
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What are 3 parts of the tonsils?
- 1. Adenoids (pharyngeal tonsil)
- 2. Palatine tonsils (on each side wall)
- 3. Lingual tonsil in the back of the tongu
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Bean-shaped organs, up to 1 inch long, located along lymphatic vessels
Lymph Nodes
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Scattered throughout body but concentrated near mammary glands, axillae & groin
Lymph Nodes
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Is capsule, trabeculae & reticular fibers
Stroma
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Parenchyma is divided into 2 regions:
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Which region of the parenchyma:
• lymphatic nodules with germinal centers containing dendritic cells– antigen-presenting cells and macrophages
• B cells proliferate into antibody-secreting plasma cells
• T cells enter, proliferate and leave lymph node
Cortex
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Which region of the parenchyma:
• contains B cells & plasma cells in medullary cords
Medulla
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• Characteristic of malignant tumors
• Spread of disease from one organ to another– cancer cells travel via blood or lymphatic system– cells establish new tumors where they lodge
Metastasis
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How can secondary tumor site be predicted?
By direction of lymphatic flow from primary site
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Lymph nodes that are firm, enlarged and nontender
Cancerous lymph nodes
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Nodes that are not firm and are very tender
Infected lymph nodes
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Organ between stomach & diaphragm
Spleen
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Spleen:
Contains blood & lymphatic vessels
Hilus
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Spleen:
Consists of capsule, trabeculae, fibers & fibroblasts
Stroma
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Consists of white pulp and red pulp
Spleen
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What type of spleen pulp is lymphatic tissue (lymphocytes & macrophages), B cell proliferation and plasma cell formation
White pulp
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What type of spleen pulp is venous sinuses (filled with blood & macrophages)
Red pulp
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Spleen:
Carry out phagocytosis of bacteria and worn out RBCs and platelets
Macrophages
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Large organ in infants but atrophied in adult
2 lobed organ located in mediastinum
Thymus Gland
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Capsule & trabeculae divide it into lobules (connective tissue)
Thymus gland
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Each lobule has cortex &medulla
Thymus gland
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– tightly packed T lymphocytes (proliferation and maturation)
– Macrophages and epithelial cells-produce thymic hormon
Cortex of the Thymus Gland
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Mature T cells and patches of dead cells (thymic corpuscles)
Medulla of the Thymus Gland
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